Sencore SG-165 AM-FM Stereo Analyzer (operators and service)

Collection

Survival, Water, Medical Field Manuals

Case

Military Manuals

Download PDF ↗ Live URL (may be dead)

Document text

ENJ OY YOUR BOOKS 7

PLEASE VISIT OUR STORE FOR EVEN MORE GREAT
STUFF!

WWW.EVERYTHING4LESSSTORE.COM
COPYRIGHT NOTICE

ALL MATERIALS INCLUDING CD/ DVD AND PDF
FILES ARE COPYRIGHTED
WWW.EVERYTHING4LESSSTORE.COM VON
WALTHOUR PRODUCTIONS AND MAY NOT BE
REPRODUCED, COPIED OR RESOLD UNDER ANY
CIRCUMSTANCES. YOU MAY HOWEVER MAKE A
COPY FOR YOUR OWN PERSONAL BACKUP.
MATERIALS ARE FOR PERSONAL USE ONLY.

IF YOU PURCHASED THIS FROM ANYWHERE BUT
FROM US PLEASE NOTIFY US IMMEDIATELY SO
THAT WE MAY CHECK IF YOU PURCHASED FROM
AN AUTHORIZED RESELLER SO WE CAN LET YOU
KNOW IF YOU NEED TO RETURN FOR FULL REFUND
FROM AN UNAUTHORIZED SELLER.

THANKS AGAIN AND PLEASE TAKE THE TIME TO
VISIT OUR STORE.

ATTENTION! EVERYTHING ON SALE NOW!!

seman
cul

HOT SALE!

THIS PAGE COPYRIGHT VON WALTHOUR PRODUCTIONS
WWW.EVERYTHING4LESSSTORE.COM

SENCORE SAFETY REMINDERS

When testing electronic equipment, there is always a danger present. Unexpected high vol-
tages can be present at unusual locations in defective equipment. The technician should
become familiar with the device that he is working on and observe the following precautions.

When making test lead connections to high voltage points, remove the power. If this
cannot be done, be sure to avoid contact with other equipment or metal objects. Place
one hand in your pocket as a safety precaution and stand on an insulated floor to reduce
the possibility of shock.

Discharge filter capacitors before connecting test leads to them. Capacitors can store a
charge that could be dangerous to the technician.

Be sure your equipment is in good order. Broken or frayed test leads can be extremely
dangerous and can expose the technician to dangerous potentials.

Remove the test leads immediately after the test has been completed to reduce the possi-
bility of shock.

Do not work alone when working on hazardous circuits. Always have another person
close by in case of accident. Remember, even a minor shock can be the cause of a more
serious accident, such as falling against the equipment, or coming in contact with high
voltages.

When using the SG165 for signal injection, be sure to discharge the capacitor in the
39G43 probe to chassis before each connection. If this capacitor, charged to a large DC
voltage, is connected to the base of a transistor, possible damage to the transistor will
result.

TABLE OF CONTENTS

SENCORE SAFETY REMINDERS
SG165 FRONT PANEL
DESCRIPTION
INTRODUCTION
FEATURES
SPECIFICATIONS
CONTROLS
CONNECTIONS
OPERATION
SPEAKER LOAD AND POWER RANGE
STEREO MPX MODULATION
FM RF
10.7MHz IF
10.7MHz XTAL CONTROLLED
10.7MHz SWEEP & MARKERS
MPX SIGNAL
SCA 67KHz
AM RF
AM IF
400Hz AUDIO
EXTRA CRYSTAL
EXPLANATION OF STEREO
RECEIVER TESTS
CHECKING STEREO OPERATION
CHECKING THE SENSITIVITY OF AN
FM RECEIVER
CHECKING A RECEIVERS MAXIMUM
RMS POWER OUTPUT
CHECKING AN AMPLIFIERS SENSITIVITY
AND RMS POWER OUTPUT
SQUARE WAVE TESTING OF AUDIO
AMPLIFIERS
TESTING 4 CHANNEL OR QUAD SYSTEMS
RECEIVER ALIGNMENT
FM IF ALIGNMENT
FM RF ALIGNMENT
FM STEREO SEPARATION ADJUSTMENTS
AM IF ALIGNMENT
AM RF ALIGNMENT
RECEIVER TROUBLESHOOTING
RECEIVER BLOCK DIAGRAM
RECEIVER TROUBLE CHARTS
DB TABLE
SERVICING YOUR SG165 :
DISASSEMBLY INSTRUCTIONS
REMOVING THE MPX BOARD
SG165 CALIBRATION ADJUSTMENT
CIRCUIT DESCRIPTION - BLOCK DIAGRAM
CIRCUIT DESCRIPTION - CIRCUIT OPERATIONS
TROUBLE CHARTS
BOARD LAYOUTS
SERVICE AND WARRANTY

Inside front cover
Page 2
Page 3
Page 3
Page 3
Page 3
Page 5
Page 7
Page 8
Page 8
Page 9
Page 9
Page 10
Page 11
Page 11
Page 12
Page 13
Page 13
Page 14
Page 15
Page 16
Page 16
Page 19
Page 19

Page 20
Page 21
Page 22

Page 22
Page 25
Page 26
Page 26
Page 29
Page 30
Page 31
Page 32
Page 34
Page 34
Page 36
Page 38
Page 39
Page 39
Page 40
Page 40
Page 43
Page 45
Page 54
Page 57
Page 60

SEPARATION

SPEAKER LOAD POWER RANGE STEREO MPX MODULATION

LEFT PILOT RIGHT
8 46 SEPARATION. pe Si 400Hz I9KHz 400H2

SPEAKERS « 032 a.
SPEAKERS MUST
BE CONNECTED
TO USE THIS POS.
OFF ON

SENCORE $6165 AM-FM-STEREO ANALYZER

RF TUNING FM OUTPUT | AM OUTPUT
MODULATION MODULATION
31D if

MPK MX

ee Ne

RF RF :
— 10.7 MHz IF e i
. AOIMHE
yo : XTAL CONTROLLED i
EM _ og AM COW ONL
MHz | Hz 10.7MHz |, 400Hz
‘ SWEEP & MARKERS” SINE WAVE
aQOH?
MPX SIGNAL « © stiee aut

SCA 67KH2” | “EXTRA CRYSTAL

1
TO ROM MARKER AM/FM IF ROCKER MICRDVOLT OUTPUT
SCOPE ETECTOR HEIGHT LOWER HIGHER xO0D 5
ae — es
ie) =e) ee «x10

ALL SIGNAL OUTPUT

SENCORE INC. SIOUX FALLS. 6.0. 47107

Fig. 1 SG165 Front Panel

DESCRIPTION
INTRODUCTION

The AM/FM/FM MPX receiver represents the fastest
growing segment of the home entertainment elec-
tronics market. Many consumers consider the sound
system, whether component or console, their first
purchase after the essentials of food and shelter.

These consumers demand, and are willing to pay
relatively large sums for, quality reproduction of their
favorite music. When this equipment requires service
they expect the repaired unit to meet the same exact-
ing specifications it did when new. The technician
who attempts to test, troubleshoot and align a stereo
system, costing in some cases thousands of dollars,
without proper equipment has a difficult task ahead
of him. This need for a reasonably priced stereo
analyzer to adequately service and test stereo units
prompted Sencore to engineer the SG165 complete
AM/FM/Stereo Analyzer. The SG165, with its
accurate temperature compensated solid state cir-
cuitry, eliminates the guess work by providing known
accurate signals needed for full troubleshooting and
performance testing from antenna to speaker termi-
nals.

FEATURES

* Complete RF coverage of the AM and FM bands,
with band edge limits as recommended by re-
ceiver manufacturers.

* Troubleshooting signals for the FM IF, AM IF,
MPX, and audio circuits.

* Crystal controlled as well as swept 10.7MHz
with post injection crystal controlled 10.7MHz
marker, and 100KHz limit markers for FM IF
alignment.

* Tight shielding; no RF leakage to cause problems.

* 19KHz phase and frequency permanently locked
with exclusive Sencore (patent pending) circuit.

* Built in 4, 8, 16, and 32 ohm high wattage
dummy loads to eliminate the annoying howl in
the shop.

* Meters calibrated in db of separation and wattage
output up to 100 watts full scale. Compensated
to read accurate power output for any speaker
load resistor.

* Calibrated RF output for making the all impor-
tant IHF sensitivity check.

* Complete with all cables and adapters including
dummy auto antenna connector.

SPECIFICATIONS

NOTE: 1. All percentages are plus and minus
unless otherwise noted.
2. Temperature range for specified out-
puts 10 - 40 degrees C unless otherwise

noted.

EXTRA CRYSTAL

Holder type
Frequency Range
Circuit loading to
crystal

400Hz SINE WAVE

Frequency
Amplitude
Distortion

400Hz SQUARE WAVE

Frequency
Amplitude
Rise Time

262KHz and 455KHz IF

Frequency (in
center detent)
Rocker frequency
range

Amplitude
Modulation
percentage

AM RF

Frequency range
Dial calibration at
550 and 1600KHz

Amplitude
Modulation
percentage
FM RF

Frequency range

HC6U
3 - 12MHz

15pf

400Hz 20%
1V RMS 5%
5% maximum

400Hz 20%
2.8V p-p 30%
2 uSec. max.

262KHz or
455KHz 2%
25KHz above
and below center
.LV RMS 30%
25% to 45%
30% typical

525KHz to 1625KHz
4*5KHz at 20 degrees
C; £19KHz 10 to 40
degrees C

100mV 5% at 1000
KHz, 20% 525KHz
to 1625KHz

25% to 45%

30% typical

86 to 110MHz

Dial calibration at
88 and 108MHz

Dial tracking

Frequency change
with temperature
Amplitude (MICRO-
VOLT OUTPUT set

to 10 X 10) at 98MHz

Amplitude tracking

Modulation

10.7MHz IF

Frequency (center
detent)
Rocker range

Amplitude
Modulation
percentage

10.7MHz CRYSTAL

Frequency
Amplitude

10.7 SWEEP AND MARKER

Sweep width
Center Frequency

10.7MHz marker
Frequency
Amplitude

100KHz limit markers
Frequency
Amplitude

MPX SIGNAL

Frequency of 19KHz
pilot

Phase of 19KHz vs
88KHz

Amplitude (modula-
tion set to IHF)

£ 200KHz at 20 de-
grees C

+300KHz any mark,
20 degrees C
+200KHz, 10 - 40
degrees C

100uV 10%

20% 86 to
110MHz

STD: 30%
(22.5KHz) 20%
IHF: 100%
(75KHz) 20%

10.7MHz 1%

250KHz above and
below center

LV RMS 10%
STD: 30%
(22.5KHz) 20%
IHF: 100%
(75KHz) 20%

10.7MHz, .05%
.065V RMS 40%

500KHz typical
Rocker will center
sweep to 10.7MHz

10.7MHz .05%
1V p-p minimum

100KHz 3%
40% of 10.7MHz
marker typical

19KHz + 2Hz

permanently locked to
exceed FCC specifica-
tions with Sencore ex-
clusive (patent pending)
phase lock circuit.

2.5V p-p 25%

SCA 67KHz

Frequency 67KHz 3%
Amplitude 1V RMS 40%
Distortion 5% maximum
ATTENUATOR

Calibrated 20db
(X10) steps

Step attenuator

Variable attenuator
FM RF
All other outputs

0 to 18db typical
0 to 20db minimum

SG165 SPEAKER LOAD METER AND WATTS
RANGE SPECIFICATIONS

The meters on the SG165 measure the voltage across
the speaker load, as selected by the SPEAKER LOAD
switch. The sensitivity of this voltage measurement
is automatically compensated to maintain wattage
calibration for the 4, 8, 16 and 32 ohm positions of
the SPEAKER LOAD switch. In the SPEAKERS
position of the SPEAKER LOAD switch, the meter is
compensated to read the correct wattage at 8 ohms.
The accuracy of this voltage measurement is + 8%
for any position of the SPEAKER LOAD or METER
WATTS RANGE switches. The actual accuracy of
the wattage measurement is further affected by the
5% tolerance of the high wattage speaker load resis-
tors. The continuous power dissipation rating of the
speaker load resistors is 20 watts RMS to be derated
at higher power levels to 100 watts RMS per channel
maximum for a maximum of 5 minutes followed by
a minimum of 10 minutes cooling off time.

The SEPARATION scale on the meter uses 2.1
volts RMS as the reference and is calibrated in db
(voltage ratio) to a usable 40 db of separation.

CABLES SUPPLIED

1 - BNC to “F”’ connector cable to connect to
the SG165 ALL SIGNALS OUTPUT.

1 - Matching pad, (39G43) with 300 ohm
balanced (red and green leads) and 75 ohm
unbalanced (red and black leads) outputs.
(Mates with “F’’ connector on cable.)

1 - Combination detector probe (89G45) with
high impedance detector (blue lead) and isolat-
ion resistor (red lead).

1 - Auto radio dummy antenna (39G53) to
mate ‘‘F’’ connector to auto radio antenna
socket.

1 - Phono plug to alligator clip lead to connect
to the TO SCOPE jack. May also be used in

conjunction with the 39G48 to inject signals
into phono plug inputs of equipment under
test.

CABLES OPTIONAL

1 - BNC to phono plug (89G47) for connection
of TO SCOPE jack to scopes having BNC inputs.
May also be used to connect ALL SIGNALS
OUTPUT directly to phono plug inputs of
equipment under test.

GENERAL
Height 124%”? (32.2 cm)
Width 10” (25.4 cm)
Depth 9” (22.9 cm)
Weight 18 lbs (8.2 kg)
Power re- 105-180VAC 50/60Hz
quirements 7 watts

CONTROLS

ON-OFF - This slide switch controls the AC power
input to the SG165. The ON contition is indicated
by the red indicator lamp above the switch.

SPEAKER LOAD POWER RANGE
8 2 SEPARATION 10W 100W

SPEAKERS « <m* ped “~
SPEAKERS MUST
BE CONNECTED
TO USE THIS POS.

SENCORE Sl

Fig. 2° Speaker Load and Power Range Switches

SPEAKER LOAD - This rotary switch selects the
load connected across the LEFT AND RIGHT
CHANNEL OUTPUT meters. The SPEAKERS
position provides no load other than the meter
circuitry. The SPEAKERS MUST BE CONNECTED
to use this position.

POWER RANGE - This rotary switch selects the full
scale sensitivity of the LEFT and RIGHT CHANNEL
OUTPUT meters. The sensitivity for the SEPARA-
TION TEST position is 2.1 volts RMS full scale. In
the 10W and 100W positions, the SPEAKER LOAD

switch automatically adjusts the sensitivity of the
meters to maintain accurate wattage calibration for
the 4, 8, 16, and 32 ohm speaker loads. In the
SPEAKERS ONLY position the meters are compen-
sated to read the correct wattage for 8 ohm speakers.

STEREO MPX MODULATION

LEFT PILOT . RIGHT
400Hz 1SKHz 400Hz

10% ON

AM-FM-STEREO ANALYZER

Fig. 3 Stereo MPX Modulation

STEREO MPX MODULATION .- These three rocker
switches control the MPX signal produced by the
SG165. The LEFT 400Hz switch controls the left
channel signal, and the RIGHT 400Hz switch controls
the right channel signal. The 19KHz PILOT switch
selects the percentage of modulation of the 19KHz
pilot signal. The MPX signal as selected by the
STEREO MPX CONTROLS is used to FM modulate
the FM RF OUTPUT and the 10.7MHz IF signal. It
is also available as an output for direct injection into
the MPX decoder circuit of the receiver (MPX SIG-
NAL position of output control).

OUTPUT SELECTOR SWITCH

FM OUTPUT! AM OUTPUT
MODULATION MODULATION

sto IHF
MPX

10.7 MHz IF «

10.7 MHz
XTAL Pipes

& 7MHz 00
SWEEP & MARKERS” * SINE WAVE
400Hz
MPX SIGNAL « i cnuaeeanive
SCA 67KHz" * EXTRA CRYSTAL

Fig. 4 Output Selector

FM OUTPUT - The left hand side of the OUTPUT
SELECTOR SWITCH selects the various outputs
necessary to test, troubleshoot or align an FM or
FM MPX receiver.

MODULATION .- This slide switch selects the
percentage of modulation of the FM RF and
10.7MHz IF signals. The STD MPX position
provides 30% modulation (22.5KHz deviation)
as used by most FM stations, and the IHF MPX
position provides 100% modulation (75KHz
deviation) for the IHF sensitivity test. The
setting of the MODULATION switch will also
affect the level of the MPX SIGNAL output,
and should be in the IHF position to provide the
normal one volt RMS MPX Signal output.

RF - This output provides an FM RF signal
tunable from 86MHz to 110MHz, and frequency
modulated with the signal selected by the
STEREO MPX CONTROLS.

10.7MHz IF - This output provides a 10.7MHz
signal for injection into the IF amplifiers of the
FM receiver. It is tunable from approximately
10.45MHz to 10.95MHz by the AM/FM IF
ROCKER control and frequency modulated with
the signal selected by the STEREO MPX CON-
TROLS.

10.7MHz CRYSTAL CONTROLLED (CW
ONLY) - This output provides an accurate
crystal controlled signal for peak alignment of
standard FM IF amplifiers.

10.7MHz SWEEP AND MARKERS - This out-
put provides a sweep signal with a center fre-
quency tunable from approximately 10.45MHz
to 10.95MHz by the AM/FM IF ROCKER con-
trol, and a fixed sweep width of approximately
500KHz. A 10.7MHz crystal marker and 100
KHz limit markers are also generated and added
to the sweep response at the TO SCOPE output
jack.

MPX SIGNAL - This output provides the signal
selected by the STEREO MPX CONTROLS for
direct injection into the stereo decoder circuits
of the receiver. NOTE: The FM MODULA-
TION switch should be in the IHF position to
obtain the normal one volt RMS maximum sig-
nal output.

SCA 67KHz - This output provides an accurate
67KHz signal for aligning the SCA traps in the
FM receiver.

AM OUTPUT - The right hand side of the OUTPUT
SELECTOR SWITCH selects the signals necessary to
test, troubleshoot, or align an AM receiver; the 400

Hz sine and square wave signals, and the signal pro-
vided by the extra crystal position (crystal not
supplied).

MODULATION - This slide switch selects the
percentage of amplitude modulation (0 or 30%)
of the AM RF, 455KHz IF, and 262KHz IF
signals.

RF - This output provides an AM RF signal
tunable from 525KHz to 1625KHz and ampli-
tude modulated at 0 or 30% by a 400Hz sine
wave as selected by the MODULATION switch.

455KHz and 262KHz IF - These outputs pro-
vide signals for injection into the IF amplifiers
of standard AM receivers. They can be ampli-
tude modulated at 0 or 30% by a 400Hz sine
wave as selected by the MODULATION switch,
and are tunable over the range of *25KHz by
the AM/FM IF ROCKER control.

400Hz SINE WAVE and 400Hz SQUARE
WAVE - These outputs provide audio signals
for direct injection into the audio amplifier sec-
tions of any AM or FM receiver.

EXTRA CRYSTAL - This output selects the
signal generated by a separate internal crystal
oscillator (crystal not supplied) for injection
into any receiver requiring a nonstandard fre-
quency. The oscillator will accept crystals con-
tained in an HC6U holder in the frequency
range of 3 to 12MHz.

RF TUNING - This dial tunes the FM and AM RF
outputs. The FM output is tunable from 86 to 110

RF TUNING

COPE

Sy 2)
os % oO
C/ iss \
/ 1
FROM MARKER AM/FN
DETECTOR HEIGHT Lov

Fig. 5 RF Tuning control

MHz, and the AM from 525 to 1625KHz. A4tol
drive ratio is provided for increased tuning accuracy.

