Document text
NAVELEX 0969-160-9010
OPERATORS INSTRUCTION MANUAL
FOR
FREQUENCY METER/SIGNAL
GENERATOR SYSTEM
MODEL FM-2748/0DM-1
MANUAL NO. 500783-250
NAVELEX 0969-160-9010
OPERATORS INSTRUCTION MANUAL
FOR
FREQUENCY METER /SIGNAL
GENERATOR SYSTEM
MODEL FM-2748/ODM-1
MANUAL NO. 500783-250
Print 8/72 Lib
Reprint 12/72 Lib
MANUAL CHANGES
SEE ADDENDUM(S) AT
REAR OF THIS MANUAL
SINGER
INSTRUMENTATION
ОТНЕ SINGER COMPANY, LOS ANGELES OPERATION
5340 Alla Road, Los Angeles, California 90066
СОМТЕМТ5
SECTION
1 PNTRODUC СО ое
ESE cennera Е O E КОКАИНА Е
1.2 Signal Сепевавот «Function ANA
>
Frequency Meter/Modulation Monitor Function
11 SPECFETCATTONS T Е
JEJEJE CONTROLS AND INDICATORS
LV OPERATING PROCEDURES .
Power Supply Connections (Mainframe) . . . . . .
Start procedure: ©: «WW uia
Signal Generator Function - CW EE Only .
Set-up Procedure. . = e we аласы КРЕ
Manual Frequency Sweep . ws
Erequeney Meter)Punction са А ПА SIL uc u.a
Antenna Set-up. . LIS ЕМ AA ES OM
Direct Connection Set- Lup LET СН LAA NER
Known Transmitter Frequency: Sa о.
Unknown Transmitter Frequency . . .
NP
Ф ошо мн
Preliminary Oscilloscope Set-up (Mainframe/OAM-1)
и SESS SOUS 5 С
Amplitude Modulated Signal Generator
(Mainframe/OAM-1) == EA
internal Modulation 3 СЕ А
ресетпадимосатаса ор” БУУ.
СУДЕ
Preliminary Oscilloscope Set-up (Mainframe/ODM-1)
СОР 5-1 OD
Internally Frequency Modulated Signal Generator
Mein тате хоре.
Narrowband (0-5 kHz) Peak Deviation И
Wideband (5-15 kHz) Peak Deviation... . .
Wideband (15-60 kHz) Peak Deviation . . .
Combined Internal/External (Two Tone) FM Signal
Generator (Mainframe/ODM-1). . "Esc cue ber Lo
WwW NE
КО OO СО
15 Perd Pi ION 1
O OUP омм N н н
& 4 У „У (У | A A A
1 |
(90) SSA
> PPB
|
= Ney (90) (00)
O
心心 心心
~
1
E
ER
SECTION
4.10
Auer:
„15.
4
4
АЭ
4
4
4,15%
NP
4.16
4.16.1
4.162
4.16.3
АРРЕМОТХ А
py
CONTENTS (Cont)
Externally Frequency Modulated Signal Generator
(Mainframe/ODM-l) . . . .
Measurement of Amplitude Modulation (Mainframe/
OAM LD) nee
Audio Test Tone Generation (Mainframe /ОАМ-1)
Measurement of Peak Deviation (Mainframe/ODM-1)
Audio Test Tone Generation (Mainframe/ODM-1)
General Purpose Oscilloscope (Mainframe/OAM-1)
Internal Horizontal Sweep - - -
External Horizontal Sweep - -
X-Y Mode of Operation . .
General Purpose Oscilloscope (Mainframe/ODM-1)
Internal Horizontal Sweep .
External Horizontal Sweep ·
X-Y Mode of Operation ·
TABLES
Specitications ¢ ос ела
Mainframe Controls and Indicators .
OAM-1 Controls and Indicators .
ODM-1 Controls and Indicators
Second Harmonic Information
ILLUSTRATIONS
FIGURE РАСЕ
т FM-2748 (OAM-1 Plugged In) and ODM-1 . . . . . . 1-0
3-1 Во ETONG ео
3-2 ОАМ-1 "Front: Panel. . "V пъб а о LM = 5
3-3 ODMcLt*Pront Panel. чо тв
4-1 Connections for Signal Generator Function . . . 4-3
4-2 Direct Connection, Frequency Measuring Function 4-4
Tad
i
+
|
ї
1-0
Figure 1-1.
NO
FM-2748 (ОАМ-1 Plugged In)
and ODM-1.
07975
SECTION I
INTRODUCTION
1.1 GENERAL
This volume contains operating instructions for Frequency Meter/
Signal Generator (Mainframe), Oscilloscope Amplitude Modulation
Monitor OAM-1, and Oscilloscope Deviation Monitor ODM-1. The monitor
units are plug-in modules for the Mainframe. The Mainframe ассоп-
modates one plug-in module at a time. The Mainframe together with
OAM-1 is designated FM-2748, see Figure 1-1.
Operation of the Mainframe is simple and does not involve calibration
or locking procedures. Any desired frequency is obtained with full
rated accuracy when power is switched on and the frequency controls
are set at the specified value.
1.2 SIGNAL GENERATOR FUNCTION
The ЕМ-2748 generates an RF output that is precise in both frequency
and level. Signals are generated from 50 kHz to 500 MHz without band
switching and are available at a single RF OUTPUT jack. Output
level із “set at any point from 0.7 pV (-111 ара) to 223 mV (0 арп)
by switching the RF OUTPUT level control in 1 db steps and the RF
OUTPUT VERNIER over а 1 db range. Levels from .07 uV (-131 dbm) to
22.3 mV (-20 dbm) can be obtained by connecting a single RFA-20
attenuator to the RF OUTPUT.
The output is amplitude or frequency modulated using the two modula-
tion plug-in modules. The output can be manually swept over any
1 MHz band within the total frequency range. Precise audio tones
are generated and available at a front panel jack.
Stability and resolution of the FM-2748 make it ideal for testing
narrow-band receivers or checking the responses of Crystal filters,
crystal discriminators, or other narrow-band devices.
1.3 FREQUENCY METER/MODULATION MONITOR FUNCTION
Signals being investigated are applied to detection eireuitryv.viatche
MEASURE INPUT connector by cable or by the plug-in antenna. Locating
the exact position of an unknown frequency in the spectrum is greatly
simplified by means of an interpolating oscillator. This oscillator
provides continuous sweeps over bandwidths of 1 MHZ, 100 kHz, or
10 kHz, with one turn of the 0-1 kHz control. The operator initiates
a search with sweeps over 1 MHz bands. The procedure is repeated
with successive search-bands of 100 kHz and 10 kHz. When the inter-
nal frequency is finally balanced against the unknown frequency with
all seven frequency controls in the circuit, the value of the unknown
frequency is read from the seven dials.