‘f eSB \
i uae
FROM MARKER AM/FM IF
E DETECTOR HEIGHT LOWER I}

SIGNAL OUTPUT

Fig. 6 Marker Height Control

MARKER HEIGHT - This control is operational only
in the 10.7MHz SWEEP & MKRS. output. Its
function is to vary the size (amplitude) of the 10.6,
10.7, and 10.8MHz markers that are added to the
response curve at the TO SCOPE jack.

3 \
he
1ARKER AM/FM IF ROCKER
HEIGHT LOWER P HIGHER X10

Xle

SENCORE INC.

JSS

Fig. 7 AM/FM IF ROCKER control

AM/FM IF ROCKER - This control provides a varia-
ble tuning for the 262KHz IF, 455KHz IF, 10.7MHz
IF, and 10.7MHz sweep to accomodate the newer
receivers with crystal filter IF’s. The range of con-
trol is typically 25KHz for the 262KHz and 455
KHz AM IF signals, and +250KHz for the 10.7MHz
FM IF and 10.7MHz sweep signals. The center de-
tent indicates the normal calibrated output frequency.

MICROVOLT OUTPUT - The output level of the
SG165 is controlled by two attenuators. The coarse
control is calibrated in 20db (X10) steps, and the
fine control provides an additional attenuation of
approximately 20db (X10).

MICROVOLT OUTPUT
x10 x100

Xle eX1000 4

g
30
did

ca ®
1 10
SENCORE INC. SIOUX FALLS, 5.0. 57107 105/120 VAC 50/60Hz

Fig. 8 Microvolt Output Controls

CONNECTIONS
a ys ls%
\
T0 FROM MARK
SCOPE DETECTOR HEIGI

—
ee oo

ALL SIGNAL QUTPUT

if _ -
Fig. 9 Front Panel Connections

ALL SIGNALS OUTPUT - This BNC connector is
the output terminal for all functions of the SG165.
The SG165 should only be used with the properly
terminated output cable to prevent standing waves
which could result in inaccurate outputs.

FROM DETECTOR - This phono jack is the input
for the response curve signal when the 10.7MHz
SWEEP & MKRS. function is in use. Use the 39G45
detector input cable to couple the response curve
from the receiver into this jack.

TO SCOPE - This phono jack is the output to the
oscilloscope vertical input for use with the 10.7MHz
SWEEP & MKRS. function. The signal leaving the
SG165 at the TO SCOPE jack is the same as that
applied to the FROM DETECTOR jack, with the
10.6, 10.7, and 10.8MHz markers added to it.

LEFT AND RIGHT CHANNEL OUTPUT METER
Leads - The two shielded alligator clip leads attached
inside the lead compartment near the line cord are
the input leads for the OUTPUT METERS. The
RED and black lead is for the RIGHT channel, and
the YELLOW and black lead for the LEFT channel.

OPERATION

SPEAKER LOAD AND POWER RANGE

GENERAL

The SPEAKER LOAD and POWER RANGE switches
control the load resistance and meter sensitivity for
the left and right channels simultaneously. The input
connections for the OUTPUT meters and SPEAKER
LOADS are the shielded cables attached to the SG165
inside the lead compartment near the line cord and
fuse. The RED and black cable connects to the
RIGHT CHANNEL OUTPUT meter and SPEAKER
LOAD, and the YELLOW and black cable connects
to the LEFT CHANNEL OUTPUT meter and SPEAK-
ER LOAD.

NOTE: The audio outputs of the amplifier or receiver
under test should be terminated with the correct load
at all times.

1. Connect the RED and black input cable to the
RIGHT channel amplifier output, and the YELLOW
and black input cable to the LEFT channel ampli-
fier output.

2. Use the SPEAKER LOAD switch to select the
correct load for the amplifier under test. Note that
in the SPEAKERS position, no load other than the
meter circuit is provided to the amplifier, and an
external load such as speakers must be connected to
the amplifier to prevent possible damage to the ampli-
fier output stage. Take care to limit the input power
to the SG165 speaker loads to an absolute maximum
of 100 watts RMS per channel.

SEPARATION TEST

Turn the POWER RANGE switch to the SEPARA-
TION TEST position, and read the 0 to -40db scale
on the LEFT and RIGHT CHANNEL OUTPUT
meters.

POWER OUTPUT TEST

Turn the POWER RANGE switch to the 10W or
100W position. Read the power output directly
in watts on the 0 to 10W scale for the 10W position
of the POWER RANGE switch, or multiply the met-
er reading by 10 for the 100W position.

LEFIMCHANNEL OUTPUT q RIGHNORANNEL OUTPUT

— LOAD POW!
a 2 SEPARATION

Suporte +32 hi r/
0 Pee rH POS

SENCORE $6165 AM-FM-STEREO ANALYZER

Fig. 10

¢ S/ io

LEF

Output Meters for Separation Test

WATTS

—
CHANNEL OUTPUT

SPE i LOAD

sae —_— Z
ie tomentes e
70 USE THIS POS

|
Fig. 11

Output Meters for Power Output Test

STEREO MPX MODULATION

PX MODULATION
PILOT RiGHT

19KHr 400h2
10%.
: : : : OFF ON
SENICORE $6165 AM-FM-STEREO ANALYZER

FM OUTPUT
MODULATION |

Oo Mis Te

Fig.12 Stereo MPX Modulation Conirols

The STEREO MPX CONTROLS are operational only
in the FM RF, 10.7MHz IF, and the MPX SIGNAL
positions of the output selector switch. In the FM
RF and 10.7MHz IF positions, the MPX signal selected
by the MPX CONTROLS is used to frequency modu-
late the output carriers. In the MPX SIGNAL
position, the signal selected by the controls is avail-
able as a direct output. NOTE: The FM Modulation
switch must be in the IHF MPX position to produce
the rated 1V RMS MPX signal. The following table
specifies the switch positions necessary to produce
the indicated signals with the STEREO MPX CON-
TROLS:

Monophonic 400Hz audio LEFT 400Hz-ON
RIGHT 400Hz-ON
PILOT 19KHz-Zero

Stereo, Left channel LEFT 400Hz-ON
only RIGHT 400Hz-OFF
PILOT 19KHz - 10%

Stereo, right channel LEFT 400Hz-OFF
only RIGHT 400Hz-ON
PILOT 19KHz - 10%

LEFT 400Hz-OFF
RIGHT 400Hz-OFF
PILOT 19KHz-10%

19KHz sine wave
(.1V RMS Max. in
MPX SIGNAL output)

FM RF

STEREO MPX MODULATION
LEFT PILOT RIGHT
4008 19KHe 400H2

RF TUNING FM OUTPUT
HOOULATION |

Bt ;
RPE a |
he

ALS SIGHAL GUTPET
: aes
6

MIDROVOLT GUTPUT
rit ane
eure »X 0 ,
j8 «ft
. A
. cf
. é

Fig. 13 Operational Controls for FM RF

The FM RF output is used to inject a signal with
composite stereo modulation into the antenna input
of any standard broadcast FM receiver. The tuning
range of the FM RF is from 86 to 110MHz, allowing
coverage of band edge limits as recommended by
some manufacturers of FM receivers. To use the
FM RF output, proceed as follows:

1. Setthe SG165 OUTPUT selector to FM RF, and
connect the BNC to “F” connector cable to the ALL
SIGNALS OUTPUT BNC connector.

2. Connect either the 39G43 75/300 ohm match-
ing pad, or the 39G53 auto radio dummy antenna to
the “‘F” connector end of the cable. Use the red and
green leads of the 39G43 for 300 ohm receiver inputs
or the red and black leads for 75 ohm inputs.

3. Adjust the STEREO MPX CONTROLS for the
desired modulation signal. (Refer to the STEREO
MPX CONTROLS-OPERATION section of this man-
ual).

4. Setthe FM MODULATION control to STD MPX
for 30% (+22.5KHz) modulation, or to IHF MPX for
100% (+ 75KHz) modulation.

5. Adjust the RF TUNING control for the desired
output frequency. The dial indicator for the FM RF

frequency is the horizontal line on the small rectan-
gle labeled FM MHz located to the left of the RF
TUNING control. The RF TUNING dial is calibrated
at intervals of 1MHz, with the small unnumbered
marks corresponding to odd numbers. For example
the small mark between 98 and 100MHz corresponds
to an output frequency of 99MHz.

6. Adjust the MICROVOLT OUTPUT controls for
the desired output signal level. To determine the
signal output level (measured in microvolts at the
ALL SIGNALS OUTPUT) for the FM RF output
multiply the setting of the coarse MICROVOLT OUT-
PUT control by the corrected vernier control output
from the table.

CONTROL SETTING CORRECTED OUTPUT

1
©

Brow ROO ~I0 6
PA Fa BD GO HB OTS CO
NW ROROOHAH

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

10.7MHz IF

The 10.7MHz IF output is used to inject a signal
with composite stereo modulation into the IF amp-
lifiers of standard broadcast FM receivers for test and
troubleshooting purposes. The frequency of the 10.7
MHz output is variable from approximately 10.45 to
10.95MHz with the AM/FM IF ROCKER control to
allow injection of this signal into the IF amplifiers of
receivers employing fix tuned or crystal filter IF
amplifiers. The 10.7MHz IF signal is intended pri-
marily as a troubleshooting signal. The stage gain of
each IF stage can be determined by injecting 10.7
MHz IF signal into the input of each IF stage and
noting the signal level required by each stage to pro-
duce a given output. To use the 10.7MHz IF output,
proceed as follows:

1. Set the SG165 OUTPUT selector to 10.7MHz
IF, and connect the BNC to ‘‘F’”’ connector cable to
the ALL SIGNALS OUTPUT BNC connector.

2. Connect the 39G43 75/300 ohm matching pad
to the “‘F’’ connector end of the cable. Use the red
and black leads of the 39G43 to inject the 10.7MHz
IF signal.

"MPX MODULATION
PILOT RIGHT
19KHz 400Hr
0x sos, OM
Sx
ON

SENCORE $6165 AM-FM-STEREO ANALYZER
ers

¥ |

ABASEM TE BECKER MICROVOLT OUTPUT
{aera Busnes x10 100

ad. SIGHAL GuTPET: 5
i :
Zé |

Operational Controls for 10.7MHz IF

Fig. 14

3. Adjust the STEREO MPX CONTROLS for the
desired modulation signal. (Refer to the STEREO
MPX CONTROLS - OPERATION section of this
manual.)

4, Setthe FMMODULATION control to STD MPX

for 30% (1 22.5KHz) modulation, or to IHF MPX for
100% (+ 75KHz) modulation.

5. Adjust the AM/FM IF ROCKER control if the
receiver being tested uses crystal filter or fix tuned
IF’s. The normal adjustment procedure for the
ROCKER control is to inject the 10.7MHz IF signal
into the receiver, and adjust the control for maximum
undistorted signal at the output of the receiver.

6. Adjust the MICROVOLT OUTPUT controls
for the desired output signal level. To determine
the signal output level (measured in microvolts at the
ALL SIGNALS OUTPUT) for the 10.7MHz IF out-
put, multiply the setting of the coarse MICROVOLT
OUTPUT control by 10, and the result by the correc-
ed vernier control output from the table.

CONTROL SETTING CORRECTED OUTPUT
10 10
9 8.3
8 — 6.9

Pw hoe
Coes tae
BH ~Tho WIEN ON OO

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

10.7MHz XTAL CONTROLLED

FM OUTPUT

7 SIGNAL Bure
o
[ Cie.

Fig. 15 Operational Controls for 10.7MHz Crystal

The 10.7MHz CRYSTAL CONTROLLED output pro-
vides an accurate 10.7MHz crystal controlled un -
modulated signal for aligning the IF amplifiers of
standard FM broadcase receivers. It can be used to
accurately peak align the receiver IF amplifiers to
10.7MHz, or as a preliminary step to sweep align-
ment. The 10.7MHz crystal controlled signal also
provides the most accurate method for zeroing the
FM detector to exactly 10.7MHz. To use the 10.7
MHz CRYSTAL CONTROLLED signal, proceed as
follows:

1. Set the SG165 OUTPUT selector to 10.7MHz
CRYSTAL CONTROLLED, and connect the BNC
to “F” connector cable to the ALL SIGNALS OUT-
PUT BNC connector.

2. Connect the 39G43 75/300 ohm matching pad
to the “‘F”’ connector end of the cable. Use the red
and black leads of the 89G43 pad to inject the 10.7
MHz CRYSTAL CONTROLLED signal.

3. Adjust the MICROVOLT OUTPUT controls for
the desired output signal level. To determine appro-
ximately the signal output level (measured in micro-
volts at the ALL SIGNALS OUTPUT) for the 10.7
MHz CRYSTAL CONTROLLED output, multiply
the setting of the coarse MICROVOLT OUTPUT con-
trol by 6.5, and the result by the corrected vernier
control output from the table.

CONTROL SETTING CORRECTED OUTPUT

fuad
©
a
wo CO

FAD co OO ~100
er Oo: fa ie ce ee
HS 1 bo WI O11 00 ©

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

10.7MHz SWEEP AND MARKERS

The 10.7MHz SWEEP and MARKERS function pro-
vides a 10.7MHz sweep signal, with post injection
markers at 10.6, 10.7, and 10.8MHz, for accurate
sweep alignment of the IF amplifiers and detector of
any FM Stereo receiver. Even the newest receivers
using fix tuned or crystal filter IF’s are covered with
the ROCKER that allows you to vary the sweep cen-
ter frequency over the normal range of these fix
tuned circuits. The large amplitude markers are
variable with the marker height control, and because
of the post injection system used will not effect the
size or shape of the IF response curve. To use the
10.7MHz SWEEP and MARKERS function, proceed
as follows:

1. Set the SG165 OUTPUT selector to 10.7MHz
SWEEP & MARKERS. Use the phono plug to alli-
gator clip lead (supplied) to connect the TO SCOPE
jack on the SG165 to the vertical input of an oscill-
oscope, and set the oscilloscope vertical input con-
trols for .5V p-p per inch (.2V p-p per cm.) Turn
the oscilloscope horizontal frequency control to the
internal 60Hz position, and adjust the oscilloscope
phase control for a pattern with no indication of
fold over.

SENCORE $6165 AM-FM-STEREO ANALYZER _

FM OUTPUT

1O7MHr
SWEEP & MARKERS

ti HOM * MARKER AM/TM IF ROCKER MICROVOLT OU TRL
Pt ETELTOR HEGHET wit aoe x0 nd
$8 Wok
e oy ~ Kle KIO 4 ‘
te +f
ALL SIGNAL QUTPIT
* eG
ro a
0
er - — Wc 4
r

Fig. 16 Operational Controls for 10.7MHz Sweep
and Markers

2. Plug the 39G45 detector probe to the FROM
DETECTOR jack on the SG165. Connect the red
lead of the 39G45 to the receiver testpoint if the
testpoint is after the detector (audio), and the blue
lead if the test point is before the detector (10.7
MHz).

3. Connect the BNC to ‘‘F”’ connector cable to the
ALL SIGNALS OUTPUT BNC connector, and the
39G43 75/300 ohm matching pad to the “F” con-
nector end of the cable. Use the red and black
leads of the 39G43 pad to inject the 10.7MHz sweep

signal.

4, Adjust the AM/FM IF ROCKER control to
center the response on the oscilloscope sweep.

5. Adjust the MICROVOLT OUTPUT controls for
just enough signal to obtain a clean response curve.
(It is normal for some noise to appear on the base
line near the edges of the sweep.)

6. Adjust the MARKER HEIGHT control for mar-
kers of the desired amplitude. (It is normal for the
amplitude of the 10.6 and 10.8MHz markers to be
approximately 40% of the 10.7MHz marker).

10.6

Fig. 17 IF Response and Detector Response

MPX SIGNAL

STEREO MPX MODULATION
LEFT PILOT RIGHT
400Hz 19KHz 400H2
_.. 102

FM OUTPUT

T OUTPUT
x ¢ 5
we *
i ok. Xte x00 4, .
: “Ss — Je <i
Ail SIGNAL OUTPUT ae £ a
= J . Z . 94
©) ae _—

Fig. 18 Operational Controls for MPX signal

The MPX SIGNAL output provides a composite
stereo signal for direct injection into the stereo multi-
plex circuits of FM stereo receivers and stereo adapt-
ors. The MPX SIGNAL can either be used as an
alignment signal, or as a troubleshooting signal to
isolate a receiver poor stereo separation problem to
the multiplex or RF/IF circuits. To use the MPX
SIGNAL, proceed as follows:

1. Set the SG165 OUTPUT selector to MPX SIG-
NAL, and connect the BNC to “F’’ connector cable
to the ALL SIGNALS OUTPUT BNC connector.

2. Connect the 39G43 75/300 ohm matching pad
to the “‘F” connector end of the cable, and use the
red and black leads of the pad to inject the MPX
SIGNAL’

3. Adjust the STEREO MPX CONTROLS for the
desired output signal. (Refer to the STEREO MPX
CONTROLS - OPERATION section of this manual.)

4. Set the FM MODULATION switch to IHF MPX.

5. Adjust the MICROVOLT OUTPUT controls for
the desired output signal level. To determine the
signal output level (measured in milivolts at the ALL
SIGNALS OUTPUT) for the MPX SIGNAL, multiply
the setting of the coarse MICROVOLT OUTPUT con-
trol by .1, and the result by the corrected vernier
control output from the table. (The level of the
PILOT 19KHz with the switch set to 10% will be
approximatly one tenth of the composite output).

CONTROL SETTING CORRECTED OUTPUT

10 10
9 8.3
8 6.9
7 4.8
6 3.5
5 2.5
4 It
3 1.2
2 87
1 04

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

SCA 67KHz

The SCA 67KHz output provides an accurate 67KHz
output for alignment of SCA or 67KHz traps in FM
stereo receivers. The SCA 67KHz signal would nor-
mally be injected at the detector composite audio
output, and the receiver’s trap adjusted for minimum
67KHz at the output of the stereo decoder. To use
the SCA 67KHz output, proceed as follows:

1. Setthe SG165 OUTPUT selector to SCA 67KHz
and connect the BNC to ‘“‘F” connector cable to the
ALL SIGNALS OUTPUT BNC connector.

2. Connect the 39G43 75/300 ohm matching pad
to the ‘“‘F”’ connector end of the cable, and use the
red and black leads to inject the 67KHz signal.

38. Adjust the MICROVOLT OUTPUT controls as
necessary to obtain a minimum usable signal.

SENICORRE $6165 AM-FM-STEREO ANALYZER

FM OUTPUT

MinRAVOLT OU TPL
Le xift Xe} & §
2 * a
- Xt em o X06 $, a
: te #6

ALL SIGNAL GUTPU?

ae ’ : 3° ee

. °

Fig. 19 Operational Control for 67KHz

AM RF

The AM RF output is used to inject an amplitude
signal into the antenna input of any standard AM
broadcast receiver. The tuning range of the AM RF
is from 525 to 1625KHz, allowing coverage of the
band edge limits as recommended by some manufac-
turers of AM receivers. To use the AM RF output,
proceed as follows:

1. Set the SG165 OUTPUT selector to AM RF,
and connect the BNC to “F” connector cable to the
ALL SIGNALS OUTPUT BNC connector.

2. Connect either the 39G43 75/300 ohm matching
pad, or the 39G53 auto radio dummy antenna to the
“F’? connector end of the cable. Use the red and
black leads of the 39G43 for receivers with external
AM antenna connections, or allow the signal from the
leads of the 39G43 to radiate into the receivers rod
antenna for receivers without external antenna con-
nections.

3. Select either 30% modulated, or unmodulated
carrier output with the AM MODULATION switch.

AM OUTPUT
MODE ATIIN

Fig. 20 Operational Control for AM RF

4. Adjust the RF TUNING control for the desired
output frequency. The dial indicator for the AM RF
frequency is the horizontal line on the small rectan-
gle located to the right of the RF TUNING control.
The AM side of the RF TUNING dial is calibrated at
intervals of 50KHz from 550 to 1000KHz, and at
intervals of 100KHz from 1000 to 1600KHz.

5. Adjust the MICROVOLT OUTPUT controls for
the desired output signal level. To determine the
signal output level (measured in microvolts at the
ALL SIGNALS OUTPUT) multiply the setting of the
coarse MICROVOLT OUTPUT control by 10, and
the result by the corrected vernier control output
from the table.

CONTROL SETTING CORRECTED OUTPUT

a
cm)
(om)

Rn cob Om ~10
qa & See are
i ~1 bo WO Ot 0 © &

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

AM IF

Fig. 21 Operational Control for AM IF

The 455KHz and 262KHz outputs are used to inject
an amplitude modulated signal for troubleshooting or
alignment into the IF amplifiers of standard AM
broadcast receivers. The 262KHz output is used
primarily for auto radios, and the 455KHz for most
portable, and in home radios. The frequency of the
455KHz and 262KHz outputs is variable over a plus
and minus 25KHz range to allow injection of these
signals into the IF amplifiers of receivers employing
fix tuned or crystal filter IF amplifiers. To use the
455KHz or 262KHz IF output, proceed as follows:

1. Set the SG165 OUTPUT selector to either 455
KHz IF or 262KHz IF, and connect the BNC to “F”’
connector cable to the ALL SIGNALS OUTPUT BNC
connector.

2. Connect the 39G43 75/300 ohm matching pad
to the “‘F’’ connector end of the cable. Use the red
and black leads of the 39G43 to inject the AM IF
signal.

3. Use the AM MODULATION switch to select
either a 30% modulated or unmodulated carrier out-
put.

4, Adjust the AM/FM IF ROCKER control if the
receiver being tested uses crystal filter or fix tuned
IF amplifiers. The normal adjustment procedure for
the ROCKER control is to inject the AM IF signal
into the receiver, and adjust the control for maximum
undistorted signal at the output of the receiver.

5. Adjust the MICROVOLT OUTPUT controls for
the desired output signal level. Remember to keep
the level as low as possible during alignment proce-
dures to prevent overload to the IF amplifiers. To
determine the signal level (measured in microvolts
at the ALL SIGNALS OUTPUT) for the AM IF
outputs, multiply the setting of the coarse MICRO-
VOLT OUTPUT control by 10, and the result by the
corrected output of the vernier control from the
table.

CONTROL SETTING CORRECTED OUTPUT

ea ee
bo Wao ot & to

ENwWROAWOOH
on
SG

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

400Hz AUDIO

The 400Hz audio outputs are used to inject a signal
into any audio amplifier for test or troubleshooting
purposes. The 400Hz SINE WAVE output is most
useful for distortion and maximum power output
tests, while the 400Hz SQUARE WAVE is most use-
ful for evaluating the frequency response of the audio
amplifier. To use the 400Hz audio outputs, proceed
as follows:

1. Set the SG165 OUTPUT selector to either 400
Hz SINE WAVE, or 400Hz SQUARE WAVE, and
connect the BNC to ‘“‘F’’ connector cable to the
ALL SIGNALS OUTPUT BNC connector.

2. Connect the 39G43 75/300 ohm matching pad
to the “‘F’’ connector end of the cable. Use the red
and black leads of the 39G48 for injecting the 400Hz
audio signals directly into the circuitry of the ampli-

: a 2 OFF ON : io :
SENCORE $6165 AM-FM-STEREO ANALYZER _

AM OUTPUT

Fig. 22. Operational Control for Audio Signals

fier, or connect the 39G48 to the phono plug to alli-
gator clip cable (black to black lead and red lead to
red lead) for injecting signals into phono plug inputs.

3. Adjust the MICROVOLT OUTPUT controls for
the desired signal level. To determine the signal out-
put level (measured in millivolts RMS at the ALL
SIGNALS OUTPUT) for the 400Hz SINE WAVE,
multiply the setting of the coarse MICROVOLT
OUTPUT control by .1, and the result by the correct-
ed vernier control output from the table below. To
determine the signal output level (measured in milli-
volts peak to peak at the ALL SIGNALS OUTPUT)
for the 400Hz SQUARE WAVE, multiply the setting
of the coarse MICROVOLT OUTPUT control by .28
and the result by the corrected vernier control output
from the table.

NOTE: When using the SG165 to drive low impe-
dances, such as loudspeakers, the output will be
somewhat lower than that indicated. The level at the
ALL SIGNALS OUTPUT, loaded with 8 ohms is
approximately 1V p-p, and the signal at the output
of the red and black leads of the 39G43 loaded with
8 ohms is approximately .2V p-p.

CONTROL SETTING CORRECTED OUTPUT
10 10
9 8.3
8 6.9
7 4.8
6 3.5
9) 2.5
4 1.7
3 1.2
2 87
1 54

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

EXTRA CRYSTAL

SENCORE $6165 AM-FM-STEREO ANALYZER

EXTRA CRYSTAL
MICROVOLT OUTPUT
x10 = -xIh0 ‘ i
* . * -*
nee ro Xe #1006 4, Fs
st Se ee
ae ae a ie of
' - = cs
ALL SIGHAL GaTeur a 4 es &
SB a 4 2 2
é : se . q
Co :
we WERKE IW cFMIN LR mK Se
— ‘hae ai 4

po “

Fig. 23 Operational Control for Extra Crystal

The EXTRA CRYSTAL output provides a signal
whose frequency is controlled by the crystal (not
supplied) inserted into the extra crystal socket. The
EXTRA CRYSTAL signal (with proper crystal in-
stalled) can be used to test, troubleshoot, and align
any circuit requiring a frequency in the range of 3 to
12MHz. To use the extra crystal output, proceed as
follows:

1. Install the desired crystal into the extra crystal

socket. (Refer to INSTALLING EXTRA CRYSTAL
in service manual) .

Fig. 24

2. Set the SG165 OUTPUT selector to EXTRA
CRYSTAL, connect the BNC to “F” connector cable
to the ALL SIGNALS OUTPUT, and connect the
39G43 75/300 ohm matching pad to the “F” con-
nector end of the cable.

3. Adjust the MICROVOLT OUTPUT controls for
the desired signal output. Note the output level, and
frequency accuracy of the extra crystal signal will
depend entirely on the crystal used.

EXPLANATION OF STEREO

Several receiver systems are currently in use, but une
most common is the 4 diode full wave decoder. There
are slight differences in the operation of this circuit
whether it is decoding the stereo signal from the
broadcast station or the simulated stereo signal from
the SG165 although, the critical phase relationship
between the 19KHz pilot, and the 38KHz subcarrier
signal is the same.

COMPOSITE SIGNAL
LEFT @ TO MODULATOR
400Hz ABAB
400Hz fa) ® ®
SIF i] A\ To
Roane ; CR212 Ms

How the SG165 Generates a Stereo Signal

WITH THE $6165

SG165 OPERATION

The SG165 generates its stereo signal using a simple
time switching . multiplexer.
SG165 transmits the left channel signal during one
alternation of its 383KHz switching signal, and the right
signal during the next alteration. Fig. 24 shows the

In other words, the

circuitry used in the SG165 to produce the stereo
signal. At time A, when the switching signal is
positive at point 1 and negative at point 2, diodes
CR207 - 210 are in the ON state, allowing the left

channel signal to pass to the modulator. The positive
switching signal is also present as point 3, causing
diodes CR211-214 to be in the off state, blocking the
right channel signal from the modulator. During
time B point 1 is negative and point 2 is positive,
turning diodes CR207 - 210 off, and blocking the
left channel signal from the modulator. Point 3
would be negative turning on diodes CR211 to 214,
and allowing the right channel signal to pass through
to the modulator. The SG165 also generates a 19
KHz pilot signal that is held in exact phase with the
38KHz switching signal.

RECEIVER OPERATION

38KHz
OUTPUT
XFMR

COMPOSITE
STEREO At ne
SIGNAL — CY®OH®

Fig. 25 How the Receiver Processes the SG165

Signal

In the receiver, the 19KHz signal is amplified and
doubled, to produce a 88MHz signal that is exactly in
phase with the 38KHz used in the generator. The
composite stereo signal is decoded using the 38KHz
to provide the original left and right signals. Fig. 25
shows the operation of the common 4 diode circuit
with the signal from the SG165. The composite signal
(the same as went to the modulator in the SG165) is
injected into the center tap of the 38KHz transformer
secondary, therefore this signal would be present at
both points 1 and 2 with equal amplitude and phase.
The phase of the 38KHz signal is such that at time A
point 1 would be positive with respect to point 2,
and diodes D1 and D3 on. With both D1 and D3 on,
the left channel signal present at points 1 and 2
during time A would be coupled to the top of the
left channel load resistor R1. During time B point 2
would be positive with respect to point 1, turning on
diodes D2 and D4. With D2 and D4 on, the right
channel signal present at points 1 and 2 would be
coupled to the right channel load resistor R2.

WITH THE STATION SIGNAL
TRANSMITTER OPERATION

The system used by the FM station to generate the
stereo signal is more complicated than that used by

LEFT
SIGNAL
RIGHT
SIGNAL
LOWER

LEFT
CHANNEL
SIGNAL

UPPER
e SIDEBAND SIDEBAND
,
‘
'
a ' =
L+R ‘ '
'
:
1 2 jz
:
:
4 F
No. 1

BALANCED
MODULATOR

CHANNEL
SIGNAL

OSCILLATOR

RIGHT
SIGNAL

Fig. 26 Block Diagram of FM Stereo Transmitter

the SG165. The block diagram in Fig. 26 shows
how the Stereo signal is generated at the FM trans-
mitter. The left and right channel signals are added
together in adder 1 to produce the sum of the two, or
the L + R signal. (Fig. 26) The L + R signal is then
applied to the mixer. Next the right channel signal
is inverted and added to the left channel signal in
adder 2. The result of adder 2 is the L- R signal.
(Fig. 26) The L - R signal is AM modulated on a
388KHz carrier using a balanced modulator. The out-
put of the balanced modulator (upper and lower
sidebands) is applied to the mixer. A 19KHz sine
wave is generated from the 38KHz used in the bala-
nced modulator and also applied to the mixer. The
output of the mixer called the composit signal is then
used to modulate the RF carrier.

RECEIVER OPERATION

The operation of the receivers 19KHz and 38KHz
circuits is exactly the same on the station signal as it
was with the SG165. The composite signal is injected
into the center tap of the 38KHz transformer where
the 38KHz carrier is reinstated to the sidebands con-
taining the L - R information.

The result of the carrier reinsertion is the modulation
envelope shown. in Fig. 27. Note that the positive

iy
NX \ yy \ \

Fig. 27 38KHz Modulation Envelope

side of the modulation envelope looks exactly like
the L - R signal generated at the transmitter, while
the negative side of the modulation envelope is a
mirror image of the L - R signal, or a -(L - R) signal.

During time A (Fig. 28) when point 1 is positive,
diodes D1 and D8 will be on, allowing the positive
side of the modulation envelope or the L - R signal to
develop across the left channel load resistor R1. The
L+R signal which is also present at points 1 and 2,
would also be developed across R1, so that both L+R
and L - Rare present at the left channel output. The
sum of L - R and L+R is 2L or the left channel signal.

During the time B (Fig. 29) when point 1 is negative
and point 2 is positive, diodes D2 and D4 will be on,
allowing the negative side of the modulation envelope
or the -(L - R) signal to develop across the right
channel load resistor R2. The L+R signal would also
develop across R2 so that both L+R and -(L - R) are
present in the right channel output. The sum of L+R
and -(L - R) would be L+R - L+R, or 2R the right
channel signal.

{(L+R and
L-R SIDEBANDS)

Fig. 28 Decoder Operation During Time A

(L + R and
L- R SIDEBANDS)

L+R

-L+R

Fig. 29 Decoder Operation During Time B

RECEIVER TESTS
CHECKING STEREO SEPARATION

RIGHT AND LEFT
CHANNEL
METER LEAD

300 OHMS

ANTENNA

TERMINALS
® ®

SPEAKER
TERMINALS

Fig. 30 SG165 Connected to Receiver for
Separation Test

Many factors can influence a receivers stereo separa-
tion. Antenna signal, IF alignment, stereo decoder
alignment, and even power supply can in some cases,

be responsible for a complaint of poor stereo. The
on the air signal is a poor way of determining a re-
ceivers performance, while a check with SG165 will
quickly indicate the extent of the problem. In most
cases it is not even necessary to remove the receiver
from its cabinet to check its stereo separation with
the SG165.

1. Remove the antenna from the receiver, but
leave the speakers connected. Turn the receiver
volume or loudness control up so that even a weak
signal is audible, and with the receiver’s AFC off,
and all other controls set for a flat audio response,
tune the receiver to a quiet spot on the dial near
98MHz.

2. Turn the receiver power off, remove the speak-
ers, and connect the SG165 left and right channel
meter leads to the receiver speaker terminals. Set
the SG165 SPEAKER LOAD switch to the load re-
quired by the receiver. If the load requirements are
not given, set the switch to the 16 ohm position.
Set the METER WATTS RANGE switch to SEPARA-
TION TEST position.

3. Connect the SG165 ALL SIGNALS OUTPUT to

the antenna terminals of the receiver using the 39G43
matehing pad. For auto radios, use the dummy an-
tenna 39G53. Set the SG165 OUTPUT SELECTOR
to FM RF, and the MODULATION to STD MPX.

4. Adjust the SG165 MICROVOLT OUTPUT con-
trols for 500uV (7 X 100).

5. Switch the LEFT and RIGHT 400Hz switches
ON, and set the PILOT 19KHz switch to 10%.

6. Turn the receiver power on, and adjust the
SG165 RF TUNING control for a maximum indica-
tion on the LEFT and RIGHT CHANNEL OUTPUT
meters. Reduce the receiver volume or loudness con-
trol as necessary to keep the OUTPUT meters below
full scale.

7. Fine tune the receiver as follows:
a. For receivers with a zero center tuning
indicator: Adjust the receivers control tuning
for zero center indication.
b. For receivers with a peak tuning meter:
Adjust the receiver tuning control for a maximum
indication of the tuning meter.

NOTE: On receivers with both a zero center and
peak tuning meter, both indications should coincide.
If they do not, misalignment of the receiver IF
amplifiers or detector is indicated.

c. For receivers with no visible tuning indi-
cator: Adjust the receiver tuning control for a
maximum indication on the SG165 OUTPUT
meters.

8. Adjust the receiver volume or loudness control
and balance control for a full scale (Odb REF) indi-
cation of the LEFT and RIGHT CHANNEL OUT-
PUT meters. NOTE: If it is necessary to adjust the
receiver balance control more than 20% from center,
a defect is indicated either in one of the audio
channels, or in the MPX decoder circuit.

——___ Odb

LEFT OUTPUT RIGHT OUTPUT

Fig. 81 Both Channels On Receiver Adjusted
For Reference

NOTE: If a receiver or tuner is not capable of a full
scale indication on the output meters, refer to the
db section of this manual to measure separation.

9. Alternately turn on and off the LEFT and
RIGHT 400Hz switches, and observe the LEFT and
RIGHT CHANNEL OUTPUT meters. Read the
separation directly in db for the channel with the
400Hz off. The readings for both channels should
be at least 20db, with a maximum difference be-
tween readings of 10db. If poor separation is in-
dicated, refer to Receive Troubleshooting section.

LEFT OUTPUT

RIGHT a wae

Fig. 32 Right Channel Off, Measure Separation

10. Check the effect of the receiver tuning control
on the separation. If better separation is obtained at
some tuning point other than that obtained in step 7,
misalignment of the receiver IF’s or detector is
indicated.

11. Check the “lock in range” of the receiver MPX
circuits by switching the PILOT 19KHz to 5%, and
observing the effect on the receiver separation. A
properly operating receiver should produce nearly
the same separation with the PILOT 19KHz at 5% as
it did with 10% pilot. If difficulty is encountered,
refer to the section of this manual on ALIGNING
A RECEIVERS 19KHz and 38KHz CIRCUITS.

12 You may wish to further evaluate the perfor-

mance of the receiver by repeating the separation
check at 90 and 106MHz.

CHECKING THE SENSITIVITY
OF AN FM RECEIVER

The sensitivity test as made with the SG165 is a
measurement of the signal (measured in microvolts)
necessary to produce a 30Q0db signal plus noise to
noise ratio. Results of this test will be of sufficient
accuracy to compare with the published IHF sen-
sitivity of the receiver for test and troubleshooting
purposes.

The graph in Fig. 33 shows the effect on the level of
the noise and signal outputs of a receiver with respect
to the input signal. Note that the noise decreases and
the signal increases as the input signal increases. At
some point, while the output signal is increasing and
the noise is decreasing, the ratio between them will be

RECEIVER OUTPUT

ee ee

INPUT SIGNAL

Fig. 33 Effect of Input Signal on Receiver
Outputs
31 to 1 (80db). This is the point at which the sensi-
tivity measurement is made. To make the sensitivity
test, proceed as follows:

1. Set up the receiver and the SG165 by making the
connections as detailed in the first three steps of
CHECKING STEREO SEPARATION.

2. Switch the LEFT and RIGHT 400Hz ON and the
PILOT 19KHz to 10%. Set the FM MODULATION
to IHF MPX.

3. With the MICROVOLT OUTPUT controls set for
a low signal level of 100uV or less, fine tune the re-
ceiver as in steps 6 and 7 of CHECKING STEREO
SEPARATION.

NOTE: If it is not possible to eliminate the third
harmonic distortion from the output signal by care-
ful fine tuning, insufficient FM IF band width is in-
dicated. Refer to the FM IF Alignment section of
this manual.

4. Turn the SG165 AC power OFF. Adjust the re-
ceiver volume control for an indication of -30db on
the OUTPUT meters of the SG165.

5. Turn the SG165 AC power ON. Without changing
the control settings of the receiver, adjust the MICRO-
VOLT OUTPUT controls of the SG165 to produce a
full-scale indication of Odb on the OUTPUT meters.

6. Note the setting of the MICROVOLT OUTPUT
controls, and multiply the setting of the coarse con-
trol times the corrected output of the fine control
from Fig. 34. When using the 39G43 pad, or the
39G53 dummy antenna, multiply the result by .5 to
find the actual input signal to the receiver. This is
the sensitivity in microvolts.

CONTROL
SETTING

CORRECTED
OUTPUT

10 10
8.1
6.4
5.1
4.0
3.0
2.4
1.8

No BoB Ff oO ODO HN DO LC

1.4

fat

1.2

Fig. 34 Corrected Microvolt Output

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

CHECKING A RECEIVERS MAXIMUM
RMS POWER OUTPUT

Fig. 35 Point of Amplifier Distortion
The power output measured with the SG165 is the
RMS or true power. There is no 100% accurate for-
mula for converting RMS power to the various mea-
surements used in rating different receivers, however a

good rule of thumb is to multiply the RMS power
for one channel by 4 to find the peak power rating.
The 400Hz audio signal may be injected in a variety
of ways; FM RF, FM IF, AM RF, AM IF, MPX signal
or audio. The following procedure is given since it
does not require removal of the chassis, or any inter-
nal chassis connections.

1. Set up and connect the receiver and SG165 as
in steps 1 through 8 in the CHECKING A RE-
CEIVERS SEPARATION section, except turn the
METER WATTS RANGE to 10 or 100W. ( use
AM RF for checking AM receivers).