The FM-2748 uses both a light and a built-in speaker to present the
beat note. An audio output jack supplies the beat note to a remote
speaker when necessary. A 45-ohm speaker is recommended for proper
impedance matching. Modulation of the input signal is measured and
displayed on the appropriate modulation plug-in. The recovered audio
is supplied to the speaker system and is available at the front panel
at a level suitable for distortion analysis.
SECTION I
INTRODUCTION
1.1 GENERAL
This volume contains operating instructions for Frequency Meter/
Signal Generator (Mainframe), Oscilloscope Amplitude Modulation
Monitor OAM-1, and Oscilloscope Deviation Monitor ODM-1. The monitor
units are plug-in modules for the Mainframe. The Mainframe accom-
modates one plug-in module at a time. The Mainframe together with
ОАМ-1 is designated FM-2748, see Figure 1-1.
Operation of the Mainframe is simple and does not involve calibration
or locking procedures. Any desired frequency is obtained with full
rated accuracy when power is switched on and the frequency controls
are set at the specified value.
1.2 SIGNAL GENERATOR FUNCTION
The FM-2748 generates an RF output that is precise in both frequency
and level. Signals are generated from 50 kHz to 500 MHz without band
switching and are available at a single RF OUTPUT jack. Output
level is set at any point from 0.7 uV (-111 dbm) to 223 mV (0 арм)
by switchingsthe RF OUTPUT level control in l db steps and the RF
OUTPUT VERNIER over а 1 db range. Levels from .07 yV (-131 dbm) to
22.3 mV (-20 dbm) can be obtained by connecting a single RFA-20
attenuator to the RF OUTPUT.
The output is amplitude or frequency modulated using the two modula-
tion plug-in modules. The output can be manually swept over any
1 MHz band within the total frequency range. Precise audio tones
are generated and available at a front panel jack.
Stability and resolution of the FM-2748 make it ideal for testing
narrow-band receivers or checking the responses of crystal filters,
crystal discriminators, or other narrow-band devices.
1.3 FREQUENCY METER/MODULATION MONITOR FUNCTION
Signals being investigated are applied to detection circuitry vda the
MEASURE INPUT connector by cable or by the plug-in antenna. Locating
the exact position of an unknown frequency in the spectrum is greatly
simplified by means of an interpolating oscillator. This oscillator
provides continuous sweeps over bandwidths of 1 MHz, 100 kHz, or
10 kHz, with one turn of the 0-1 kHz control. The operator initiates
a search with sweeps over 1 MHz bands. The procedure is repeated
with successive search-bands of 100 kHz and 10 kHz. When the inter-
nal frequency is finally balanced against the unknown frequency with
all seven frequency controls in the circuit, the value of the unknown
frequency is read from the seven dials.
The FM-2748 uses both a light and a built-in speaker to present the
beat note. An audio output jack supplies the beat note to a remote
speaker when necessary. A 45-ohm speaker is recommended for proper
impedance matching. Modulation of the input signal is measured and
displayed on the appropriate modulation plug-in. The recovered audio
is supplied to the speaker system and is available at the front panel
at a level suitable for distortion analysis.
SECTION II
SPECIFICATIONS
Specifications for the equipment are defined in Table 2-1.
TABLE 2=1. . SPECIFICATIONS
GENERATOR FUNCTION
Frequency range 50 kHz to 500 MHz leveled and
calibrated from RF OUTPUT
ОО НО tO 5 KHZ Out to speaker
and phone jack
500 MHz to 1 GHz harmonics
uncalibrated at RF OUTPUT
Frequency resolution
Synthesized mode: ен
Variable decade: ТОНЕ 41/2 ‘division
Frequency accuracy (ос to +50°C) (instant on)
Synthesized mode: x TOS
variable decade: 1x пот? +50 Hz at 25%
Т/С = 2 Н2/ЭС maximum
Error increases by 10 times
per decade according to decade
In VM BOS EON. “Example: Vin
100 KHZ decade, error is +50 KHz.
Frequency stability
Long term drift: D 1079/yr. maximum
1 х 1077//mo. maximum
Short term drift: 5 x 10798/hr. maximum
Residual FM: 100 Hz maximum as measured in a
40-kHz bandwidth
RF output level
Range: -111 dbm (.7 pv) to 0 dbm (223 mV)
in 1 db steps and 1 db vernier
Accuracy: =2>"а5
RF output impedance 50 Game at L.3:1 maximum VSWR
Amplitude modulation (with OAM-1 plug-in)
Modulation range
INT: 0-30% at 3% maximum distortion
EXT: 0-30% at 3% maximum distortion
30-50% at 10% maximum distortion
TABLE 2-1. SPECIFICATIONS (CONT)
Modulation frequencies
INT: Selectable 400 Hz or 1 kHz +5%
EXT: <50 Hz to >20 kHz +1 db
referenced to 1 kHz
Ext. modulation sensitivity: Requires 0.5 V rms +20% for
30% modulation at 400 Hz & 1 kHz
Ext. modulation input
impedance: 240 KO ае ЕН?
Audio output (front panel output)
Output impedance: 600 ohm +20%
Output level: Adjustable «10 mV to »1 У rms
into a 600-ohm load
Distortion: 1% maximum
Frequency: Selectable 400 Hz or 1 kHz +5%
Frequency modulation (with ODM-1 plug-in)
Deviation range: 0-60 kHz peak minimum
Deviation rate
INT: 1 kHz +5%
ЕХТ: <50 Hz to >3 kHz at -3 db
referenced to 1 kHz
Ext. modulation sensitivity: 400 mV rms +10% for 5 kHz peak
deviation in narrowband "v"
position and 50 kHz in wideband
"/" position
Ext. modulation input
impedance: 600 ohm +20%
Audio output (front panel output)
Output impedance: 600 ohm +20%
Output level: Adjustable «10 mV to >1V rms
into a 600-ohm load
Distortion: 196 maximum
Frequency: 1 kHz =5%
ТАВЬЕ 2-1.
SPECIFICATIONS (CONT)
FREQUENCY METER FUNCTION
Measure input sensitivity:
Measure input impedance:
Measurement accuracy:
Zero beat indication
Та а ај
Speaker:
Headphone:
50 “KHz to 1 MHz <50 mv rms
ДИ мн» со 500 MHz < 6 mV rms
502 at 1.2:1 maximum VSWR
A signal can be measured to the
frequency accuracy of the inter-
nal time base. (See Frequency
Accuracy under Generator Func-
tion this Table).
Indicates beat notes below 50 kHz
and used to zero beat below
audible range
With maximum volume and l-kHz
beat note speaker produces
greater than 10 mW of audio
at the rated measure sensitivity
700 mV rms minimum at 1-kHz beat
note at rated input sensitivity
and maximum volume with a
source impedance of 560 +20%
AMPLITUDE MODULATION MONITOR FUNCTION (WITH OAM-1)
Ranges:
АССЫ асу:
Modulation frequency range:
Sensitivity:
Distortion analyzer output
Output level:
3 db bandwidth:
Source impedance:
Octo 30% and осо 100% (usable
to 9596)
21,0% Or ТЫЛП Seale ак I KHZ
<5 5)0) HZ (ШӨ > 3 KHZ ав 8 (016) вое
enced to 1 kHz
80 mV rms from 50 kHz to 1 MHz
10 mV rms from 1 MHz to 500 MHz
referenced to MEASURE INPUT
SOO why EMS св ОЗ по Ell Seale
deflectaon one CRE ар Ul kHz
<50 HZ ЕО > 3 KHZ
1 ко =20%
TABLE 2-1.
SPECIFICATIONS
(CONT)
FREQUENCY MODULATION MONITOR FUNCTION (WITH ODM-1)
Ranges:
Displayed deviation accuracy
1 kHz deviation rate:
50 Hz to 3 KHZ deviation
rate:
Sensitivity for operate light:
Sensitivity for overload light:
Modulation bandwidth:
Distortion analyzer output
Signal output level:
DC output level:
3 db bandwidth:
Source impedance:
l5 KHZ EOL Бийт Scale oh СЕТ
ЕЕ ОР KHZ EOL ЕО Seale On CRE
Е Бара EOE EU ОС, ON CRT
OO HZ ESO RSD.
100 HZ = / OL TR S.D.
<50 mv EMSs from 50 КН? to 1 MHZ
баш EMS СЕЗ ар EEOM Jb MHZ tO 500
MHZ referenced to MEASURE INPUT
20db + зар above "operate”
sensitivity
3570) HE Ее) BS Та сене Кар мое
enced to 1 kHz
1.5 У р-р +10% at 5 kHz peak
deviation
Al NL EMOS
& Б@ HZ EO E3 KHZ (LEL EO lL KHZ)
1 КО =20%
OSCILLOSCOPE FUNCTIONS - ОАМ-1
Vertical amplifier
Sensitivity:
Bandwidth (3 db):
Input impedance:
300 mV p-p +10% for full scale
deflection
50 Hz to 30 kHz (-3 db referenced
ОН)
100 КО ғ20% at 1 kHz
TABLE 2-1. SPECIFICATIONS (CONT)
Attenuation
Internal: Fixed steps of 1:1 and 3:10
External: Continuously variable 1:1 to
1:100
Horizontal amplifier
Sensitivity: 0.5 У o-p maximum per inch
deflection
Input impedance: 2500 KO at 1 KHZ
Sweep range
Low: 50 Hz to 500 Hz, variable
High: 500: HZ to 5 kHz, variable
Sweep type: Recurrent
Synek Internal automatic
ae oa ë O
Vertical amplifier
Sensitivity: 70 mV р-р =10% for full scale
deflection
Frequency response. 50 Hz to 30 kHz (-3 db referenced
EO lL kHz)
Input impedance: 25 2076
Attenuation
Internal: Fixed steps Of 1:1, SLO and 1:10
External: Continuously variable 1:1 to
1.100
Horizontal amplifier
Sensitivity: 0.5 V р-р maximum per inch
deflection
Input impedance: 2500. ED al LÛ kHz
ТАВЉЕ 2-1.
Sweep range
Low;
High:
Sweep type:
Sync:
SPECIFICATIONS (CONT)
50 HZ EO 500) HZ, variable
ЗОО НЕ EOS kHz, Variable
Recurrent
Internal Automatic
MISCELLANEOUS
Dimensions:
Weight:
Input voltage:
Input power:
Operating temperature:
8 3/4" H x 125" И x 16" D maximum
95 Lbs
115V ac +10% single phase
50-400 на ог 11.5-15.0 У dc
60 watts maximum
00 С to +500C
ACCESSORIES SUPPLIED
BNC to UHF acaptor
AC 3-wire to 2-wire adaptor
Antenna
20 dB El Ob attenuator pad
DC power cord
AC power cord
RF cable
Oscilloscope shield (2 ea)
2-7/2-8
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i
SECTTONSTTT
CONTROLS AND INDICATORS
All control, indicator, and external connector functions are described
in Tables 1-2 through 1-4. Each listed control and indicator is
keyed to an associated front panel figure that identifies and locates
the item. A faceplate figure of each equipment with an associated
control and indicator table are presented as follows:
FM-2 748 Table 3-1 Figure 3-1
OAM-1 Table 3-2 Figure 3-2
ODM-1 Table 3-3 Figure 3-3
=
FREQUENCY METER / SIGNAL GENERATOR
ВР OUTPUT
DB. | 2
RN: 5; o HORIZ POS
VERI | в ў a VERT POS
pone 1 *INTENSITY
сие
MA
мења
UDIO OUT
je INT
OUT OUT/MOD
AUDIO
is Senin Saeed eee eT ica
VERT IN DIST
ANAL
ЗОРЕ AMPLITUDE MODULAT
LLO
Figure 3-1. ЕМ-2748 Front Panel
BEZ
TABLE 3-1. MAINFRAME CONTROLS AND INDICATORS
FIG. 3-1 PANEL
NUMBER MARKING ТУРЕ FUNCTION
1
100 MHz Rotary switch,
five-position
Controls frequency
in four steps of
Dial marking: 100 MHz each.
0-1-2-3-4
2 10 MHz Rotary switch, Controls frequency
10-position in nine steps of
Dial marking: 10 MHz each.
0-1-2-3-4-5-6-
7-8-9
3 1 MHz Rotary switch, Controls frequency
OFFSET 2 MHZ FOR 10-position in nine steps of
MOD MEAS 1 MHZ each.
Dial marking:
0-1-2-3-4-5-6-
7-8-9
4 100 KHz Rotary switch, Controls frequency
WIDEBAND FM "у" ll-position in nine steps of
POSITION 100 kHz each. "'v"
position switches
the O-1 kHz variable
resistor (item 7)
Dial marking:
0-1-2-3-4-5-6-
7-8-9-V into circuit with
continuous control
over the range of
l MHz.
5 10 KHz Rotary switch, Controls frequency
NARROWBAND FM "V"| 11-position in nine steps of
POSITION ROS kHz. "ми
position switches
the 0-1 kHz variable
resistor into cir-
Dial marking:
0-1-2-3-4-5-6-
7-8-9-V cuit with continuous
control over the
range of 100 kHz.
6 KHz Rotary switch, Controls frequency
Dial marking:
0-1-2-3-4-5-6-
7-8-9-V
ll-position
in nine steps of
ЕНЕ posstion
switches the 0-1 kHz
variable resistor
FEO Gireuit wich
continuous control
over the range of
LO KHZ.
3-3
ТАВЬЕ 3-1.