2. Connect an oscilloscope to one of the speaker
outputs, and increase the setting of the receiver
volume or loudness control while observing the out-
put waveform, to just below the point where dis-
tortion appears. The SG165 meters indicate the
RMS power. Read the 1 to 10W scale directly for
the 10W range, or multiply by 10 for the 100W range.

CHECKING AN AMPLIFIERS SENSITIVITY
AND RMS POWER OUTPUT

If an amplifier has more than one input (phono,
tape, auxiliary, etc.) each input should be tested for
proper sensitivity separately. If the sensitivity is not
specified, the following table can serve as a guide
for test purposes:

Magnetic phono or tape head 1 - 5mV
Tape, Tape Monitor, Tuner

auxiliary 150 - 250mV
Crystal phono 250 - 750mV

To test an amplifiers sensitivity, proceed as follows:

1. Set the SG165 OUTPUT selector switch to
400Hz SINE WAVE, and the MICROVOLT OUT-
PUT controls fully counterclockwise (1 X1).

2. Turn the receivers volume or loudness control
to maximum, the input selector to the input to be
tested, and all other controls for a flat audio res-
ponse as indicated by front panel markings.

3. Use the 39G43 matching pad and phono
plug to alligator clip leads (supplied) or the optional
39G47 BNC to phono plug cable to connect the
ALL SIGNALS OUTPUT of the SG165 to the input
being tested. Connect the SG165 meter leads and
the vertical input of an oscilloscope to the amplifiers
speaker terminals. Select the correct SPEAKER
LOAD, and POWER RANGE for the amplifier.

4. Gradually increase the MICROVOLT OUTPUT
from the SG165, while observing the speaker output

waveform on the oscilloscope, to just below the point
where noticeable distortion occurs. The SG165
meter now indicates the RMS power output of the
amplifier.

5. To find the input signal in millivolts RMS to
produce this output, multiply the setting of the
coarse MICROVOLT OUTPUT control by .1 and the
result by the corrected output of the vernier MICRO-
VOLT OUTPUT control from the table below. If
ah 39G43 pad is being used, multiply this result
y .D.

CONTROL SETTING CORRECTED OUTPUT

orrNwO BO Or
NANAK wow oO

Pm Ww eR OVO 100 0

on
>

NOTE: Output level specifications only valid when
ALL SIGNALS OUTPUT terminated in 75 ohms.

SQUARE WAVE TESTING
OF AUDIO AMPLIFIERS

For a complete evaluation of an audio system, some
method of determining frequency response, and
effectiveness of tone controls is necessary. This
evaluation can take the form of a complete plot of
the sine wave frequency response, which is time
consuming, or the analysis of the systems response to
a square wave input. The 400Hz square wave output
of the SG165 is ideal for testing any audio system.
High frequency performance is indicated by the
response to the leading edge of the square wave, and
low frequency performance by the tilt to the top of
the square wave. The following drawings and expla-
nations are normal for the amplifier control settings
indicated. All front panel controls that would affect
the audio response are adjusted for a flat response, as
indicated by front panel markings, unless otherwise
noted.

Fig. 36 shows an amplifier response to the 400Hz
square wave through the normal uncompensated
inputs such as tuner, auxiliary, or tape monitor.
Note that the square wave is nearly perfect indicating
a flat amplifier response.

Fig. 36 Auxiliary Input
Fig. 37 shows an amplifiers response through a mag-
netic phono input. Note that the square wave has a
definite slope. This is the normal response for a
magnetic phono input compensated for the standard
RIAA playback curves.

Fig. 37 Magnetic Phone Input
Fig. 38 shows an amplifiers response through a crys-
tal phono input. Note that the square wave has the
slope of the RIAA playback curve, and that in addit-
ion there is a peak on the leading edge. The peak on
the leading edge indicates a high frequency boost to
compensate for the normally lower high frequency
response of the crystal type of cartridge.

Fig. 38 Crystal Phono Input

Fig. 39 shows an amplifiers response through the aux-
iliary input with the base control adjusted for maxi-
mum boost. Note that the square wave has an up-
ward slope, indicating greater amplification to lower
frequencies. Also note that the corner of the leading
edge is square, indicating normal high frequency
response.

Fig.39 Auxiliary Input, Base Control Adjusted
For Maximum Boost

Fig. 40 shows an amplifiers response through the
auxiliary input with the base control adjusted to
minimum. Note that the square wave has an expo-
nential downward slope indicating less amplification
to lower frequencies. Also note that the leading
edge is square indicating normal high frequency res-
ponse.

Fig. 40 Auxiliary Input, Base Controls Adjusted

to Minimum
Fig. 41 shows an amplifiers response through the
auxiliary input, with the treble control adjusted for
maximum boost. Note that the square wave has a
large spike on the leading edge, indicating increased
amplification to higher frequencies. Also note that
the top of the square wave is flat, indicating normal
response to low frequencies.

ee a a aS ne

Fig. 41
for Maximum Boost

Auxiliary Input, Treble Control Adjusted

Fig. 42 shows an amplifiers response through the
auxiliary input with the treble control adjusted to
minimum. Note that the leading edge of the square
wave is rounded, indicating less amplification to
higher frequencies. Also note that the top of the
square wave is flat, indicating normal response to
low frequencies.

Fig.42 Auxiliary Input, Treble Control Adjusted

to Minimum
Fig. 43 shows an amplifiers response through the
auxiliary input, with the low or “rumble’’ filter
engaged. Note that the top of the square wave has a
downward slope, that extends nearly to the zero re-
ference line indicating that the low filter effects
lower frequencies than the base tone control.

Fig. 43 Auxiliary Input, Low Filter On

Fig. 44 shows an amplifiers response through the
auxiliary input, with the high or “‘hiss’”’ engaged.
Note that just the very corner of the leading edge of
the square wave is rounded, indicating that the high
filter effects higher frequencies than the treble con-
trol.

|
|

Fig. 44 Auxiliary Input, High Filter On
Fig. 45 and Fig. 46 show an amplifiers response
through the auxiliary input with the loudness contour
on, at two different volume control settings. Note
that in Fig. 45 with the volume control at 25% the
top of the square wave has an upward slope, indicating
increased response to low frequencies. Note also that
the leading edge of the square wave retains its normal
rise, indicating a normal or slightly increased response

Fig. 45 Auxiliary Input, Loudness Contour On,
Volume Control at 25%

to higher frequencies. The loudness contour is
intended to compensate for the human ears reduced
sensitivity to low frequencies at low volume levels.
As the volume control is advanced toward maximum,
the effect of this control diminishes until with the
volume control at maximum (Fig. 46) the normal
square wave indicated a flat amplifier response.

Fig. 46 Auxiliary Input, Loudness Contour On,
Volume Control Near Maximum

TESTING 4 CHANNEL OR QUAD SYSTEMS

At present, all four channel systems are either dis-
crete four channel tape, or some form of audio
matrix or phase shift circuit. The discrete four
channel systems may be tested using the same square
wave, sensitivity, and maximum power output tests
as conventional audio amplifiers. Just remember to
load all four channels with speakers or load resistors
of the proper impedance.

To demonstrate the ability of the SG165 in testing
four channel systems the waveforms in Fig. 47 were
taken from the speaker terminals of a receiver using
the SQ system. The SG165 was set to FM RF and
connected to the receivers antenna terminals. For
comparison purposes, the oscilloscope vertical input
controls remain identical and unchanged for this
series of photos.

NOTE: Other systems will produce different outputs.

Check manufacturers literature for specific informa-
tion.

Fig. 47 Outputs of SQ Quad system

In the first column of photos, Channel A (upper
trace) is connected to the Right Front (RF) speaker,
and channel B (lower trace) is connected to the
Right Rear (RR). In the second column, Channel A
is connected to Left Front (LF), and Channel B to
Left Rear (LR). In the third column, Channel A is
connected to Right Rear (RR), and Channel B is
connected to Left Rear (LR). For the first photo in
each column, both the LEFT and RIGHT 400Hz
signals are ON, for the second, the RIGHT is ON
and the LEFT is OFF, and for the third, the RIGHT
is OFF and the LEFT is ON.

The third column of photos (rear channels) would be
best for evaluating the performance of the SQ matrix.
Note that in the first photo (LFET and RIGHT 400

Hz ON) the RR and LR signals are 180 degrees out
of phase, in the second photo (RIGHT ON, LEFT
OFF) the LR lags the RR by approximately 30
degrees, and in the third photo, (RIGHT OFF, LEFT
ON) the LR leads the RR by approximately 30
degrees. It is also interesting to note by comparing
the A trace in the first column of photos that the
front channel separation is reduced from the 35db of
the receiver in normal 2 channel operation to approx-
imately 8db in SQ operation.

RECEIVER ALIGNMENT —
FM IF ALIGNMENT

The alignment of the IF amplifiers in the Stereo FM
receiver is much more critical than in the mono

nect the red lead of the 39G45 detector probe to
the cathode output of one of the detector diodes
(TPA), and the black lead to ground. Plug the 39G44
detector cable into the FROM DETECTOR jack on
the SG165.

4. Use the 39G43 pad to connect the ALL SIG-
NALS OUTPUT of the SG165 to the input of the
mixer. Connect the red lead to the input of the
mixer and the black lead to ground.

5. Adjust the IF interstage transformers, A 1 to
A4, and the primary of the detector transformer,
Ad, for a response curve as shown in Fig. 48A. The
peak of the curve should fall at 10.7MHz, and the
10.6MHz and 10.8MHz limit markers should be at
least 90% on the curve. Adjust the MICROVOLT
OUTPUT controls to inject just enough signal for a
noise free response curve.

6. Reconnect the electrolytic capacitor and con-
nect the red lead of the 39G45 detector probe to
the audio output test point. (TPB)

7. Adjust the secondary of the detector transformer
A6, for the Symetrical “‘S” curve as shown in Fig. 48B.
Retouch the primary of the detector transformer,
A5, to obtain the best possible curve.

ALIGNING FM IF’S CONTAINING
CRYSTAL FILTERS

The tuner shown in Fig. 49, is a good example of the
latest trend in FM receivers. In place of the 3 or 4 IF
stages followed by a ratio detector, this receiver uses
a transistor as the first IF followed bv a ceramic
filter to determine band width, and an IC that is a
combination detector, limiter, and 5Q0db gain IF
amplifier. The alignment procedure for this system
is actually simpler, as it contains fewer adjustments

BLACK TO
GROUND

CONNECTED

TO SG165
ALL SIGNALS OUTPUT

Fig.49 Crystal Filter FM IF Circuit

than the standard system. The major difference from
an alignment standpoint is that the operating frequency
of the system may not be exactly 10.7MHz. The
actual operating frequency will fall between 10.625
MHz and 10.775MHz, and is determined by the pro-
duction variations in the ceramic filter. The IC
itself presents no alignment difficulties, as the circuit
contains only one adjustment. This coil, connected
externally to the IC, performs the same detector
balance adjustment as the secondary of the ratio de-
tector transformer and is adjusted for the proper
“S”’ curve.

1. Tune the receiver to a quiet spot on the dial,
connect the SG165 SPEAKER LOADS in place of
the receivers speakers, and set the SG165 OUTPUT
selector switch to the 10.7MHz SWEEP and MARK-
ERS position.

2. Use the 39G43 matching pad to connect the
SG165 ALL SIGNALS OUTPUT to the input of the
mixer (red lead to the input, black to ground). Ad-
just the SG165 MICROVOLT OUTPUT controls
for approximately 10mV. (10X100)

3. Use the phono plug to alligator clip lead pro-
vided to connect the TO SCOPE jack to the vertical
input of an oscilloscope. Set the oscilloscope hori-
zontal frequency control to the internal 60Hz posi-
tion, and adjust the oscilloscope phase control for
a pattern with no indication of fold over.

4. Plug the 39G45 detector cable into the FROM
DETECTOR jack on the SG165, and connect the
blue lead (detector) to test point V, black lead to
ground.

5. Us the AM/FM IF ROCKER to center the
response on the sweep and adjust Tl for maximum
gain and symmetry similar to Fig. 48A.

IC LIMITER & DETECTOR

FM AUDIO

6. Adjust the oscilloscopes horizontal position
control to center the peak of the response on the
major vertical grid line. Do this carefully, as this
establishes the IF center frequency for step 7.

7. Remove the 39G45 from test point V, and
connect the red lead to test point Z, the composite
FM audio output. Adjust L1 for maximum ‘“S”
curve amplitude and symmetry similar to Fig. 48B, so
that the curve crosses the base line at the major ver-
tical grid line that was established as the center fre-
quency of the IF in step 6.

FM RF ALIGNMENT

There are as many variations in FM RF circuits as
there are receivers on the market. FM RF adjustments
are usually located in three places: on the input of
the RF amplifier, the input of the mixer, and the
local oscillator. The adjustments take the form ofa
trimmer capacitor and/or an adjustable coil slug.
Either or both forms of adjustment may be found in
any of the three locations. If both forms of adjust-
ment are present at a given location, the coil should
be adjusted at a frequency near the low end of the
band and the trimmer adjusted at a frequency near
the high end of the band. If only one adjustment is

uf CiA CI

present in a given location, it will be necessary to
optimize its adjustment for best receiver perfor-
mance across the band. Though it is best to follow
the manufacturers procedure if available, the proce-
dure below is typical for most popular FM receivers.

HOOK UP

1. Connect the SG165 ALL SIGNALS OUTPUT to
the receivers antenna terminals using the red and
green leads of the 39G43 matching pad. For auto
radios, use the 39G53 dummy antenna.

2. Connect the SG165 SPEAKER LOADS in place
of the receiver speakers, set the SPEAKER LOAD
switch to the correct load resistance, and set the
POWER RANGE switch to the SEPARATION TEST
position. Switch the receiver AFC off.

3. Set the SG165 OUTPUT Selector to FM RF,
the FM MODULATION switch to STD MPX, switch
the LEFT and RIGHT 400Hz on, and set the
19KHz PILOT to zero. Use the lowest output
setting of the MICROVOLT OUTPUT control that
will produce a usable indication on the output meter.

Tan +

9643

l
L2
UO
O
G
ae]

TO SG165
ALL SIGNALS OUTPUT

sf] CIE! CIF

RF | IF DETEC
AMP- MIXER re &
LIFIER DEC
REEN
A

LEFT |
sie
RIGHT
poke

TO SG165
SPEAKER
LOADS

Fig. 50 Typical FM RF Circuit

29°

STEP RECEIVER SG165 ADJUSTMENT ADJUST FOR
TUNING FREQUENCY

OSCILLATOR ADJUSTMENTS

4 108MHz 108MHz C1A Maximum indication on LEFT
and RIGHT CHANNEL OUT-
PUT meters.

5 88MHz 88MHz L1 Maximum indication on LEFT
and RIGHT CHANNEL OUT-
PUT meters.

6. Repeat steps 4 and 5 until the receiver tunes properly at 88 and 108MHz.

RF SENSITIVITY ADJUSTMENTS

7 108MHz 108MHz C1C, C1E Maximum indication on LEFT
and RIGHT CHANNEL OUT-
PUT meters.

8 88MHz 88mHz L2,L3 Maximum indication on LEFT
and RIGHT CHANNEL OUT-
PUT meters.

9 Repeat steps 7 and 8 until no further improvement can be obtained in the
receiver sensitivity.

FM STEREO SEPARATION ADJUSTMENTS

IF COMP

GREEN
AUDIO
AMP
2 | BLACK ' i i \ '
O | NOT
© | USED 19KHz DOUB- 38KHz a SEPARATION
AMP LER AMP MPX ADJUSTMENT
i DECODER (IF USED)
TO SG165

ALL SIGNALS OUTPUT

AUDIO
AMP

TO SG165
OUTPUT
METERS

Fig. 51 Typical Stereo Decoder Circuit

RED TO 1ST
INPUT O IF
MIXER
0.7 10.8
GREEN
NOT

CONNECTED

‘TO SG165
ALL SIGNALS OUTPUT

PRIMARY

A6 ~~ SECONDARY
CRI

B OUTPUT oor
TPB TPA

Fig. 48 Standard 10.7MHz IF Circuit

receiver. The difference is much the same as in color
TV versus black and white TV. The multiplexed
stereo signal requires a greater receiver band width,
and more linear phase and frequency response than
was required by the mono receiver. The SG165 pro-
vides both a 10.7MHz crystal signal for peak align-
ment and a 10.7MHz sweep signal with markers for
sweep alignment of the FM IF amplifiers.

FM IF ALIGNMENT USING 10.7MHz CW (NOT
RECOMMENDED FOR STEREO RECEIVERS)

1. Tune the receiver to a quiet spot on the dial,
connect the SG165 SPEAKER LOAD in place of the
receiver speaker, and set the SG165 OUTPUT selec-
tor switch to the 10.7MHz CRYSTAL CONTROL-
LED position.

2. Use the 39G43 pad to connect the ALL SIG-
NALS OUTPUT of the SG165 to the input of the
mixer. Connect the red lead to the input of the
mixer and the black lead to ground.

3. Connect the positive input lead of a FET meter
to the audio output (TPB). Use a 100K resistor in
series with the lead.

4, Detune the secondary of the detector transfor-
mer to produce a positive indication on the FET
meter. Reduce the SG165 MICROVOLT OUTPUT
controls as necessary to produce a maximum indica-
tion of .5 volts on the FET meter.

5. Adjust the FM IF inter-stage transformers (A1 -
A4) and the primary of the detector transformer (A5)
for a maximum positive indication on the FET meter.
Reduce the setting of the SG165 MICROVOLT OUT-
PUT controls as necessary to maintain a .5 volt
indication.

6. Momentarily disconnect the FET meter and
adjust it for a zero center indication on the plus and
minus .5 volt range.

7. Reconnect the FET meter to the audio output
test. point, and adjust the secondary of the detector
transformer (A6) for a zero center indication on the
FET meter. An approximately equal positive and ne-
gative indication should appear on either side of the
correct setting.

FM IF ALIGNMENT USING 10.7MHz SWEEP AND
MARKERS (BEST FOR STEREO) (Refer to Fig.48)

1. Tune the receiver to a quiet spot on the dial,
connect the SG165 SPEAKER LOADS in place of the
receivers speakers, and adjust the receiver volume or
loudness control to minimum. Set the SG165 OUT-
PUT selector switch to the 10.7MHz SWEEP and
MARKERS position.

2. Use the phone plug to clip lead to connect the
TO SCOPE jack on the SG165 to the vertical input of
an oscilloscope, and set the scope vertical gain con-
trols for .5 volts per inch, or .2 volts per cm. Tum
the oscilloscope horizontal frequency switch to the
60 cycle line sweep position, and adjust the scope’s
line sweep phase control for a pattern with no indi-
cation of foldover. Adjust the AM/FM IF ROCKER
to center the markers on the trace. NOTE: A BNC
to phone plug cable (39G47) is available from any
Sencore regional office to connect the TO SCOPE
jack directly to the vertical input of any scope with a
es connection. The price of the cable is
.0O.

3. Temporarily disconnect the electroyltic capac-
itor, C3, from across the detector load resistors, con-

3. Turn the receiver volume or loudness control to
mid-range and adjust the SG165 MICROVOLT OUT-
PUT controls for a mid scale indication on the SG165
OUTPUT meters.

PEAK ALIGNMENT

1. Set the SG165 AM/FM IF ROCKER control to
the normal center position.

2. Adjust the receiver mixer output transformer,
Al and A2, and IF interstang transformers, A3, A4,
A5 and A6, for a maximum indication on the SG165
OUTPUT meters. Reduce the SG165 MICROVOLT
OUTPUT controls as necessary to maintain a near
mid scale indication of the meters.