MAINFRAME CONTROLS AND INDICATORS (CONT)
FIG. 3-1 PANEL
NUMBER MARKING TY PIE FUNCTION
0-1 KHz
Dial marking:
0-1-2-3-4-5-6-
7-8-9-10-0UT
8 MEASURE INPUT
9 RF OUTPUT
10 VERNIER
О САБ
ДЕ! PWR
IN/AC
OUT/DC
152 PWR
13 10 MHz
IN
OUT
Variable
resistor
Connector,
BNC Female
Attenuator,
scaled in
-dbm (0 to
=110 11 Lab
steps)
Variable
resistor
Switch,
pushbutton
Light
Switch,
pushbutton
Controls frequency
continuously over
four ranges:
0-1 kHz
0-10 kHz (with
ПЕН control
in У position)
0-100 kHz (with
ШО ЕНУШ control
їп V position)
0-1 MHZ (with
100 kHz control
іп V кроз Стоп)
Frequency range is
0-1 kHz when 1 kHz,
ОКН, OE ОО” kHz
eontrols are not in
EV ров Ion:
Input connector
Controls RF output
and reads directly
in -dbm into 50
ohns.
Controls RF output
level over greater
than 1 db range.
Controls power
supply.” Push to IN
position for ac
Operation. Push
to OUT position for
dc operation.
Indicates output
from internal power
supply.
Applies 10 MHz sig-
nalditectly from
TCXO crystal to
detector. Produces
audio frequency at
phone jack with same
accuracy as ТСХО.
ЕТС.
МОМВЕК
14
15
16
EZ
19
T9
20
21
МА
TABLE 3-1.
AUDIO
IN/BEAT
OUT/MOD
BEAT
VOLUME
AC/DC
AC
DC
AUDIO OUTPUT
RE “OUTPUT
CHASSIS
CONNECTOR
OSL REH.
MODULE)
PIT
MAINFRAME CONTROLS AND INDICATORS (CONT)
PANEL
MARKING TYPE
Switch,
pushbutton
Light
Variable
resistor
Connector,
socket
Fuse, .75-A
Fuse, 4-A
Connector,
phone jack
Connector
NA
FUNCTION
Switches loudspeaker
into beat detector
circurct. Should" be
in the IN position
at all times except
when a plug-in
module is used.
Provides visual
indication of beat
note when frequency
15 less than 50 kHz.
Controls speaker
volume and output
at AUDIO OUTPUT
connector.
Provides connection
EO AC OF ас source.
Protects 115/230 V
ас input circuits.
Protects dc input
УСС.
Supplies audio out-
put signal.
Supplies calibrated
output controlled
by RF OUTPUT
attenuator.
10 MHz signal from
тсхо BULLS at a
level of 0.5 V p-p
into a 5001 load
and with a source
impedance of 500 .
Is dc coupled and
requires a capaci-
tively coupled load.
3-5
TABLE 3-1. MAINFRAME CONTROLS AND INDICATORS (CONT)
FIG. 3-1 PANEL
NUMBER MARKING ТУВЕ | FUNCTION
Pinu2 Chassis ground
Pings Shield ground for
ping Di
Pin 4 Shield ground for
DIDAL2.
Pin 6 Shield ground for
pin 14.
Pin 8 Shield ground for
pino.
Piney OSV лав ELO WEE
1 mV rms maximum
ripple at 1 A maxi-
mum current
Pin 10 Shield ground for
pinel:
Pine kl Amplitude modulator
input. Bandwidth
OE SO не COC 2O Hz.
Input impedance is
500 ohms +20%.
Sensitivity. is 75 МУ
rms. 510%! FOE 30%
amplitude modula-
ELON. те ас
coupled and must be
driven from a
Capacitively coupled
source.
Pin 12 Frequency modulator
input. Bandwidth
1S CSO H2 CO 23 kHz.
Input impedance is
Вале Пе EO О ЕЕ
Sensitivity is 100 mv
ENS ESA преси kHz
modulation with
variable in 10 kHz
decade and 100 mv
Ins +50. рек 1O0 KHZ
modulation with
variable in 100 kHz
decade.
PIG.
ee
TABLE 3-1.
MAINFRAME CONTROLS AND INDICATORS
Audio input to Audio
Amplifier.
impedance
ohms +20%
Bandwidth
to >5 kHz.
75 mV p-p
i kHz to produce
5 V р-р across
speaker at maximum
volume.
2 MHz IF with nomin-
al 300 source
impedance.
is set at
rms into load impe-
dance of 200 ohns.
3 db bandwidth is
60 kHz minimum and
90 kHz maximun.
(CONT)
PANEL
MARKING TYPE FUNCTION
Pin 14
Pin 16
Input
те 250
ас кна
< 5040) 152
Requires
+2076, ас
Level
PASION
9 RANGE
2 s CARRIER LEVEL
СЕМ. „4
COYERTICAL SET
100%
ovERT MODE Ne o MOD MODE
МЕҢІ САМ s e + INT MOD/AUDIO OUT
г DANT.
MOD/AUDIO OUT FREQ
| VERT IN
| OSCILLOSCOPE A
08263
Figure 3-2. OAM-1 Front Panel
TABLE 3-2. ОАМ-1 CONTROLS AND INDICATORS
ЕТС. 3-2 PANEL
NUMBER MARKING ТУРЕ FUNCTION
1 VERT POS Variable Controls.vertical positron OE
(Outer knob) resistor CRT:trace.
INTENSITY Variable Controls brightness of CRT
(Inner knob) resistor trace. Used with FOCUS control
EO Obtain Clear Екасе:
2 RANGE Switch,
(Outer knob) three-
position
GEN 30% Enables internal or external
modulation of Mainframe carrier
upoctox305.
3096 Provides oscilloscope sensitivity
for measuring of modulated
carriers up to 30%.
10096 Provides oscilloscope sensitivity
for measuring of modulated
carr iets Up to, 10025;
CARRIER LEVEL | Variable Calibrates modulation
| (Inner knob) resistor sensitivity.
8 VERT MODE Switch,
(Outer knob) four-
| position
MEAS AM Modulated signal to be measured
is applied to oscilloscope
vertical amplifier input.
CARR SET Carrier, minus modulation, is
applied to oscilloscope vertical
amplifier input.
VERT SET Zero signal (ground) is applied
to oscilloscope vertical
amplifier input.
EXT Oscilloscope vertical amplifier
input is switched to VERT IN
connector.
EE SA
NUMBER
СОПЕ
TABLE 3-2.
УЕВТ САТМ
(Inner knob)
VERT IN
DIST ANAL
MOD/AUDIO
OUT FREQ
1 kHz
400 Hz
AUDIO OUT
600 2
EXT MOD/
HORIZ IN
Variable
resistor
Connector,
BNC
Jack
Switch,
two-
position
Connector,
BNC
Connector,
BNC
ОАМ-1 CONTROLS AND INDICATORS (CONT)
PANEL
MARKING тура
FUNCTION
Varies level of external signal
applied to VERT IN connector.
Effective when VERT MODE switch
тапа Ех posrtion' only.
Provides connection to oscillo-
scope vertical amplifier input
when VERT MODE switch is at EXT
position. External signal level
is controlled with VERT GAIN
control.
Provides demodulated audio for
output to a Distortion Analyzer
and regulated +9 dc at 50 mA
(max) for FM accessory items.
Controls frequency of the
internal modulation oscillator.
Connects 400 Hz or l kHz signal.
Level is controlled from O to
1 V rms by INT MOD/AUDIO OUT
Control.
Connects an external modulation
tone to modulation circuit when
MOD MODE switch is at EXT
position.
Connects an external horizontal
drive when MOD MODE switch is
at EXT HORIZ position (no inter-
nal sync from oscilloscope
vertical amplifier).
TABLE 3-2. OAM-1 CONTROLS AND INDICATORS (CONT)
ЕТС. 3-2 PANEL
NUMBER MARKING TYPE FUNCTION
MOD MODE Switch,
(Outer knob) three-
position
INT Connects internal sweep generator
(synchronized by oscilloscope
vertical amplifier signal) to
oscilloscope horizontal ampli-
fier input. Also connects
internal modulation oscillator
(400 Hz or 1 kHz) output (level
controlled by INT MOD/AUDIO OUT
control) to internal AM ampli-
fier to internally modulate
Mainframe carrier up to 30%.
EXT Connects internal sweep generator
(synchronized by oscilloscope
vertical amplifier signal) to
oscilloscope horizontal ampli-
fier input. Also connects EXT
MOD/HORIZ IN connector to input
of internal AM amplifier to
externally modulate Mainframe
carrier up Бо 30%.
EXT HORIZ Connects oscilloscope horizontal
amplifier to EXT MOD/HORIZ IN
connector to enable external
sweep of oscilloscope. Also
disconnects input to internal
AM amplifier.
INT MOD/ Variable Controls internal modulation
AUDIO OUT resistor level when MOD MODE switch is at
(Inner knob) power INT position, controls level of
switch 400-Hz and 1-kHz tone (available
PWR OFF at AUDIO OUT connector) from 0
to 1 У rms, and controls power
to OAM-1 module.
10 SWEEP RANGE Switch, Provides coarse control of sweep
(Outer knob) two- speed. 15 switched out of cir-
position cuit when an external horizontal
HI input signal is used and MOD
Lo МОРЕ is at EXT HORIZ.
TABLE 3-2. ОАМ-1 CONTROLS AND INDICATORS (CONT )
FUNCTION
SWEEP SPEED Variable Provides fine control of sweep
(Inner knob) resistor speed.
HORIZ POS Variable Controls horizontal position of
(Outer knob) resistor CRT trace.
FOCUS Variable Controls dispersion of CRT Ъеам.
resistor Used with INTENSITY control to
obtain sharp trace.
Rear panel Llowpin
Connector Pl plug
Bin #2 Chassis Ground
Pin #3 Cable SHEN for Pin #11
Pin #6 Cable Shield for Pin #14
Pin #8 Cable Shield for Pin #16
Pin #9 TOV асе 210% at 900 ma max.
(regulated)
Pin Audio modulation signal to
AM modulator in mainframe.
80 mV rms minimum with R2
full СИ and S-6 in Int.
рова Lion. ШЕП 5-6 in Ext.
position level is proportional
со 1еуе1тарь1+еа EO ЈА, (15
ШУ АО LOO mv cms at ја).
Output impedance 10 ohms +20%.
Recovered audio out to audio
amplifier mainframe. Output
impedance 120 ohm +20% at
1 kHz with level proportional
СОТТО Е modulation. TOO MV
MS О ОЖ EOE Full scale
Modula ton на ке. 30% and 100%.
ON MONITOR
OSCILLOSCOPE DEVIAY
——— |
57650
0
1
ODM-1 Front Panel
Figure 3-3.
3-13
TABLE 3-3.
FIG. 3-3 PANEL
NUMBER MARKING TYPE
1 VERT CENTER
(Outer knob)
INTENSITY
(Inner knob)
2 OPER
3 OVLD
4 HORIZ CENTER
(Outer knob)
FOCUS
5 VERT IN
(Outer knob)
INT
EXT
Variable
resistor
Variable
resistor
Indicator
light
Indicator
bight
Variable
resistor
Variable
resistor
Switch,
two-
position
ODM-1 CONTROLS AND INDICATORS
FUNCTION
Controls vertical position of
CRT trace.
Comtrolssbrichtness ОҒ СЕТ
trace. Used with FOCUS соп-
trol to obtain clear trace.
Indicator is off when too
little or too much IF signal
is applied to the input.
Indicator is on when IF sig-
nal level is in acceptable
range.
NOTE: “OPER indicator is
linked with OVLD indicator
so that both are never on
at the same time.
Indicator is off at all times
except when IF signal is
excessive. ОМЕР goes off
and OPER comes on when IF
signal is decreased to
proper level.
Controls horizontal position
СЕ CRT trace.
Controls dispersion of beam
on CRT. Used with INTENSITY
control to obtain sharp trace.
Switches oscilloscope vertical
input to output of internal
demodulator.
Switches oscilloscope vertical
input to VERT IN connector.
TABLE 3-3.
ODM-1 CONTROLS AND INDICATORS (CONT)
e =S PANEL
NUMBER MARKING TYPE FUNCTION
5 VERT GAIN
Cont (Inner knob)
CAL
6 SWEEP RANGE
(Outer knob)
HI
LO
SWEEP SPEED
(Inner knob)
7 DEV RANGE
1x5 (kHz
5 KHZ
15 kHz
8 MOD MODE
INT/COMB
EXT
EXT HORIZ
Variable
resistor
Switch,
two-
position
Variable
resistor
Switch,
three-
position
Switch,
three-
position
Varies vertical gain. When
VERT ZN-switch. is at EXT
position, CAL position indi-
cates the maximum sensitivity
end of its range.
Provides coarse control of
sweep speed. Is switched out
Of circuit when an external
horizontal input signal is
used and MOD MODE switch is
at EXT HORTZ
Provides fine control of sweep
speed.
Selects calibrated vertical
input ranges.
Switches an internal 1-kHz modu-
lation tone (controlled by INT
MOD/AUDIO OUT control) and an
external signal at the EXT MOD/
HORIZ IN connector into the
modulation circuit. The exter-
nal modulation tone supplied
to EXT MOD/HORIZ IN connector
is combined with the internal
l-kHz tone.