STAGGER TUNING

1. Set the SG165 AM/FM Rocker control 15
degrees clockwise from the normal center position
(approximately 5KHz above normal IF frequency).

2. Adjust all stage input transformers, A2, A3, and
A6, for a maximum indication on the SG165 OUT-
PUT meters. Use the SG165 MICROVOLT OUTPUT
controls to maintain a near mid scale indication on
the meters.

L2
cic CiD

(alot

TO SG165
ALL SIGNALS OUTPUT

3. Set the SG165 AM/FM ROCKER control 15
degrees counterclockwise from the normal center
position (approximately 5KHz below the normal IF
frequency).

4. Adjust all stage output transformers, Al, A3,
and Ad, for a maximum indication on the SG165
OUTPUT meters. Use the SG165 MICROVOLT
OUTPUT controls to maintain a near mid scale indi-
cation on the meters.

AM RF ALIGNMENT

The front ends of AM receivers range from the very
simple single transistor oscillator mixer combination
to more elaborate systems involving one or more RF
amplifiers, and separate oscillator and mixer stages.
AM RF adjustments are located in three places: The
antenna circuit, the output of the RF amplifier (if
used), and the local oscillator. The adjustments can
take the form of a trimmer capacitor and/or an ad-
justable coil. If both forms of adjustment are pre-
sent in a given location, then the capacitor is adjusted
for best response to a frequency near the high end of
the band, and the coil adjusted for a frequency near
the low end of the band. If only one adjustment is
present in a given location, it will be necessary to

IN STEREO

RECEIVERS TO SG165

SPEAKER
LOADS

Fig. 53 Typical AM RF Circuit

optimize its adjustment for best performance across
the band. The best procedure in all cases is to follow
the manufacturers instructions.

HOOK UP

1. Set the SG165 OUTPUT selector switch to the
AM RF position, and the AM MODULATION switch
to 30%.

2. Allow the signal from the SG165 to radiate into
the receiver by laying the 39G43 matching pad near
the receiver rod antenna and set the SG165 MICRO-
VOLT OUTPUT controls fully clockwise. For auto

radios, plug the 39G53 dummy antenna connector
into the antenna jack, and set the SG165 MICRO-
VOLT OUTPUT controls for 500uV (5 X 10).

3. Connect the SG165 SPEAKER LOADS in
place of the receiver speakers, tum the POWER
RANGE switch to the SEPARATION TEST position,
and set the receiver volume control to maximum.
(Even though the SG165 meters will Bek be damaged

‘by momentary overloads, it is a good idea to reduce

the setting of the receiver volume control when tuning
across strong local stations). Use the SG165 MICRO-
VOLT OUTPUT controls to maintain a near midscale
indication during the alignment procedure.

STEP RECEIVER SG165 ADJUSTMENT ADJUST FOR
TUNING FREQUENCY

OSCILLATOR ADJUSTMENTS

4 1600KHz 1600KHz C1D Maximum indication on
LEFT and RIGHT CHAN-
NEL OUTPUT meters.

5 550KHz 550KHz L2 Maximum indication on
LEFT and RIGHT CHAN-
NEL OUTPUT meters.

6 Repeat steps 4 and 5 until the receiver tunes properly at 550KHz and

1600KHz.

RF SENSITIVITY ADJUSTMENTS

7 550KHz 550KHz Tl Maximum indication on
LEFT and RIGHT CHAN-
NEL OUTPUT meters

cLa

8 1000KHz 1000KHz 1B Maximum indication on
LEFT and RIGHT CHAN-
NEL OUTPUT meters.

9 1600KHz 1600KHz C1E Maximum indication on
LEFT and RIGHT CHAN-
NEL OUTPUT meters.

10 Repeat steps 7, 8, and 9 until no further improvement in the receivers

sensitivity can be obtained.

‘.

The most common reason for poor stereo separation

is misadjustment of the receivers 19KHz and 38KHz
circuits. The phase relationship for proper stereo is
very important, and even a 10% phase error on the
38KHz signal will nearly eliminate the stereo effect.
The SG165 provides a quick concise way to accurate-
ly adjust these circuits.

1. Set up the SG165 and adjust the receiver the
same as for checking separation.

2. Connect an oscilloscope, or FET meter set to
measure AC volts to the output of the secondary of
the last 38KHz transformer.

3. Adjust the receiver 19KHz and 38KHz coils
for a maximum indication on the scope or meter.
Remove the scope or meter from the output of the
38KHz transformer.

4. Tum the SG165 LEFT 400Hz off and the
RIGHT 400Hz on, and observe the LEFT CHANNEL
OUTPUT meter. Adjust the receiver 19KHz and
38KHz coils for a minimum indication on the meter.
Make these adjustments carefully, turning all adjust-
ments a small amount, rather than one a great deal.

5. Turn the LEFT 400Hz on and the RIGHT 400
Hz off, and observe the RIGHT CHANNEL OUTPUT
meter. Adjust the receiver 19KHz and 38KHz coils
for a minimum meter indication. Make these ad-
justments carefully, turning all adjustmenst a small
amount, rather than one a great deal.

6. Repeat steps 4 and 5 until equal and maximum
separation between channels is obtained.

7. If the receiver has a separation or balance ad-
justment in the decoder, adjust this control for
optimum separation on both channels.

8. If proper separation cannot be obtained, refer to
section on Receiver Troubleshooting.

9G43

TO SG165
ALL SIGNALS OUTPUT

Al i A3 i . as
CON- 1ST 2ND
RED VERTER IF IF
! A2 A4
oo)

AM IF ALIGNMENT

The hook-up for aligning the IF amplifiers of any
AM receiver is basically the same. Most receivers
require a simple, all stages tuned to the same fre-
quency “peak” alignment, however, some may re-
quire stagger tuning to obtain the required band
width and prevent oscillation. If service information
is not available, the best procedure is to peak align
the receiver, and then check the receiver performance.
If the receiver exhibits poor high frequency response,
and tends to motorboat or oscillate, the receiver
should be realigned using the stagger tuning proce-
dure. Stagger tuning involves tuning the input and
output of a stage to slightly different frequencies,
thereby increasing the band width of the stage, and
preventing the stage from acting as a tuned plate,
tuned grid oscillator. Other receivers that require
special treatment of the IF alignment are those using
ceramic or crystal filters. The filter used in these
receivers may operate at a slightly different frequency
than the standard 455 or 262KHz, and the receiver
IF adjustments must be adjusted to the natural reso-
nant frequency of the particular filter used.

HOOK UP FOR AM IF ALIGNMENT

1. Tune the receiver to a quiet spot on the band,
connect the SG165 speaker loads in place of the
speakers, and tum the POWER RANGE switch
to SEPARATION TEST. Set the SG165 OUTPUT
selector switch to either 455KHz or 262KHz position
as required.

2. Loosely couple the output of the SG165 to the
input of the AM mixer stage. Loose coupling may be
accomplished either by clipping the red lead of the
39G43 to the body of a resistor in the input of the
mixer, or by connecting a 1000 ohm resistor in series
with the red lead of the 39G43 to the input of the
mixer. Set the SG165 AM OUTPUT MODULA-
TION switch to 30%

AUDIO TO SG165
AMP SPEAKER
FOR LOADS
STEREO

Fig. 52 Typical AM IF circuit

RECEIVER TROUBLESHOOTING

RECEIVER BLOCK DIAGRAM

The following block diagrams, waveforms, and tables
provide a quick reference to the waveforms at differ-
ent locations in AM and FM receivers, along with the
correct settings of the SG165 to inject signals at the
various points. No attempt has been made to indicate
signal levels, except that in general the signal level

necessary to maintain the same audio output should
decrease for each additional stage of amplification

between the point of injection and the output. For
example, it should take less signal to drive the input
of the second FM IF than it took to drive the input of
the third FM IF.

The numbered waveforms are taken at the numbered
testpoints in the receiver block diagrams.

The following table indicates the correct settings of the SG165 controls for injection into the numbered points on

the block diagram.
POINT SG165 OUTPUT MODULATION STEREO MPX CONTROLS NOTES
1 FM RF STD MPX LEFT 400Hz OFF; RIGHT 1
400Hz ON 19KHz PILOT
10%
2 10.7MHz IF STD MPX LEFT 400Hz OFF; RIGHT 1
400Hz ON 19KHz PILOT.
10%
3 MPX SIGNAL IHF MPX LEFT 400Hz OFF; RIGHT 2
400Hz ON 19KHz PILOT
10%
4 MPX SIGNAL IHF MPX LEFT 400Hz OFF; RIGHT 2
400Hz OFF 19KHz PILOT
10%
5&6 400Hz SINE WAVE or 400Hz SQUARE WAVE
7 AM RF 30% NOT USED 1
8 455KHz IF or 30% NOT USED 1
262KHz IF
NOTES:

1. Both RF and IF signals should pass through the input of the mixer stage.

2. When using the MPX SIGNAL output of the SG165, the output level will be 30% of normal if the MODULA-

TION switch is in the STD MPX position.

3. The level of the OFF channel signal will be lower than the ON channel depending on the stereo separation of

the receiver.

4, The waveform shown for point 9 would be for the input of the AM detector.

AMP aa

Osc \2/ | AUDIO | | :
\t/ PRE AUDIO AUDIO
OUTPUT

RF MIXER 1ST 2ND 3RD FM COMP MPX z

AMP IF IF IF DET
®
> PRE AUDIO AUDIO
/i\ /3\ i9 @ AMP AMP OUTPUT
19KHz DOUBLER 38KHz
AMP AMP <a

Fig. 54A Block Diagram FM Stereo Receiver

AUDIO

oe) pee rom 4 a
ls — 7” 1 SECOND AUDIO CHANNEL
“4 ar L-4 ra-< | IN.AM/FM STEREO
7 | rl ' ‘ RECEIVERS ONLY
SE Bae © tke | Megs et ok
N

r
!
- osc \w/ :
|
!
1
1

1ST 2ND
IF IF

RECEIVER TROUBLE CHARTS

RECEIVER DEAD

DO PILOT LIGHTS LIGHT?

Conclusion:
Check Fuse and AC
power connections

YES
Check B+ and/or B-

voltages; are they OK?

NO
Conclusion:
Troubleshoot power

supply

YES
Inject 400Hz sine at input
of audio output stage. Do
you hear sound from speaker?

NO
Conclusion:
Check and replace as
necessary output, driver,
pre-driver or speaker

YES

Inject 400Hz sine at out-
put of DET. Do you hear
tone?

Conclusion:
Follow procedure for AM
or FM dead

NO STEREO RECEPTION

Follow procedure for ADJUSTING RECEIVER
19KHz & 38KHz circuits. Do you have 38KHz
age

NO si ie. YES

Starting with 19KHz take Is composite signal (photo

off coil; troubleshoot with Bbdisiuil Ht mel vice at left) present at center

scope to locate problem a wii mire fi i tap of 38KHz output tran-
1, sformer. (1 channel ON)

1"
yyy iN

NO YES

Conclusion:
Suspect composite amp

Suspect decoder.

(FOLD OUT FOR BLOCK DIAGRAM)
35

AM OR FM DEAD OR VERY WEAK

Inject 400Hz audio into output of detector.
Is signal present at output of receiver?

Conclusion:
Check wiring to function switch
or preamplifier if used

Check and replace detector
or detector transformer as
necessary

Conclusion:
Defect in last IF stage

Conclusion:
Repair defective IF stage

Set the receiver dial to a station
near the low end of the band, and
inject the SG165 set for a frequency
equal to the station frequency plus
the eseillatien frequency with the
modulation OFF into mixer. If
station signal is received, defect is in
receiver local oscillator.

YES

Inject IF signal to input of
detector. Is signal (weak)
observed at output receiver?

YES

Inject IF signal into input of
last IF stage. Is signal much
stronger?

YES

Reduce SG165 MICROVOLT
OUTPUT until signal is weak at
output, and inject into input of
preceeding IF stage. Repeat for
each IF stage and the mixer stage.
Do all IF stages including the mix-
er have gain?

YES

Inject an RF signal into input
of mixer, and tune the receiver.
Is signal present at amplifier
and receiver?

YES

Inject RF signal into input of RF
amplifier (if used). Does RF amp
have normal gain?

(Cont. on next page)

ET rn eet See ne a eer ce ae eee ap ae en ee ne ene ee ee eee ee

eT Ma TRE eee Ne ng TT ee ee FO Te ee ee ee ee ee eg ae eg a ee ee eS Eee Ne te pe te ee TE a, eee ie Te Pe ag gts ae ET Ee Ngee | tage age Foe tae ee Pe ren a eT oe
: sae te ieee a a ee

NO YES

Conclusion: Conclusion:
Repair RF amplifier Check antenna and input
circuits

NOTE: In some cases a defective local oscillator
will be shocked into oscillation during trouble-
shooting procedures. If this happens, turn the re-
ceiver off and on to see if it will quit again.

I a

POOR FREQUENCY RESPONSE

Is problem evident in all functions?

NO YES

Do substitute speakers cure problem?

Conclusion:

If problem is in AM or FM function
check RF & IF alignment of affected
section. If alignment proves correct,
inject 400Hz square wave at input of
affected function, and use scope to
locate stage causing problem. (Refer
to Square Wave Testing of Audio
Amplifiers)

YES

Are power supply output voltages Replace speakers

and ripple normal?

Conclusion: Ne . YES
Repair power supply
Inject 400Hz square wave into.

Aux. or TAPE MON input, and
use scope to locate defective stage.

DB TABLE

HOW TO USE THE DB TABLE: DB VOLTAGE OR ss
ma DB
The db table of Fig. shows the relationship be- 1.000 0 1.000
tween db and the ratio of two voltages across a 944] 5 1.059
fixed impedance. The db values are listed in the 8913 1.0 1.122
center column, the ratios corresponding to a de- .7943 2.0 1.259
crease in signal level (-db) are listed in the left hand .7089 3.0 1.4138
column, and the ratios corresponding to an increase .6310 4.0 1.585
in signal level (+db) are listed in the right hand .0623 5.0 1.778
column. .5012 6.0 1.995
4467 7.0 2.239
FOR 30db SIGNAL PLUS NOISE TO NOISE 3981 8.0 2.412
MEASUREMENT (Increase in signal) 3548 9.0 2.818
.3162 10.0 3.162
1. Measure the peak to peak amplitude of the .2512 12.0 3.981
noise signal. 1995 14.0 5.012
1585 16.0 6.310
2. Since this measurement is a 30db increase, refer 1259 18.0 7.943
to the +db column to find the ratio of 31.62 to 1. 1 20.0 10
.05623 25.0 17.78
3. Multiply the amplitude of the noise signal mea- .03162 30.0 31.62
sured in step 1 by the ratio from step 2. .01778 35.0 56.23
OL 40.0 100
For example if the noise signal measures .2v p-p, .005623 45.0 177.8
the signal level necessary for a 30db increase would .003162 50.0 316.2

be .1 X 31.62 or 3.162v p-p.
FOR SEPARATION MEASURE (decrease in signal)

1. Measure the peak to peak amplitude of the
amplifier or tuner output signal with both channels
on.

2. Switch one channel off, and measure the peak to
peak amplitude of the off channel output signal.

3. Divide the amplitude measured with the signal
off (small number) by the amplitude measured with
the signal on (large number).

4, Find the -db voltage ratio in the left column of
the db table closest to the ratio calculated in step 3.
The db listing corresponding to this ratio is the sepa-
ration of the receiver or tuner, measured in db.

SERVICING YOUR $6165

DISASSEMBLY INSTRUCTIONS

CASE WRAP

1. Remove the two screws from the top of the case
wrap, and the two from each side of the wrap near
the bottom.

2. Remove the cables from the lead compartment,
and dress them so that they are hanging free from the
back of the instrument.

3. Spread the bottom front of the case wrap slight-
ly, and lift the wrap straight up. Guide the cables
through the opening in the floor of the lead compart-
ment one at a time.

SHIELD COVER
(case wrap removed)

1. Disconnect the molex plug carrying the power
supply outputs from the feedthrough capacitors on
the side of the main shielded assembly.

2. Leave the power supply and fuse bracket mount-
ed to the shield cover, and remove the four sheet me-
tal screws that secure the cover to the shielded
assembly.

3. Spread the bottom of the shield cover, and lift
it straight up. Take care that the shield cover clears
the MPX PC board, SPEAKER LOAD switch, and
the POWER RANGE switch.

4. Place the shield cover next to the SG165 so that
the fuse holder bracket faces in the same direction as
the front of the SG165, and reconnect the molex
plug disconnected in step 1. Take care to plug the
supply output cable into the feed through terminals
correctly. The SG165 is now ready to troubleshoot
using the coil and component side PC board layouts.

5. When replacing the shield cover, take care that
the spring fingers mounted to the shield cover line up
properly with the edge of the shielded assembly.

REMOVING THE MAIN RF BOARD FOR
COMPONENT CHANGE
(case wrap and shield cover removed)

1. Remove the knobs from the OUTPUT selector
switch, the AM/FM IF ROCKER control, and the
MICROVOLT OUTPUT controls.

2. Use a long, small, thin bladed screwdriver to
loosen both set screws that secure the shaft of the
RF TUNING capacitor to the front panel mounted
4:1 drive.

3. Remove the molex connectors from the side of
the shield assembly and the phono plug from the
front of the assembly.

4. Remove the four screws that secure the shielded
assembly from the bottom of the case.

5. Pull the shield assembly straight back until the
shaft of the RF TUNING capacitor clears the front
panel drive, and then lift it up and out of the case.

6. Remove the screw, nut and spacer that secure
the 2,000mfd electrolytic capacitor to the shield
assembly. Reassemble the screw, nut and spacer to
the capacitor mounting strap to prevent loss of the
individual pieces.

7. Remove all molex connectors and the phono
plug from the RF board.

8. Remove the four screws that secure the RF
board to the shield assembly, and the three machine
screws that secure the RF TUNING capacitor to the
front of the shield assembly.

9. Lift the rear of the RF board, and pull back
until the shafts of the OUTPUT selector switch and
the RF TUNING capacitor clear the holes in the
shield assembly.

REMOVING THE ATTENUATOR
(case wrap, shield cover and RF board removed)

1. Remove the three sheet metal screws that secure
the cover of the attenuator, and remove the cover.

2. Unsolder the wires from the phone plug to the
input of the stepped attanuator and from the variable
attenuator to the output of the stepped attenuator.

3. Remove the %”’ nut and lock washer that secure
the stepped attenuator to the shield assembly, and
lift the stepped attenuator up and out of the shield.
Take care that the wire from the output of the stepped
attenuator clears the hole in the shield.

4. Unsolder the wire from the output of the variable
attenuator to the output phono jack, and remove the
¥”” nut and lockwasher that secure the variable atten-
uator to the shield. Remove the variable attenuator.

REMOVING THE MPX BOARD

(case wrap removed)

1. Unplug the molex connector that connects the
MPX board to the feed through capacitors on the side
of the shield assembly, and dress this cable over the
top of the power supply PC Board.

2. Remove the two screws that secure the MPX
board to the front panel mounted stand offs.

3. Remove the two 4” nuts that secure the MPX
board bracket to the two lower meter mounting
studs, and pull the top of the MPX board off the
studs. Lift the MPX board up and away from the
front panel.

§6165 CALIBRATION INSTRUCTIONS

NOTE: ADJUSTMENTS MARKED WITH AN *
REQUIRE SPECIAL EQUIPMENT TO ADJUST,
AND SHOULD NOT BE ATTEMPTED UNLESS
THIS EQUIPMENT IS AVAILABLE.