Removes the internal 1-kHz
signal from the modulation cir-
cuit. Only the signal from
EXT MOD/HORIZ IN connector is
inztcthe circuit,
Switches EXT MOD/HORIZ IN con-
nector into the horizontal
drive circuit.
ЕТС. 3-3
МОМВЕК
9
10
ДУ]:
ШЕ?
13
TABLE 3-3.
PANEL
MARKING
DIST ANAL
INT MOD/
AUDIO OUT
AUDIO OUT
| VERT IN
6009
EXT MOD/
HORIZ IN
Rear panel
connector Pl
Pin
Pin
Pin
Pin
2
4
ODM-1 CONTROLS AND INDICATORS (CONT)
TYPE
Connector,
BNC
Jack
Variable
resistor,
switched
Connector,
BNC
Connector,
BNC
16. рп
plug
FUNCTION
Provides connection to vertical
amplifier when VERT IN switch
IS at EXT.
Connects demodulated audio
Output to a Distortion Analyzer.
Controls internal modulation
level when MOD MODE switch is
at INT/COMB. Also controls
level of 1 kHz tone (available
at AUDIO OUT connector) from
О to ТУ rms and controls power
to ODM-1 module.
Connects 1 kHz output signal.
Level is controlled from 0 to
1 У rms by INT MOD/AUDIO OUT
control.
Connects an external modula-
tion tone to modulation circuit
when MOD MODE switch is at INT/
COMB (оре EXT
Provides an external horizon-
tal drive when MOD MODE switch
is at EXT HORIZ.
Chassis ground
Cable shield for pin 12
Same as DIST ANAL output
Cable shield for pin 14
Cable shield for pin 16
+9 V ас +10% at 900 mA maximum
(regulated)
TABLE 3-3. ODM-1 CONTROLS AND INDICATORS (CONT)
PIG. 73-3 PANEL
NUMBER MARKING FUNCTION
153 Audio signal from internal 1 kHz
Cont Өссе л аро wns 50) Ну! EO 3 KHZ
external modulation source.
Source impedance is less than
100 ohms. Level set at 500 mV
rms +5% with 400 mv rms into
EXT MOD/HORIZ IN jack or greater
than 500 mV rms from internal
modulation source with AUDIO OUT
level at maximum. Levels are
set inco SG K load:
Cable suveid for" pin 5.
Recovered audio out signal to
audio amplifier in Mainframe.
Should be greater than 40 mV
rms into a 100-ohm load for
full scale deflection. 3-db
bandwidth should be greater
than 50 HZ EO S&S KHZ.
2-MHz IF input from Mainframe
al level whe 2.5 MV EMS ES) (оће
at rated sensitivity of Main-
frame. Input impedance is 200
ohms nominal.
(ж
|
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ПРВЕ را س و سے e
ah 一
SECTION IV
OPERATING PROCEDURES
4.1 POWER SUPPLY CONNECTIONS (MAINFRAME)
TO use а ас. source, 151910155
a. Connect power to the AC/DC connector.
b. Use special dc cable assembly provided to connect to a car
or truck battery.
NOTE: Make certain that the external source provides
a negative ground to prevent reverse polarity from
blowing the ас fuse (FM-2748 case is connected to the ас
negative line).
TO use а 115 Уу ас source, plug power сока into 115 М ас 3-ріп typ
source.
NOTE: The Mainframe is supplied pre-set to 115 V ac
for use in North America unless otherwise indicated
by a decal over the AC/DC socket. Power cord supplied
is 3-pin for use with 115 V grounded mains supply.
To convert to 230 V ac operation:
a. Remove cover by removing four screws on back of case.
b. Set voltage switch marked 115 at 230 V setting (Switch
is located behind left-hand panel and is exposed when
cover is removed).
c. Replace cover.
d. Plug into source.
e
4.2 START PROCEDURE (ЕМ-2748)
To switch on power:
a. For dc, set PWR switch at OUT/DC.
b. For ac, set PWR switch at IN/AC.
NOTE: To obtain accuracy of 1 x 1020 compare
accuracy against higher accuracy standard and
adjust TCXO after 1 hour temperature soak.
4.3 SIGNAL GENERATOR FUNCTION -- CW SIGNAL ONLY (No Plug-in Required)
4.3.1 SET-UP PROCEDURE.
а. Push lO MHZ switch ЕО OUT
b. Make output connection to RF OUTPUT connector as shown in
Figure 4-1.
C. For output levels between -110 dbm and O dbm, connect
load directly to RF OUTPUT connector and set output
level with RF OUTPUT attenuator. For output levels
between -130 dbm and -20 dbm, connect load to RF
OUTPUT connector through RFA-20 pad and increase RF
OUTPUT attenuator reading by -20 dbm.
NOTE: The RF OUTPUT VERNIER control allows infinite
resolution on the output level with the RF OUTPUT
attenuator indicating the output level in -dbm when the
RF OUTPUT VERNIER control is at the 0 CAL position.
d. Dial desired frequency on the frequency controls.
e. Adjust signal level with RF OUTPUT controls.
CAUTION
Do not key the transmitter while directly
connected to FM-2748 RF output. Keying will
burn out the RF fuse assembly.
LOAD
(RECEIVER)
OPTIONAL OPTIONAL
FM 一 2748
] С] CKO
(2)
(3) (1) (1) (4)
ITEM DESCRIPTION
1 BNC CONNECTOR MALE
2 RG—58U COAX CABLE
3 RFA-20 ATTENUATOR
4 BNC TO UHF ADAPTER, UG—273/U
Figure 4-1. Connections for Signal Generator Function
4.3.2 MANUAL FREQUENCY SWEEP. Setup base frequency and output
level as described in 4.3.1.
4.3.2.1 TO Manually Sweep 1 MHz.
а. сее LOO REZ frequency. control at У.
b. Rotate 0-1 KHz frequency control through its full range.
Output frequency increases by 1 MHz.
4.3.2.2 To Manually Sweep 100 kHz.
a. Set 10 KHz frequency control at V and 100 kHz control
mons eo) Wc
b. Rotate 0-1 KHz frequency control through its full range.
Output frequency increases by 100 kHz.
4.3.2243 то’ Manually Sweep: 10 kHz.
a. Set 1 KHz frequency control at V and 100 kHz control
im(ons ie) Ac
b. Rotate 0-1 KHz frequency control through its full range.
Output frequency increases by 10 kHz.
4.4
4.4.1
conne
PLACE RFA—20 IN
THIS LINE.
FREQUENCY METER FUNCTION (No Plug-in Required)
ANTENNA SET-UP. Connect antenna provided to MEASURE INPUT
GEOL:
CAUTION
Do not overload the instrument with excessive RF signal.
Decrease input level at MEASURE INPUT, if required by de-
creasing the length of the antenna or by adding 20 dB pads
between the antenna and the RF ONPUT connector as required.
DIRECT CONNECTION SET-UP.