POWER SUPPLY

1. Measure voltage on positive lead of C105.

2. Adjust R113 for a negative voltage of
equal value as measured at the negative lead of
C106.

400Hz SINE WAVE

1. Tum the OUTPUT selector switch to the
400Hz SINE WAVE position.

2. Connect an oscilloscope or meter set to
measure AC volts to the ALL SIGNALS OUTPUT
of the SG165. Set the MICROVOLT OUTPUT
controls for maximum output.

3. Adjust R375 (PC control on board mounted
to side of tuning capacitor) for 1 V RMS (2.8v
Pp-p).

67KHz*

1. Turn the OUTPUT selector switch to the
67KHz position.

2. Connect a frequency counter to the ALL
SIGNALS OUTPUT of the SG165. Set the
MICROVOLT OUTPUT controls for maximum
output.

3. Adjust L807, the 67KHz oscillator coil,
for an output frequency of 67KHz.

Fig. 54 SG165 Power Supply Adjustments

MPX (STEREO SEPARATION ADJUSTMENT)

1. Tum the SG165 OUTPUT selector switch
to the MPX SIGNAL position.

2. Connect an oscilloscope to the ALL SIG-
NALS OUTPUT jack, and set the MICROVOLT
output controls to maximum.

3. Turn the LEFT 400Hz on, the RIGHT 400
Hz off, and set the 19KHz pilot to zero.

4, Adjust R250 the MPX balance adjustment
on the MPX board for a straight base line.

10.7MHz IF
FREQUENCY*

1. Set the OUTPUT selector switch to 10.7
MHz IF and turn the AM/FM IF ROCKER con-
trol to the center detent. Switch the LEFT and
RIGHT 400Hz off, and set the PILOT 19KHz
to zero.

C303
)
10.7 AM {RF Freq

Freq, R306

AM RF Lev

R392

FM Mod Lev
R389

N
\
N
N
N
N
N
.
N
N
.
N
N
N
:
A
N

Fig. 55 SG165 Output Calibration Adjustments

2. Connect an accurate DC voltmeter to the 2. Connect a frequency counter or an oscillo-
positive lead of C303, and adjust R306 for 6 scope with a calibrated time base to the jumper
volts DC with respect to chassis. wire on .the main RF board near TR305, and

adjust L305 for an indication of 100KHz.
3. Connect a frequency counter to the ALL
SIGNALS OUTPUT jack and set the MICRO-
VOLT OUTPUT controls for maximum. (A
broad band instrument amplifier will be neces-
sary if the counter does not trigger reliably with 10.7MHz SWEEP PHASE

the 100mV signal available from the SG165).
1. Connect the vertical input of an oscillo-

4. Adjust L301 for exactly 10.7MHz as mea- scope to pin 3 of the main RF board (blanking
sured on the frequency counter. input), and the horizontal input to pin 2 of the
RF board (60Hz sweep). Adjust the scope to
LEVEL* display a lissajous pattern between the vertical
and horizontal inputs. NOTE: The VECTOR
1. Remove the frequency counter from the input of the Sencore PS163 is ideal for this
ALL SIGNALS OUTPUT, and connect an accur- application. If some other scope is used, be
ate RF volt meter. sure tee check it for zero phase shift to the 60Hz
signal.
2. Adjust R391 for 100mV RMS as measured
on the RF volt meter. 2. Adjust R103 on the POWER SUPPLY
board to obtain a circular pattern on the scope,
10.7MHz SWEEP AND MARKERS indicating a 90 degree phase shift between pins

2 and 3. (Refer to Fig. 54)
MARKER FREQUENCY

1. Set the OUTPUT selector switch to the
10.7MHz SWEEP AND MARKERS position.

AM RF
FREQUENCY

1. Tune a good quality AM receiver to a
station with a known frequency near the lower
edge of the band.

2. Set theSG165 OUTPUT selector to AM RF,
the MICROVOLT OUTPUT controls to maxi-
mum, and the AM modulation switch to 30%.

3. Loosely couple the output of the SG165
to the receivers antenna by laying the open
leads of the 39G43 pad near the antenna.

4, Set the SG165 RF tuning to the frequency
of the station tuned in step 1, and adjust L302
and AM RF oscillator slug that the signal from
the SG165 “zero beats” with the station signal.

5. Tune the receiver to a station with a known
frequency near the high end of the band, and
set the SG165 RF tuning to the frequency of
that station.

6. Adjust C305A the trimmer across the AM
section of the tuning capacitor so that the signal
from the SG165 “zero beats” with the station
signal.

7. Repeat steps 1 - until the SG165 tunes
properly at the low and high end of the AM
band.

LEVEL*

1. Connect an accurate RF voltmeter to the
ALL SIGNALS OUTPUT jack.

2. Adjust R392 for 100mV as measured on
the RF volt meter.

455KHz
FREQUENCY*
1.

Set the SG165 OUTPUT selector switch to
the 455KHz IF position, slide the AM MODU-
LATION switch to zero, and set the MICRO-
VOLT OUTPUT controls for maximum output
and center the ROCKER in the detent.

2. Connect a frequency counter to the ALL
SIGNALS OUTPUT jack, and adjust L303 the
455KHz oscillator coil for an output frequency
of 455KHz (a broad band instrument amplifier
will be necessary if the counter does not trigger
reliably on the 100mV output of the SG165).

262.5KHz FREQUENCY*

Follow the same procedure as for 455KHz,
except turn OUTPUT selector switch to 262KHz
IF position, and adjust L304 for an output
frequency of 262.5KHz.

FM RF
FREQUENCY

NOTE: For accurate results these adjustments should
be performed with all shields in place.

1. Connect a good antenna to a good quality FM
receiver, and with the receivers AFC off, tune a
station with a known frequency near the high end of
the band.

2. Remove the antenna from the receiver, and with-
out changing the receivers tuning connect the SG165
to the antenna terminals of the receiver. Set the
SG165 RF tuning to the frequency of the station
tuned in step 1, and the OUTPUT selector switch to
FM RF.

3. Adjust C341A the trimmer across the FM section
of the tuning capacitor so that the output frequency
is exactly the same as the station tuned in step 1.

4. Disconnect the SG165 from the receivers ante-
nna terminals and reconnect the antenna. Tune the
receiver to a station. with a known frequency near the
low end of the band.

5. Disconnect the antenna, and without changing
the receivers tuning connect the SG165 to the ante-
nna terminals. Set the SG165 RF TUNING to the
same frequency as the station tuned in step 4.

6. Adjust L308 and FM oscillator coil so that the
SG165 output frequency is exactly the same as the
station tuned in step 4.

7. Repeat steps 1 -6 until the SG165 tunes accurat-
ely at the low and high end of the FM band.

LEVEL*

1. Set the MICROVOLT OUTPUT controls to
maximum, and connect an RF voltmeter with 10mV
sensitivity to the ALL SIGNALS OUTPUT jack.

2. Adjust R360 for an indication of 10mV on the
RF volt meter.

MODULATION PERCENTAGE*

1. Set the RF TUNING to 98MHz, and connect a
calibrated FM deviation meter to the ALL SIGNALS
OUTPUT.

2. Switch the LEFT and RIGHT 400Hz on, the
PILOT 19KHz to Zero, and the FM MODULATION
switch to IHF MPX.

3. Adjust R389 for 100% modulation (75KHz
deviation).

CIRCUIT DESCRIPTION
BLOCK DIAGRAM

The circuit description of the SG165 is divided into
two sections. The first section refers to the block

diagram in Fig. 56, and is broken down by output.

to show how the blocks are interrelated to produce a
given output. The second section is a transistor by
transistor explanation of the operation of each block.

OUTPUTS USING BLOCK DIAGRAM

67KHz - The 67KHz oscillator TR312 output is selec-
ted by position 1 of SW301E, and coupled to the
output buffer (TR316 - TR321). The buffer output
provides current amplification to the 67KHz signal
and couples it to the MICROVOLT OUTPUT con-
trols and ALL SIGNALS OUTPUT jack through ter-
minal 14 on the main RF board.

MPX SIGNAL - The composite stereo signal generated
by the MPX board is coupled from the output of the
MPX board (pin 5) into pin 1 of the main RF board.
Position 2 of SW301E selects the composite stereo
signal and couples it to the output buffer, where it is
current amplified and connected to the MICROVOLT
OUTPUT controls and the ALL SIGNALS OUTPUT
through pin 14 of the main RF board.

10.7MHz SWEEP AND MARKERS - The 10.7MHz
sweep is generated in the main oscillator (TR301 -
304), switched to operate at 10.7MHz. 60Hz sweep
voltage for the variable capacity diode in the main
oscillator is provided by a 60Hz sine wave that ori-
ginates at pins 4 and 5 of the power supply board,
and is coupled into the main oscillator through pins
2 and 3 of the main RF board. Control of the sweep
center frequency is provided by the ROCKER con-
trol. The sweep output of the main oscillator is
coupled through the isolation buffer (TR308 - 311),
position 3 of SW301E, and the output buffer to pin

14 of the main RF board. From pin 14, the signal is
coupled to the MICROVOLT OUTPUT controls and
then to the ALL SIGNALS OUTPUT.

Markers are generated by first modulating the 10.7
MHz CW signal from TR313 with the 100KHz signal
generated in TR305. The output of modulator TR303
(a 10.7MHz signal with 100KHz side bands) is then
coupled along with a sample of the 10.7MHz sweep
taken from the output of the isolation buffer to the
input of the birdy amplifier TR306 and 307. The
amplified markers from the birdy amplifier are cou-
pled through pin 6 of the main RF board to the
MARKER HEIGHT control. Retrace blanking (pro-
vides a clean base line) is provided by TR1. The 60
Hz blanking signal coupled to the base of TR1 effec-
tively shorts the TO SCOPE jack to ground during the
retract time.

10.7MHz XTAL CONTROLLED - The output of the
10.7MHz crystal oscillator (TR313) is selected by
position 4 of SW301E. The output of SW301E is
amplified by the output buffer, and coupled through
pin 14 of the main RF board to the MICROVOLT
OUTPUT controls and then to the ALL SIGNALS
OUTPUT.

10.7MHz IF - The 10.7MHz IF signal is generated in
the main oscillator (TR301 - 304) switched to operate
at 10.7MHz, with fine frequency adjustment provided
by the ROCKER control. The main oscillator is
frequency modulated by the composite stereo signal
that enters the main RF board through pin 1. The
output of the mian oscillator is current amplified by
the isolation buffer, and coupled through position 5
of SW301E to the output buffer. The current ampli-
fied signal from the output buffer is coupled through
pin 14 of the main RF board to the MICROVOLT
OUTPUT controls and then to the ALL SIGNALS
OUTPUT.

FM RF - The FM RF signal is generated in the FM RF
oscillator (TR314 - 315) and coupled directly to pin
14 of the main RF board and then through the
MICROVOLT OUTPUT controls to the ALL SIG-
NALS OUTPUT. The FM RF oscillator is frequency
modulated by the composite stereo signal that enters
the main RF board through pin 1.

AM RF - The AM RF signal is generated in the main
oscillator (TR301 - 304) switched to operate over
the AM broadcast band. Amplitude modulation is
provided by the 400Hz signal entering the main RF
board through pin 12. The output of the main oscil-
lator is current amplified by the isolation buffer, and
coupled through position 7 of SW301E to the output

buffer. The current amplified signal from the output
buffer is coupled through pin 14 of the main RF board
to the MICROVOLT OUTPUT controls and then to
the ALL SIGNALS OUTPUT.

455KHz and 262KHz IF - The operation for the AM
IF frequencies is the same as for the AM RF except
that the main oscillator is switched to operate at
455KHz or 262KHz, and fine frequency adjustment
is provided by the ROCKER control.

400Hz SINE AND SQUARE WAVE - The sine and
square wave outputs of the 400Hz oscillator board are
coupled to the input of the output buffer through
positions 10 and 11 respectively of SW301E. The
current amplified signal from the output buffer is
coupled through pin 14 of the main RF board to the
MICROVOLT OUTPUT controls, and then to the
ALL SIGNALS OUTPUT.

EXTRA CRYSTAL - The EXTRA CRYSTAL func-
tion operates exactly the same as the 10.7MHz XTAL
CONTROLLED, except that TR318 oscillates at a
frequency determined by the crystal, (not supplied)
inserted in the extra crystal socket.

24k

TR303

Gs R334
TO B5
®7 — swa01a 108
@6 €303
60Hz o5 aut
BLANKING 94 R335
3 100K
O—#;
@ 6! =

TO BLANKER

“)

Fig. 56

CIRCUIT DESCRIPTION
CIRCUIT OPERATION

MAIN OSCILLATOR 10.7MHz SWEEP, 10.7MHz IF,
AM RF AND AM IF

GENERAL

The main oscillator comprised of TR301 and TR302
is used to generate the 10.7MHz swept signal, the
10.7MHz frequency modulated IF signal, the AM RF
signal, and the AM IF signals. Feed back to sustain
oscillation is provided by cross-coupling capacitor
C308. TR303 effectively shorts the collector of
TR302 to ground during retrace in the 10.7MHz
SWEEP & MARKERS function, producing zero out-
put from the main oscillator during retrace. TR304
provides amplitude modulation for the AM outputs
by varying the emitter current to the main oscillator
transistors. The output of the main oscillator is
coupled from the base of TR301 through C357 to the
input of the isolation buffer.

+12 TO TR315
MAIN OSCILLATOR FM RF OSC.

+12
/ $W301C

R319 BLANKING
10k

R312
100

R311 INPUT TO

100K WIPER
357 TR301 = SWS01A
150 R313 =

3.9K a =

TO ISOLATION
BUFFER

SW301D

400H2 SINE

R318 10

10.7MHz IF, AM RF, and AM IF + a1

10.7MHz SWEEP AND MARKERS

For the 10.7MHz Sweep output the resonant circuit
comprised of L301 and varicap diode CR301 is con-
nected to the base of TR301 by position 3 of SW301A
causing TR301 and TR302 to oscillate at 10.7MHz.
The resonant frequency of L301 and CR301 is varied
(swept) by the change in capacity of CR301 caused
by the 60Hz sine wave coupled to it through the
series path of terminal 2 of the main RF board,
position 3 of SW301B, R303 in parallel with C301
C302, and R307. The DC bias, and therefore the
steady state capacity of CR301, is controlled by a vol-
tage divider comprised of R306, R19 (front panel
ROCKER control), and R304. R306 is factory adjus-
ted for positive 5 volts bias, with R19 in its center
detent. R19 varies the bias voltage, providing front
panel adjustment of the 10.7MHz sweep center fre-
quency.

A 60Hz blanking signal to turn off the oscillator
during the retrace of the 10.7MHz sweep is coupled
through pin 3 on the main RF board position 3 of
of SW301A to the base of TR303. When the signal
at the base of TR303 goes positive, TR303 turns on
effectively shorting the collector of TR302 to ground
and killing the oscillator.

The emitter current for TR301 and TR302 flows
from the minus 12 volt supply through R391, R314,
R318 and position 3 of SW301D. R391 is a cali-
bration adjustment adjusted for 100mV output at
the ALL SIGNALS OUTPUT with the OUTPUT
selector in the 10.7MHz IF position.

The 10.7MHz IF function uses the same oscillator
circuitry as the 10.7MHz sweep. The only differences
are that the blanking signal is not applied to the base
of TR303, and a composite stereo signal is applied to
CR301 in place of 60Hz sweep voltage.

AM RF

For the AM RF output, the resonant circuit compri-
sed of L302, C305, and C305A is connected to the
base of TR301 by position 7 of SW301A, TR301 and
302 oscillate at an AM RF frequency as determined
by the setting of the front panel RF TUNING control
C305. C305A (a trimmer mounted on C305) is a
calibration adjustment adjusted for the correct output
frequency at the high end of the AM RF band. L302
is a calibration adjustment adjusted for the correct
output frequency at the low end of the AM RF band.
The 400Hz modulating signal switched by a switch on
_ the MPX board and coupled into the main RF board
through pin 12 varies the base voltage on TR304.
TR304 actually functions as a variable constant cur-
rent source whose output current is varied by the
400Hz modulation signal at its base. The modulated

(FOLD OUT FOR BLOCK DIAGRAM)

output of the constant current source provides the
emitter current for the oscillator transistors, resul-
ting in a 80% amplitude modulated output from the
oscillator. R392 is a calibration adjustment adjusted
for 100mV at the ALL SIGNALS OUTPUT in the
AM RF function.

455KHz If

For the 455KHz IF output, the resonant circuit com-
prised of L303 and C306 is connected to the base of
TR301 by position 8 of SW301A, causing TR301 and
TR302 to oscillate at 455KHz. TR304 provides mod-
ulation the same as it did for the AM RF output.

262KHz IF

For the 262KHz IF output, the resonant circuit com-
prised of L304 and C307 is connected to the base of
TR301 by position 9 of SW301A, causing TR301 and
TR302 to oscillate at 262KHz. TR304 provides
modulation the same as it did for the AM RF output.

ISOLATION AND OUTPUT BUFFERS

The isolation buffer (TR308 - TR310) and the output
buffer (TR316 - TR321) are nearly identical high
gain current amplifiers. The isolation buffer amplifies
the signals from the main oscillator, and provides a
low impedance drive for the output selector switch
SW301E. The output buffer amplifies the signal
selected by SW301E (all except FM RF), and pro-
vides a low impedance drive for the MICROVOLT
OUTPUT controls and ALL SIGNALS OUTPUT.

The input FET (TR308 or TR316) provides the ini-
tial impedance change from a high impedance voltage
sensing input that does not load the preceeding cir-
cuit to a low impedance voltage source to drive the
following circuitry. TR3810 in the isolation buffer
and TR318 in the output buffer operate in conjunc-
tion with TR308 and TR316 as modified darlington
pairs.

If the drain current in TR308 or TR316 tends to in-
crease in drive at the gate, the increased voltage drop
across R343 and R370 will cause TR310 and TR318
to conduct more heavily. The increased collector

' current through TR310 and TR318 will act to make

the source voltage of TR308 and TR316 more posi-
tive which in turn will lower the gain of the two FET
stages. The overall effects then of the compound
connection are to provide an FET source follower of
extremely high Gm and low output impedance.

The only differences between the buffers are: the
output buffer uses larger coupling capacitors to pass
the lower audio frequencies, and the output buffer

MAIN RF

COMP, MPX

MAIN
OSCILLATOR

ALL SIGNALS
OUTPUT

60Hz Sweep
to 2&3
MAIN RF

PWR SUP

+ 12V To <i ON MAIN RF, SWITCHED BY SW 30IF TO & ON MAIN RF TO & ON MPX

CIRCUIT GROUND

LEFT
SPEAKER
LEADS

Fig. 56 Block Diagram for SG165

OUTPUT OUTPUT
METER METER

R343 C327
470 ie To
ee) TR3IO
iN NN. /2N5227
°t—} TR308
R337
eae SWEEP
IM TO
R338 1 C326 MARKER
10 Ol ADDER
O ; 10.7MHz
= -2 = and

EXTRA CRYSTAL

Fig. 57 Isolation and Output Buffers

contains two additional transistors (TR320 and TR
321.) These two transistors function as zener diodes
to protect the output buffer from excessive voltages
applied to the ALL SIGNALS OUTPUT.

67KHz OSCILLATOR

The 67KHz oscillator (TR312) operates only in the
SCA 67KHz function, when plus 12 volts is switched
to the drain of the FET by position 1 of SW301F.

+12 +12
TO TR313 TO TR306, 307

L307
67KHz ADJ.

Fig.58 67KHz Oscillator

The output of the 67KHz oscillator is taken from the
source of TR312, and coupled directly to position 1
of the output selector SW301E. L307 is a calibration
adjustment adjusted for an output frequency of
67KHz.

The 67KHz oscillator current also contains the plus 12
volt switching for the MPX board, the 10.7MHz/EX-
TRA CRYSTAL oscillator, and the birdy amplifier.
In position 3 of SW301F, plus 12 volts is switched to
the birdy amplifier transistors TR306 and TR307 and
100KHz oscillator TR305. This plus 12 volts is also
coupled by CR304 to the 10.7MHz oscillator TR313.
In position 3, 4, and 12 of SW301F, plus 12 volts is
switched to TR313, producing the 10.7MHz marker
the 10.7MHz CRYSTAL CONTROLLED, and the
EXTRA CRYSTAL functions. CR304 blocks the
plus 12 volts from the birdy amp. In positions 2, 5,
and 6 of SW301F, plus 12 volts is switched to the
MPX board, producing a MPX signal for the MPX
SIGNAL, the 10.7MHz IF, and the FM RF functions.

10.7MHz/EXTRA CRYSTAL OSCILLATOR

This oscillator, comprised of TR313 and TR322 con-
nected as a modified darlington pair as outlined in
the ISOLATION BUFFER, operates only in the
10.7MHz. SWEEP AND MARKERS, the 10.7MHz
XTAL CONTROLLED, and the EXTRA CRYSTAL
function when plus 12 volts is switched to the drain of
the FET by positions 3, 4, and 12 of SW301F.

In the 10.7MHz XTAL CONTROLLED and EXTRA
CRYSTAL functions, one wiper of SW301G selects
the crystal, and the other wiper connects the output
taken from the high side of the crystal, to a capaci-
tive voltage divider comprised of C331 and C330. The
junction of C331 and C330 is the output of the
oscillator for the 10.7MHz and EXTRA CRYSTAL
functions, and is connected to positions 4 and 12 of
output selector switch SW30LE.

eae
10
e

Fig. 59 10.7MHz - Extra Crystal Oscillator

In the 10.7MHz SWEEP & MARKERS function, one
wiper of SW301G selects the 10.7MHz crystal, and
the other connects a 10pF capacitor in parallel with
the crystal. This 10pF closely approximates the
capacity across the crystal in the 10.7MHz XTAL
CONTROLLED function. The output of the oscil-
lator for the 10.7MHz SWEEP & MARKERS function
is taken from the source of the transistor, and coupled
through C317 to the 100KHz modulator (CR303).

MARKER GENERATOR

During the 10.7MHz SWEEP & MARKERS function,
plus 12 volts is switched to TR305 - TR307 by
position 3 of SW301F. TR305 oscillates at 1OOKHz,
with L305 a calibration adjustment adjusted for a
100KHz output frequency. The 100KHz output of
TR305 is coupled through C315 and R322 to the
modulator diode CR303. The 10.7MHz crystal signal
is also coupled to the input of the modulator diode

TO POS. 3 of
SW301F

R323 R328
= 100K 6.8K

A om “R327
S :
Kb C315 aap cR303. «C318 R326 ("
313 Ch

100KHz 6200 470 1.2K .001 220

c314 R324 L306 319 R320
27

O -12 47 SWEEP
SAMPLE

through C317 and R325. The output of this modula-
tor actually a 10.7MHz carrier with sidebands 100KHz
above and below (10.6 and 10.8MHz), is coupled
through C318 and R326 to the input of the birdy
amplifier. Also coupled into the input of the birdy
amplifier is a sample of the 10.7MHz sweep signal
taken from the output of the isolation buffer. At the
base of TR306 (input of birdy amplifier) the 10.6,
10.7, and 10.8MHz signals (markers) from the modula-
tor mix with the 10.7MHz sweep signal. As the
frequency of the sweep signal approaches each of the
marked frequencies in turn, an audio difference fre-
quency is generated. This audio difference frequency
is amplified by TR306 and TR307 and added to the
response curve at the TO SCOPE jack to produce the
‘“‘birdy”’ post injection markers.

FM RF OSCILLATOR

The FM RF oscillator transistor TR314 runs only in
position 6 of SW301C when plus 12 volts is connected
to the base of TR315, turning TR315 on, and supply-
ing emitter current to TR314. R360 is a calibration
adjustment that controls the emitter current of TR
314, and therefore the output level of the FM RF
oscillator. The effective resonant circuit for the
FM RF oscillator is L308 and the parallel combina-
tion of C841, C341A, and varicap diode CR307.
C341 is a tuning capacitor connected to the RF
TUNING control, and varies the frequency of the
FM RF oscillator from 86 to 110MHz. L307 is a
calibration adjustment adjusted for the correct output
frequency at 88MHz, and C341A is a calibration ad-
justment adjusted for the correct output frequency
at 108MHz. CR307 changes capacity in proportion
to the composite stereo signal applied to it, resulting
in the desired frequency modulation. The level of the
composite signal applied to CR307 is controlled by

R332
6.8K

R333 =
27

To
DETECTOR

R18
22K

60Hz
BLANKING
SIGNAL

Fig.60 Marker Generator

+12 FM RF OSC.

R353 C338 R357

5.6K 01 3.3K
C339 10uf R358

R354 1. ——
12k = = Ta314 |e pe
R356 33K =—C340

6
10 c341 | 03414 342 \
7+
us

7,
L308 I
i 68
CR307 LL 72k

R355
12K

R351 C337 “ 50K
15K 100 C344 R361

TO COMPOSITE
MPX SIGNAL
PINT MAIN RF
BOARD

Fig.61 FM RF Oscillator

R387 and R389. R389 is a calibration adjustment
adjusted for the correct percentage of modulation.
R387 is connected to the RF TUNING control, and
adjusts the level of the composite signal to maintain
a constant ratio between the capacity change of CR
307 and the changing value of C341, resulting in a
constant modulation percentage across the FM F™
band.

AUDIO OSCILLATOR

IC301 and IC302 form a function generator with
simultaneous triangle and square wave outputs. When
power is first applied current enters the positive
(noninverting) input of IC301. This positive input is
amplified by IC301, and coupled back to its input by
positive feedback resistors R375 and R376. This
feedback causes the output of IC301 to go maximum
positive almost instantaneously. The output of IC301
is coupled to the negative (inverting) input of IC302
by R380. IC302 functions as an integrator, charging
C352 with a linear negative going ramp. This nega-
tive ramp is coupled back to the input of IC301 by
R377. When the negative signal coupled to the input
of IC301 reaches a high enough value to overcome
the positive feedback, the input of IC301 starts to go
negative. This negative going signal is amplified by
IC301, and coupled back to the input through R375
and R376, causing the output of IC301 to go to max-

TR324
MPS5172

CR311 CR310 CR309
IN4148 IN4148 IN4148

TO SW30TE
POS 11

C356 TO MPX

2ut TO SW301E BOARD
12 POS. 10

Fig.62 Audio Oscillator

imum negative almost instantly. This negative signal
is coupled to the input of IC302, causing IC302 to
charge C352 with a linear positive going ramp. When
the amplitude of this positive ramp coupled back to
the input of IC302 reaches a high enough value to
overcome the negative signal from its output, IC301
again switches to a positive output, completing one
cycle of oscillation.

The square wave from the output of IC301 is taken
from the junction of R378 and R379, and coupled to
position 11 of SW301E for the 400Hz SQUARE
WAVE output.

The triangular wave (positive and negative going
ramps) is coupled from the output of IC302 to the
active filter comprised of TR324 and TR323. The
output of the filter (400Hz sine wave) is coupled to
the input of the MPX board through pin 15 on the
main RF board and pin 4 on the MPX board. The
400Hz sine wave is also coupled to position 10 of
SW301E for the 400Hz SINE WAVE output. CR309
- 311 are used to insure that the DC component of the
sine wave output will be slightly negative insuring
the proper polarity voltage on C220 and C221 on the
input of the MPX board.

R375 is a calibration adjustment that controls the
amount of feedback from the output of IC301 to its
input, and therefore the level of the ramp on the
output of IC301 necessary to cause IC3801 to change
states. In practice, this control is adjusted for a one
volt RMS output in the 400Hz sine wave position.

76KHz OSCILLATOR AND SHAPER

TR201 and its associated circuitry from a crystal
controlled oscillator controlled by the 76KHz crystal
connected from collector to base. The output of this

Lia ihe eet aor i aad

C204

220 TO3BKHz
MULTIVIBRATOR

MPS5172

)
R203
c201 TR201 10K
.001 |

Fig.63 76KHz Oscillator and Shaper

oscillator (a clipped sine wave) is coupled through
C203 to the base of TR202. C2038 and R203 form a
differentiating network so that only the leading and
trailing edges of the sine wave are coupled to the
base of TR202. TR202 has no DC bias voltage applied
to its base, so it will only conduct when it receives a
positive pulse from TR201. The positive pulse is
amplified, and inverted by TR202, producing a 12
volt negative pulse at the collector. This negative
pulse is coupled by C204 to the trigger input of the
38KHz bi-stable multivibrator.

38KHz MULTI-VIBRATOR
\

+12V

FROM 76KHz SHAPER

OUTPUT

R265
5.1K

-12V

Fig.64 38KHz Multi-Vibrator

TR208 - 206 and their associated circuitry function
as a cross coupled bi-stable multi-vibrator that actively
switches plus or minus 12 volts to its outputs. In
normal operation, one pair of cross coupled tran-
sistors (either TR203 and TR206 or TR204 and
TR205) will be on, and the other pair will be off.
When the multi-vibrator receives a negative trigger
pulse at the junction of CR201 and CR202, both

OUTPUT

TO 19KHz

pairs of transistors change states, causing the output
that was positive to switch negative, and the output
that was negative to switch positive.

When power is first applied, one pair of transistors
will turn on, and the other off as a result of the slight
differences in transistors. If TR206 is on, it connects
minus 12 volts to output 2. The minus 12 volts at
output 2 is coupled to the base of TR203, turning it
on, and to the base of TR205, turning it off. With
TR208 on, and TR205 off, plus 12 volts is connected
to output 1. The plus 12 volts at output 1 is coupled
to the base of TR204, turning if off, and the base of
TR206, insuring that it stays on.

A negative trigger pulse at the junction of CR201 and
CR202 would have no effect on TR203 because the
base of TR2083 is already negative. The pulse would
be coupled through CR202 to the base of TR204.
TR204 would amplify and invert the negative pulse,
resulting in a positive pulse at output 2. The positive
pulse at output 2 would be coupled to the base of
TR205, turning it on, and to the base of TR203,
turning it off, resulting in output 1 switching negative.

The negative signal at output 1 would be coupled to
the base of TR206, turning it off, and to the base of
TR204, reinforcing the negative trigger pulse, and
turning TR204 on, resulting in output 2 switching
positive. The next negative trigger pulse would turn
TR203 back on, returning the multi-vibrator to its
original state. In other words it takes two trigger
pulses to cause the multi-vibrator to go through one
complete cycle, resulting in two 38KHz outputs that
alternately switch from plus to minus 12 volts.

STEREO SWITCH

Diodes CR207 - CR214 perform the actual stereo
switching. When output 1 of the 38KHz multivibra-
tor is positive, and output 2 is negative, diodes CR
107 - CR210 (left channel switch) are forward biased,
and couple the left signal to the FM MODULATION
switch. When output 1 is negative, and output 2 is
positive, diodes CR211 - CR214 (right channel switch)
(SW202) and the RIGHT 400Hz switch (SW203)
select the left and right channel signals.

When both the LEFT and RIGHT 400Hz switches
are on, as shown on the main schematic, the 400Hz
sine wave coupled through C220 is connected to both
the left and right channel switching diodes. If one
channel is off, the on channel receives the 400Hz sine
wave from C220. The off channel receives a small
amplitude 400Hz sine wave that is 180 degrees out of
phase with the 400Hz sine wave to the on channel.
This out of phase signal compensates for any 400Hz
that may be coupled to the off channel from the on

TO 400Hz

SINE WAVE

TOMPX CR205
FILTER

Fig. 66

Fig.65 Stereo Switch

19KHz Multivibration and Filter

channel. R250 is a calibration adjustment that con-
trols the amplitude of the out of phase 400Hz, and is
adjusted to exactly cancel any of the in phase 400Hz
that may appear in the off channel. When both the
LEFT and RIGHT 400Hz switches are off, the inputs
of both diode switches are grounded resulting in zero
400Hz on the output of the switches.

19KHz MULTIVIBRATOR AND FILTER

TR207, TR208 and their associated circuitry form a
bistable multi-vibrator that divides the 38KHz input
from the 38KHz multivibrator by 2 resulting in a 19
KHz output. TR209 and TR210 provide active filter-
ing for the 19KHz square wave from the multi-vibrator
producing a 19KHz sine wave that is phase locked to

_ the 38KHz multi-vibrator. The PILOT 19KHz switch

(SW201) selects the level of 19KHz sine wave. In the
“0” position the 19KHz sine wave is connected to
ground. In the 5% position, R238 (33K) is shorted
and R234 (62K) is in series with the 19KHz. In the
10% position, R234 is shorted, and R233 is in series
with the 19KHz.

MPX OUTPUT FILTER

TR212 - 216 form a very linear low pass filter with a
cutout frequency of approximately 60KHz. This
allows the filter to pass the fundamental of the com-
posite stereo signal, but block the switching tran-
sients of the 38KHz switching signal.

The composite stereo signal at the input of the filter
is amplified and inverted by TR212. The signal at
the collector of TR212 is also present at the base of
emitter follower TR213, which couples its base signal
unchanged to its emitter. R254 provides negative
feedback and DC bias to the input of TR212. This
negative feedback fixes the input impedance of TR
212 at 10K.

The two active filters are basically the same, with the
only difference being that the second uses two tran-
sistors connected as a Darlington amplifier to achieve
the required current gain to drive the output. The
cutoff frequency is determined by the values of the
two resistors in series with the base, and the value
of the capacitor from base to ground and from the
emitter to the junction of the resistors in series with
the base. The sharpness of the filter is determined by
the ratio of the values of the two resistors. An under-
standing of how the resistor and capacitor values
effect the filter characteristics can be obtained by
comparing the filter on the 400Hz audio PC board
with the MPX filter. The 400Hz filter operates at a
much lower frequency, therefore the resistor and
capacitor values are larger. The 400Hz filter is also
designed for a sharp frequency cutoff with equal

FROM
MODULATOR
OUTPUT

values_of resistors. The MPX filter with approxi-
mately a 4 to one ratio of resistor values is designed
for a much smoother frequency cutoff. This smoother
cutoff is necessary to prevent any phase shift that
would degrade the separation of the MPX signal.

SPEAKER LOAD AND OUTPUT METERS

The circuitry for the left and right channel is identi-
cal, so for simplicity sake we will only discuss the

FROM
AMPLIFIER OUTPUT

LEFT CHANNEL

Fig.68 Speaker Lodd and Output Meters
operation of the left channel. SW3A selects the
load resistor connected across the input leads. For
the four ohm position of the SPEAKER LOAD
switch, two 8 ohm resistors are paralled, for the 8
ohm position an additional 4 ohm resistor is switched
in series, for the 16 ohm position, an additional 8
ohm resistor is switched in series. In the SPEAKERS
position there is no load other than the meter circuit.

In the 10W and 100W positions of the POWER
RANGE switch SW4A switches the input to the wiper
of SW3B. SW3B is ganged to SW3A, and selects the
correct primary tap on the meter transformer T2

Fig.67 MPX Output Filter

TO RF MODULATORS
R262 AND OUTPUT BUFFERS
OK

to maintain correct wattage calibration for the speaker
load selected. In the SPEAKERS position, the 8
ohm tap is selected. When the POWER RANGE
switch is in the SEPARATION TEST position, SW4A
bypasses SW3B, and connects the input directly to
the 4 ohm tap of T2. This provides maximum meter
sensitivity, and allows the separation scale to be used
for even low power receivers. The meter circuit,
with a sensitivity of 2.1V RMS full scale is switched
to the taps of T2 by SW6B. In the SEPARATION
TEST position, the full secondary voltage is selected,
providing maximum sensitivity. In the 1OW and 100W
position, lower secondary voltages are selected, pro-
viding the necessary range switching.

POWER SUPPLY

The reference for the plus 12 volt output is zener
diode CR105. TR103, the error amplifier for the
positive supply, senses the voltage at the junction of
R110 and R111. If this voltage increases, the current
through TR103 increases, making its collector more
negative. This negative change is coupled to the base
of pass transistor TR101, reducing its forward bias,
increasing its resistance, and bringing the output vol-
tage back down to 12 volts. If the sense voltage
decreases, the current through TR103 decreases, and
its collector becomes more positive. This positive
change is coupled to the base of TR101, increasing
its forward bias, decreasing its resistance, and bring-
ing the output voltage back up to 12 volts. TR102
provides current limiting by sensing the output current
through R107. When the current through R107
reaches 125mA, the voltage drop across R107 is .6
volts. This voltage turns on TR102, removing the
forward bias from TR101.

TR105, the error amplifier for the negative supply,
senses the voltage at the junction of R113 and R114.
The voltage at this point will reflect any change in

either the positive or negative supply. If the negative
output decreases, or if the positive increases, forward
bias on TR105 decreases, causing its collector voltage
to change in a negative direction. This negative
change is coupled to the base of pass transistor TR104
increasing its forward bias, decreasing its resistance,
and maintaining the negative supply voltage equal
and opposite the positive supply. If the negative out-
put increases, or the positive decreases, forward bias
on TR105 will increase, causing its collector voltage
to change in a positive direction. This positive charge
is coupled to the base of the pass transistor, decreasing
its forward bias, increasing its resistance, and again
maintaining the negative supply voltage equal and
opposite the positive supply.

SWEEP OUTPUTS
TO RF SECTION

Outputs 4 and 5 of the power supply provide the
60Hz sine waves for the 10.7MHz SWEEP and MARK-
ERS function. Output 5 is the blanking output that
turns on the sweep when it is negative. Output 4
supplies the voltage that is applied to the varicap
diode to produce the sweep. The phase of output 4
leads output 5 by 90 degrees, so that when the sweep
is on (output 5 negative), output 4 is changing from
maximum negative to maximum positive. R103 isa
calibration adjustment adjusted for exactly 90 degrees
between output 4 and 5.

Fig.69 Power Supply

CONCLUSION:

Check and replace as necessary
line cord, or fuse. If new fuse
opens, disconnect power trans-
former from power supply board.
If fuse still open, replace T1. If
fuse remains good, check power
supply board, especially CR101 -
CR104.

CONCLUSION:

Remove power supply output plug
from side of shielded assembly; if
power supply voltages return to
normal, a short exists in the po-
wer supply distribution system. If
still incorrect troubleshoot power
supply, starting at output of
rectifiers.

Are output signals present at gate of
TR316 (lead of large .47 capacitor)?
Check all output functions. Only
the FM RF is not connected through
this point. Scope probe will load
some outputs, so if any are present
conclusion is yes.

TROUBLE CHARTS

SG165 COMPLETELY DEAD

Check matching pad, and output cable. Check inter-
nal molex connectors for proper installation. Turn
unit on. Does pilot light light?

YES

Check all outputs. If all are dead,
is plus 12 volts present at positive

end of C105, and negative 12 volts
at negative end of C106?

YES

Disconnect main RF board output
phono plug from the PC board

(near the rear of RF tuning control).
Are proper signals present at PC
board output?

YES

CONCLUSION:
Check connecting cables and
attenuator for shorts or opens.

(Cont. on next page)

NO YES

CONCLUSION: Are signals present on output
Make DC voltage checks on main source of TR316?