Connect RFA-60, load, and unit under test as shown in
Figure 4-2.
ТЕ ЕМ-2748 is overloaded, connect RFA-20 in line between
FM-2748 and RFA-60.
FM 一 2748
MEASURE INPUT
Е OVERLOAD OCCURS,
RF WATT METER
OR RF LOAD
TRANSMITTER
TRANSMITTER POWER MUST BE
GREATER THAN 1 WATT AND MUST
NOT EXCEED 60 WATTS
*FREQUENCY RESPONSE ОЕ RFA—60 IS 150 — 160 MHz
Figure 4-2. Direct Connection, Frequency Measuring Function
4.4.3 KNOWN TRANSMITTER FREQUENCY. When the transmitter frequency
is within a few hundred hertz of a known channel frequency:
CAUTION
Transmitter power should not exceed
60 watts.
а. Риза LO ME Ze SWI ECD to OUT,
b. Push AUDIO switch to IN/BEAT.
NOTE: For remote presentation of beat note, connect
a speaker to the AUDIO OUTPUT jack. Use VOLUME control
to adjust beat note level. Internal speaker is dis-
connected when an external unit is connected into the
AUDIO OUTPUT jack.
c. Set frequency controls at channel frequency.
d. Key transmitter.
e. Observe beat note and reduce to zero by adjusting 0-1 KHz
frequency control. Ensure that no frequency control is at
V position.
f. Read actual transmitter frequency from frequency control dials.
4.4.4 UNKNOWN TRANSMITTER FREQUENCY. When only the approximate
transmitter frequency is known (within a range of 1 megahertz):
a. Set megahertz frequency controls (100 MHz, 10 MHz, and 1 MHz)
at a frequency slightly below presumed value.
b. Set 100 KHz frequency control at V.
c. Search for zero beat by turning 0-1 KHz frequency control.
а. Observe zero beat and read least significant decimal of
0-1 KHz frequency control (reading is in 100 kHz per decimal).
е. Set 100 KHz.frequency control at value obtained in step d.
Е. Set 10 KHz frequency control at V.
4.5
се
Repeat steps с апа а (reading is in 10 kHz per decimal).
Set 10 KHz frequency control at value obtained.
бег. 1 KHZ frequency control асау:
Repeat steps c and d (the reading is in 1 kHz per decimal).
Set 1 KHz frequency control at value obtained in step j.
Turn 0-1 KHz frequency control until zero beat is obtained.
Read exact frequency from all seven frequency control dials.
PRELIMINARY OSCILLOSCOPE SET-UP (MAINFRAME/OAM-1)
Apply power to Mainframe.
Apply power to OAM-1 module by turning INT MOD/AUDIO OUT
control CW. Push AUDIO switch on Mainframe to OUT/MOD.
Allow approximately 1 minute for warm-up.
Set ОАМ-1 controls as follows:
MOD MODE INT
INTENSITY As required
FOCUS For sharpest trace
VERT POS For desired position
HORIZ POS For desired position
VERT GAIN Fully ccw
Adjust VERT РОС, INTENSITY, HORIZ РОЗ, andoFOCUS controls
for sharpest trace and desired position on CRT.
4.6 AMPLITUDE MODULATED SIGNAL GENERATOR (MAINFRAME/OAM-1)
The Mainframe with the OAM-1 module are used as a signal generator
that can be internally amplitude modulated by either 400 or 1000 Hz
or externally modulated with frequencies Еком к 50 Hz to >20 kHz.
4.6.2
INTERNAL MODULATION.
Set Mainframe frequency controls at 12.000 MHz.
Push 10 MHz switch on Mainframe to IN.
Set ОАМ-1 VERT MODE switch at VERT SET.
Adjust VERT POS control to position trace at VERTICAL SET
line of graticule.
Set VERT MODE switch at CARR SET.
Adjust CARRIER LEVEL control to position trace at CARRIER
SET line of graticule.
Set RANGE switch at GEN 30%.
Set VERT MODE switch at MEAS AM.
Set MOD/AUDIO OUT FREQ control at desired modulation frequency
(400 to 1000 Hz) and adjust INT MOD/AUDIO OUT control for
desired percentage of modulation (30% maximum) .
Place 10 MHz switch on Mainframe at OUT.
NOTE: The FM-2748 is modulated at the percentage
set in step j +10% for any frequency selected with the
frequency controls.
EXTERNAL MODULATION.
Connect external modulating source to ОАМ-1 EXT MOD/HORIZ IN
connector (500 mV rms +20% for 30% modulation, <50 Hz to >20 kHz).
Set Mainframe frequency controls at 12.000 MHz.
Push 10 MHZ switch on Mainframe to IN.
Set ОАМ-] VERT MODE switch at VERT SET.
Adjust VERT POS control to position trace at VERTICAL SET
line of graticule.
Set VERT MODE switch at CARR SET.
а. Adjust CARRIER LEVEL control to position trace at CARRIER SET
line of graticule.
h. Set RANGE switch at GEN 30%.
ј. Set VERT MODE switch at MEAS AM.
К. Set MOD MODE switch at EXT.
%
1. Set level of external modulating source for desired percen-
tage of modulation (30% maximum at 3% distortion). Increasing
modulating source level by 125 mV rms produces approximately
50% modulation at 10% maximum distortion.
m. Push 10 MHz switch on Mainframe to OUT.
NOTE: The FM-2748 is externally modulated at the
percentage set in step 1 +10% for any frequency set by the
frequency controls.
4.7 PRELIMINARY OSCILLOSCOPE SET-UP (MAINFRAME/ODM-1)
a. Apply power to Mainframe.
b. Apply power to ODM-1 module by turning INT MOD/AUDIO OUT
control CW. Allow approximately 1 minute for warm-up.
Set AUDIO switch on Mainframe at OUT/MOD.
с. Set ODM-1 controls as follows:
MOD MODE INT
INTENSITY Buy Cw.
VERT GAIN CAL
VERT POS Mid position
HORIZ POS Mid position
FOCUS For sharpest trace
4.8 INTERNALLY FREQUENCY MODULATED SIGNAL GENERATOR (MAINFRAME/ODM-1)
4.8.1 NARROWBAND (0-5 kHz) PEAK DEVIATION. Example:
MHz to 5 kHz peak deviation.