RF board. Note that some stages

receiver power only when output

selector is turned to that function

NO YES

CONCLUSION: CONCLUSION:
Problem is in TR316 or associated Check all connections in output

components. attenuator and wiring from main
RF P.C, Board.

ES ae EL a NE SE a tS 2 het EE eg Se
STEREO MPX MODULATION MISSING OR INCORRECT

Tum output selector to MPX SIGNAL and connect
scope to ALL SIGNALS OUTPUT, MICROVOLT
OUTPUT CONTROLS to maximum. Switch LEFT
400Hz ON, RIGHT 400Hz OFF, PILOT 19KHz to
10%. Is 2.8V p-p wave form below present at output.
Pay particular attention to 19KHz riding on outside
of 400Hz envelope. NOTE: If 19KHz is missing,
check first at collector of TR208. If multivibrator
is not running suspect TR207 and TR208.

NO YES

Is wave form correct at pin
1 (MPX input) or main RF
board? ll,

CONCLUSION:
‘| Problem is on main RF board,
iui uyenryninyy check for waveform above on
TET TRU THT TTT varicap diodes, with output
selector turned to that output.
Also check DC voltages and
diodes themselves.

f'
HY

ly NW
WY

(Cont. on next page)

Is signal present at output
pin 5 of MPX board?

Is signal present at base of
TR212?

NO
Is 400Hz sine wave present

at junction of CR207 and
209?

NO
CONCLUSION:

Use scope to locate missing
400Hz?

Is 76KHz negative pulse present
at junction of CR201 and 202?

CONCLUSION:
Check and replace as necessary
TR201 or TR202

YES

CONCLUSION:
Check wiring and connections
between MPX input and pin 14

YES

CONCLUSION:

Check wiring and connections
between MPX and main RF
board

YES

CONCLUSION:
Use scope to troubleshoot 60KHz
filter

YES

Is 38KHz square wave (23v p-p)
present at outputs 1 and 2 of
38KHz multivibrator?

CONCLUSION :
Check and replace as necessary
CR207 - CR214

YES

CONCLUSION:

Defect in 38KHz multivibrator.
Check and replace as necessary
TR203 - 206 or CR201 and
202.

TROUBLE
All outputs clipped or distorted

Bad ringing or slow rise to 400Hz
square wave

10.7MHz SWEEP & MARKERS,
10.7MHz IF, AM RF, 455KHz
IF, 262KHz IF outputs missing
or distorted.

No markers at to scope jack
in 10.7 sweep output.

One output only missing

Raa 4
R4 b
R R IR
43] 46 45 |44 Ad “ue
e, aes?
EEG ey ae 2 (Re ea
© cre cril O ae)
Or a)
CRB cRi4 oe fo
O é ie |
J2 76KH
CRIO ae \GerstaL
es
© J5 J7
3 O
lf TR

C}+-6V R63

cra IZ pg =
a al na

R26) —=R27 (8) REI ; ze)
e( |. Jef \a/ b NG
Die y Oe) RCPS

Sie) , | —— +4
é os Wad xX %® xX = R86 C26 C23. 22\ ln
ee (TE x x & x ~~"
<< 5 ee R39 3G Ni) He
R2 = x x C20, + bh R5}
ap R227 a Ray NIB XX XN LAD
Cs WTR ames jO & R48
CPx TR — Ov4
CRS Zoe Vel Ce) SENCORE
ho aT 1 Raz Re ay eS
2 a Gis Rp ( I
tre R32 31 \ AIS

Fig. 70A MPX Board, Component Side

PROCEDURE AND PROBABLE CURE

Follow trouble tree for no outputs. Likely
cause: shorted TR318 - TR321

Check for proper square wave at output of
IC301. Likely cause, defective IC301 (748)

Defect in either main oscillator, or isolation
buffer. If outputs are present at source of
TR308, suspect TR309 - TR3811. If not, sus-
pect TR301 - TR303, and TR308. Make DC
voltage measurements, and check transistors
with an in circuit tester.

Check for 100KHz at source of TR305, if not
there, suspect TR805 or L305. If 100KHz is
present, use scope to troubleshoot birdy amp,
also suspect TR1.

Check oscillator transistor(s), and coil. For
10.7MHz SWEEP, also suspect TR1.

ar | ~
B 3 }
sor ps a
ne ae t ; = ©
he ” 4 x FA neh x Re AL We if.
S ; * /@#G)
ote x oe 63 Jere(4)e
46% e »»v):% @ pe
O/ 55 Se $3CS\\eits @ | |
x > 4 x Ps " DLN h-SEe
di =
pe © XO 83 x } *% rez ay 2
‘ JS Ge r }
PERS $ 8
Bross st : is #6) | ||
——< ANKE ae yh . a
] | SEN > ie. HH
oe AG) Se
‘ ee a — i
tear hse bee | ||) sett
= if x Sag at a8
” FL 3 1 Sup) We 6
6) eee dle AND
eg = o..% 5) Rl | Hag (9) pnd
s] £ x x Mus $ x x x Band Ws
ie) a x KX S/ ends 3
O65 ee AVN a 3 Oo
ay 3 = ae at
$ | Rigs

Fig. 70B Foil Side

Sil

ovY
_ SENCORE
G2 L301
Rol
b
= CR) 3
a (BG
= Xe) RIAA I
i—Cc28
al

#43A48D

xV ao)
EXTRA Si Pe e
CRYSTAL |
SOCKET ae ;
es >
: 3] C30 Sik 7 2 is
=

RBLY G BY:

3 = Ser RBZ RS (

Si , oy: R2 == 33 x a

Rog SS [aes rok
: oe ss P 4BR

Os ee R30 > > 1) a

C22

ie 43A48D

Fig. 71B Foil Side

=|
= VW
>
>—jr\—2 div ake
eS 43859 GZ)
ES Seco coe ee

Fig. 72A Audio.Osc. Board, Component Side Fig. 72B Foil Side

+
C4 @ aR
(6): eo @ # PL
CRS 1) +3 = He
Bigs
. a) \. &
of low 4) 2
SENCORE | 2 nis i “6 ,
z o's

* 43047

Fig. 73A Power Supply Board, Component Side Fig. 73B Foil Side

®@

Ci) @) @) @) @) @®

Fig. 74 Feedthrough Test Points
(Main RF numbers)

13 10 7:12 «19:15
rR BLyosBY

6 BR/W
4R/W
5B

Fig. 75 Main RF Board Connections

SERVICE AND WARRANTY

You have just purchased the only AM-FM Stereo Analyzer on the market today. The Sencore SG165 has been in-
spected and tested twice at the factory and has passed a rugged use test by our Quality Assurance Department to
insure the best quality instrument to you. If something should happen, the SG165 is covered by a standard 90 day
warranty as explained on the warranty policy enclosed with your instrument.

Sencore has six regional offices to serve you. Instruments to be serviced should be retumed to the nearest regio-
nal office by UPS if possible. Parcel post should only be used as a last resort. Instruments should be packed with
the original packing materials or equivalent, and double boxed to insure safe arrival at the regional office. The
blue and white display carton IS NOT an acceptable shipping container. When returning an instrument for service,
be sure to state the nature of the problem to insure faster service.

If you wish to repair your own SG165 AM-FM Stereo Analyzer, we have included a schematic, trouble chart, and
parts list. Any of these parts may be ordered directly from the regional office nearest you.

We reserve the right to examine defective components before an in warranty replacement is issued.

SENCORE REGIONAL OFFICES:

East Central Sales & Service Central West Sales & Service
4105 Duke Street 3200 Sencore Drive

Alexandria, Va. 22304 Sioux Falls, South Dakota 57107
703 751-3556 605 339-0100

Western Coast Sales & Service Northeastern Sales & Service

833 Mahler Road 1593H Central Avenue
Burlingame, California 94010 Albany, New York 12205

415 697-5854 518 869-0996

Central Sales & Service

Southeastern Sales & Service _ 2711 B Curtis St.

2459 Roosevelt Hway Suite B-9 Ellsworth Industrial Park

College Park, Ga. 30337 Downers Grove, Illinois 60515

404 768-0606 312 852-6800

Form 845 Printed in U.S.A.

THE

at less cost than foreign imports!

oe PEO,

ee SENCORE

3200 SENCORE DRIVE, SIOUX FALLS, SOUTH DAKOTA 57107

SCHEMATIC
AND PARTS LIST

$G165
AM-FM
STEREO ANALYZER

<P PEO,
RY <ée
,
2g
3200 SENCORE DRIVE, SIOUX FALLS, SOUTH DAKOTA 57107

REFERENCE

§6165 PARTS LIST

DESCRIPTION

CHASSIS MOUNTED COMPONENTS

C4
CR1
CR2
M1
M2
R10
R11, 12,14
R13
R15
R16
R17
R19
swWwl
Sw2
SW3
Ssw4
T1
T2,3
TR1

Capacitor, variable, Rkr
Diode, 1N4148

Diode, 1N34A

Meter, LEFT OUTPUT
Meter, RIGHT OUTPUT
Control, 75 ohm, L-pad
Resistor, 8 ohm, 5%, 22W
Resistor, 4 ohm, 5%, 22W
Resistor, 16 ohm, 5%, 22W
Resistor, 36K, 1%, 4%W
Control, 200K, Mrk Ht.
Control, 20K, 10%, Rkr
Switch, slide, DPDT
Switch, rotary, 4 section
Switch, speaker load
Switch, power range
Transformer, power
Transformer, 400Hz Audio
Transistor, SE3002

POWER SUPPLY BOARD COMPONENTS

C101, 102
C103, 108
C104, 107
C105, 106
CR101, 102,
103, 104
CR105
R103

R113
TR101
TR102, 103
TR104
TR105, 106

MPX BOARD COMPONENTS

C201
C202
C206
C218
C225, 226,
227, 228

CR201, 202

CR203-206
CR207-214

Power supply board assembly

Capacitor, .22uF, 100V
Capacitor, 1000uF, 25V
Capacitor, 2uF, 15V
Capacitor, 250uF, 15V

Rectifier, 1A, 800 PIV

Diode, 6.2V Zener, 1N1 766A

Control, 25K, Vert, PC Mt.
Control, 5K, Vert, PC Mt.
Transistor, MJE180
Transistor, 2N5172
Transistor, MJE170
Transistor, 2N4248

Multiplex board assembly

Capacitor, .001luf, 5%, 160V
Capacitor, 560pF, 5%, 125V
Capacitor, .luF, 10%, 100V

Capacitor, .0luF, 5%, 33V

Capacitor, 150pF, 5% 125V

Diode, 1N34A

Diode, 1N4148

Diode, 1N4148, (2 matched
quads) price for 4 diodes

PART NO.

24B285
50C5-2
50C3-1
23B45
23B46
15C11-1
14A72-2
14A72-1
14A72-3
14C29-3604
15C1-3
15C3-26
25G3
25A168
25A174
25A181
28B50
28B53
19A7-1

143A47
24G168
24G272
24G133
24G111

16G5
50C2-1
15C7-12
15C7-14
19A29
19A28
19A30
19A14-1

143A46-A
24G188
24G257
24G104
24G183

24G262
50C3-1
50C5-2

50C5-2

PRICE

8.75
29
.25

15.75
15.75

7.25
25
.25
.25
15

1.00

1.25
.50

4.75

2.25

5.75

5.75
.50

R231
R235, 239, 243,
244, 245, 246,
248, 254

R238, 242
R250

R257, 260
R258, 261
Sw201

SWw202, 203
Sw204

SW205

TR201, 202,
205, 206, 209,
210, 212, 213,
214, 215, 216
TR203, 204, 211
TR207, 208
Y201

MAIN RF BOARD AND AUDIO OSC. BOARD COMPONENTS

C301
C305 & 341
C306, 307
C308, 337
C314

C313

C322

C324

C328, 353, 354
C329

C331, 348, 351
C333

C334

C342, 357
C345

C349

C352

CR301, 307
CR302, 304,
305, 309, 310,
311

CR303

1C301

10302

L301

L302, 303
L304

L306

L305, 307
L308

R306, 360, 389
392

R375

R387

R391

SWw301

Resistor, 3.2K, 2% ‘“2W

Resistor, 10K, 1%, “%W
Resistor, 29.4K, 1%, “%W
Control, 2K, Vert., PC mt.
Resistor, 4.7K, 1%, %zW
Resistor, 17.5K, 1%, 42W
Switch, rocker, 2P3P
Switch, rocker, DPDT
Switch, slide, 2PDT
Switch, slide, 4PDT

Transistor, 2N5172
Transistor, 2N4248
Transistor, 2N4274
Crystal, 76KHz

Audio Osc. Board Assembly
RF Board Assembly
Capacitor, 100pF, 5%
Capacitor, variable, RF TUN
Capacitor, 390pF, 5%, 125V
Capacitor, 100pF, 5%, NPO

Capacitor, 2100pF, 5%, 125V

Capacitor, .0062uF, 5%, 33V
Capacitor, .0056uF, 5%, 33V
Capacitor, 150pF, 5%, 125V
Capacitor, .0luF, 5%, 33V
Capacitor, .005uF, 5%, 33V
Capacitor, 6.8pF, 10% NPO
Capacitor, 5pF, 5%, NPO
Capacitor, 20pF, 5%, NPO
Capacitor, 1.5pF, 20%
Capacitor, .47uF, 200V
Capacitor, 2000uF, 25V
Capacitor, .047uF, 5%, 33V
Diode, varicap, BA141

Diode, 1N4148

Diode, 1IN34A

Linear IC, Na. 748

Linear IC, No. 741

Coil, 10.7MHz, Adj

Coil, AM RF, Adj

Coil, 455KHz, 262KHz, Adj
Coil, 5uH

Coil, 100KHz, 67KHz, Adj
Coil, FM RF, Adj

Control, 50K, Vert, PC Mt.
Control, 25K, Vert, PC Mt.
Control, 20K, Mod Tracking
Control, 100K, Vert, PC Mt.
Switch, Output selector

14C30-3203

14C29-1004
14029-2944
15C7-10
14C29-4703
14C29-1754
25G170
25G169
25B171
25B172

19A28
19A14-1
19A18
47G4-1

43A52-A
143A48-A
24G283
24B264
24G105
24G70
24G174
24G261
24G179
24G262
24G183
24G259
24G138
24G153
24G77
24G132
24G146
24G240
24G237
50C11-1

50C5-2
50C3-1
69A2
69A1
46A53
46A54
46A55
46G6
46G11
56A56

15C7-11
15C7-12
15C3-25
15C7-13
25C173

TR301, 302, 303

314, 315 Transistor, SE3002 19A7-1 .50
TR304, 306, 307
320, 321, 323,
324 Transistor, 2N5172 19A28 .50
TR305, 308,
312, 313. 316 FET, MPF102 19A19 15
TR310, 318, 322 Transistor, 2N5227 19A16-1 .50
Y301 Crystal, 10.7MHz 47A18 4,00
MISCELLANEOUS
Front panel escutcheon 8B68 .50
RF TUNING dial 8A69 1.00
Dial marker, AM 8A70 .50
Dial marker, FM 8A71 .50
Indicator Lamp and Holder 20A7 50

Knob, speaker load, power
range, microvolt output

rocker 21A37 1.00
4:1 drive, RF TUNING 21A56 2.50
Knob, Output selector 21G52 2.25
Knob, RF TUNING 21G53 2.25
Line cord 27G12 1.25
75/300 ohm matching pad 39G43 15.50
and cable

Scope vertical lead 39G44 _ 2.00
Detector probe 39G45 4.00
Auto radio dummy antenna 39G53 2.00
Fuse holder 64G28 1.00
Case wrap assembly 110C275 22.75

Prices in effect at date of printing and are subject to change without notice.

When ordering parts, please specify model number, part number and description. Service and parts invoices
are C.0.D. Please include remittance (check or money order) with your order to save C.O.D. charges.
Minimum billing $3.00.

FORM 846 Printed in U.S. A.

ENJ OY YOUR BOOKS 7

PLEASE VISIT OUR STORE FOR EVEN MORE GREAT
STUFF!

WWW.EVERYTHING4LESSSTORE.COM
COPYRIGHT NOTICE

THANKS AGAIN AND PLEASE TAKE THE TIME TO
VISIT OUR STORE.

ATTENTION! EVERYTHING ON SALE NOW!!

seman
cul

HOT SALE!

THIS PAGE COPYRIGHT VON WALTHOUR PRODUCTIONS
WWW.EVERYTHING4LESSSTORE.COM

Related across Profoundd

Oregon Climate Docs

Ashland — Climate and Energy Action Plan (CEAP) p.97
The Role of the Community Here are some actions that everyday Ashland residents and organizations can take to make a difference in addressing climate change. Assemble an emergency kit . Jackson County offers tips and …
Medford — Climate-Friendly Areas Evaluation Report p.39
2 • A mixture of event types and the opportunity for continuous feedback allows for more successful use of information. • Visually appealing and easy -to-read project information ensures the intended message is por…
Medford — Climate-Friendly Areas Evaluation Report p.43
2 • A mixture of event types and the opportunity for continuous feedback allows for more successful use of information. • Visually appealing and easy -to-read project information ensures the intended message is por…

WEF Publications

Transforming Small Businesses 2025 p.17
We are ready to experiment – but the OEMs are reluctant We have identified the way in which AI can help us. But our customers, that is, the OEMs, do not want to experiment with a process that has been working well …
Investing in Water Aligning Investment Strategies with Water Innovation 2025 p.4
Whether it is safeguarding the natural beauty of our freshwater ecosystems, solving water scarcity, providing affordable sanitation to all, delivering safe, contaminant-free drinking water or powering the industries …
Future Proofing the Longevity Economy 2025 p.37
By 2050, the longevity economy will be shaped by evolving demographics, technological advances and shifting societal priorities. To explore what longer, healthier lives could mean for work, finance, healthcare and inte…

Epstein Files

EFTA01222443 — P3PC-4272-01EN
P3PC-4272-01EN FUJITSU Image Scanner fi Series Safety Precautions Thank you for purchasing this Color Image Scanner fi Sanas. This document contains the general information for safety that must be read before using this …
EFTA02705326 — OWNER'S MANUAL
OWNER'S MANUAL XD600/1 600W Monoblock Subwoofer Amplifier Nex SWITCHING TICHNOLOGr Thank you for purchasing a IL Audio amplifier for your automotive sound system. Your amplifier has been designed and manufactured to exac…
EFTA00796191 — 750 KVA PAD MOUNTED STEP-I P TRANSFORMER
750 KVA PAD MOUNTED STEP-I P TRANSFORMER PART 1 - GENERAL Ci SADIAPPROV fin 1.1 RELATED DOCUMENTS: APt>1-1OVED AS NOTED A. Drawings and general provisions of the Contract apply to this Section._ r,J:D AND RESUBMIT for Co…

Federal Writers' Project

[Spark, The Mighty Man]
7F7 V44-erwiteArt..... SPARKS, THE MIGHTY MAN January 4, 1921 (My 19th birthday) went to the recruiting station on Bast 23rd St. and wenlisted in the United States Marine Corps, for a period of four years. Tomorrow I go …
[George F. Gaynor]
Forms to be Filled out for Each Interview FORM A Circumstances of Interview STATE New York NAME OF WORKER Swenson ADDRESS 1 9 1939 FOLKLORE NEW YORK DATE June 5, 1939 SUBJECT Folklore of Communications, Marine Radio Oper…
[Yankee Innkeeper]
ORIGINAL MSS. OR FIELD NOTES (Check one) PUB. Living Lore in New England (New Hampshire) TITLE Yankee Innkeeper Robert E. Gould WRITER DATE IDS. PP. 27 CHECKER DATE SOURCES GIVEN Interview COMMENTS Y.H. Federal Writers,…