Modulate 273.939
а. Set controls аз follows:
Frequency controls
10 MHZ
DEV RANGE
VERT IN
VERT GAIN
MOD MODE
INT MOD/AUDIO OUT
0-1 KHz
008.0V00
IN
5 KHz
INT
CAL
INT /сомв
CEN (ПОНОВЕ)
О (повконЕ)
b. Turn INT MOD/AUDIO OUT control until wave height reaches
5 KHZ.
с. Push 10 MHz switch to OUT.
d. Set Mainframe frequency controls at desired carrier frequency
(2973099390 MHz) +
e. Set 0-1 KHz frequency at same value as 10 KHz and 1 KHz
frequency controls (3.9).
f. Set 10 kHz frequency control at V.
g. Mainframe FM-2748/0DM-1 is now generating 5 kHz peak deviation
ас 273.939 MHZ,
4.8.2 WIDEBAND (5-15 kHz) PEAK DEVIATION.
273 9298 MEZ 0:15 KHz.
a. Set controls as follows:
Frequency controls
10 MHz
DEV RANGE
VERT IN
VERT GAIN
MOD MODE
INT MOD/AUDIO OUT
0-1 KHz
Example: Modulate
008.М000
ТМ
шъ Киа
INT
CAL
INT/COMB
Fully CCW
О (not OUT)
Turn INT MOD/AUDIO OUT control until wave height reaches 15 kHz.
Push 10 MHz switch to OUT.
Reset Mainframe frequency controls at carrier frequency
(277329398 MHZ)
Set 0-1 KHz frequency control at value of 100 KHz and 10 KHz
frequency controls (9.39 or 9.4).
Set 100 KHz frequency control at V.
Mainframe/ODM-1 is now generating 15 kHz peak deviation at
27329398 MHZ.
WIDEBAND (15-60 kHz) PEAK DEVIATION
NOTE: The Mainframe/ODM-1 provides peak deviation
measurements to 15 kHz. However, peak deviations as
high as 60 kHz can be generated by the following procedure.
Example: Modulate 36.2471 MHz to 50 kHz peak deviation.
Set controls as follows:
Frequency controls 008.0V00
10 MHz IN
AUDIO OUT/MOD
INT MOD/AUDIO OUT ССИ (not off)
VERT IN INT
VERT GAIN CAL
DEV RANGE 5 kHz
MOD MODE INT/COMB
0-1 kHz О (not OUT)
Turn INT MOD/AUDIO OUT control until wave height reaches
one tenth of desired peak deviation (5 kHz).
Push 10 MHz switch to OUT.
Reset trequency controls to earrierstrequency “(23622471 MHz).
е. Set 0-1 KHz frequency control at same value as 100 kHz and
10 KHZ сопске с (2.37 "or 2.5).
Е. Set 100 KHz frequency control at У.
а. Mainframe/ODM-1 is now generating 50 KHz peak deviation at
36.247 MHz.
NOTE: In the example, the peak deviation of 5 kHz is set
up with the 10 KHz frequency control in the V position.
This is multiplied by 10 when the 100 KHz frequency con-
trol is set at V in step f. The peak deviation thus
becomes 50.0 kHz.
4.9 COMBINED INTERNAL/EXTERNAL (TWO-TONE) FM SIGNAL GENERATOR
(MAINFRAME /ODM-1)
a. Set Audio Oscillator at desired frequency and set at zero
output.
b. Connect Audio Oscillator to EXT MOD/HORIZ IN jack on ODM-1.
e. сев controls ав follows;
0-1 KHz On (POE OUD)
10 MHZ IN
AUDIO OUT /MOD
Frequency controls 008.VOO MHz (wideband deviation)
008.0\0 MHz (narrowband deviation)
VERT GAIN CAL
VERT IN INT
MOD MODE INT /COMB
DEV RANGE As required
INT MOD/AUDIO OUT CCW (AOE OEE)
d= Adjgust VERT CENTER to align Erace оп СЕТ.
e. Turn INT MOD/AUDIO OUT control CW until wave height reaches
desired peak deviation for the internal 1 kHz tone.
Е. Set MOD MODE at EXT. Increase Audio Oscillator output until
wave height on CRT reaches total peak deviation required for
the external tone.
g. Set MOD MODE at INT/COMB and 10 MHz at OUT.
Set Mainframe frequency controls at desired carrier frequency.
Example: 97.3527 MHz.
Set 10 KHz or 100 KHz frequency control at V position,
according to whether narrowband or wideband modulation is
required.
Set 0-1 KHz frequency control at the appropriate setting:
3.527 for wideband or 5.27 for narrowband.
Mainframe/ODM-1 is now generating two-tone frequency modulation
at the desired carrier frequency.
4.10 EXTERNALLY FREQUENCY MODULATED SIGNAL GENERATOR (MAINFRAME/ODM-1)
Repeat procedure of paragraph 4.8.4 with MOD MODE switch at EXT and
omitting internal modulation (step f).
NOTE: Internal 1 kHz modulation oscillator
is out of the circuit when MOD MODE is at EXT.
4.11 MEASUREMENT OF AMPLITUDE MODULATION (MAINFRAME/OAM-1)
a.
Set Mainframe frequency controls at frequency of transmitter.
Example: Transmitter frequency is 120.0261 MHz.
Offset Mainframe frequency +2 MHz, for above example:
118.0261 MHz or 122.0261 MHz.
NOTE: Always add 2 MHZ whenever possible.
Couple transmitter output to Mainframe MEASURE INPUT con-
nector via the antenna provided, or use RF cable input with an
RFA-60 attenuator in the line (see paragraph 4.4.1 or 4.4.2).
Set VERT MODE switch at VERT SET.
Adjust VERT POS control to position the trace on VERTICAL SET
line of graticule.
Set VERT MODE switch at CARR SET.
Adjust transmitter coupling to Mainframe and/or CARRIER LEVEL
control to position trace at CARRIER SET line of graticule.
Set RANGE switch at desired range (30% or 100% full scale).
Set VERT MODE switch at MEAS AM. Adjust transmitter modulation
to desired percentage as indicated by scope calibration scale.
To check distortion connect Distortion Analyzer to DIST ANAL
output and make distortion measurement.
4.12 AUDIO TEST TONE GENERATION (MAINFRAME/OAM-1)
Either 400 Hz or 1 kHz tone modulation developed by the Mainframe/
ОАМ-1 is available at all times at the AUDIO OUT 6009 connector
for testing of transmitters or repeaters.
a.
Connect transmitter microphone input to AUDIO OUTPUT 6002
connector.
Set MOD/AUDIO OUT FREQ switch at desired tone modulation
frequency, 400 Hz or 1 kHz.
Set INT MOD/AUDIO OUT control at level desired (a maximum
of 1 У rms into 600 ohms is available).
Mainframe/OAM-1 is now supplying a 400-Hz or 1-kHz tone with
600 ohms output impedance.
MEASUREMENT OF PEAK DEVIATION (MAINFRAME/ODM-1)
Set frequency controls at frequency of transmitter. Example:
transmitter frequency is 276.0359 MHz.
Offset Mainframe frequency by +2 MHz, for above example:
274.0359 MHz or 278.0359 MHZ.
NOTE: Always ааа 2 MHz whenever possible. The
polarity of the displayed deviation is only correct
when the Mainframe frequency is above the incoming
signal frequency.
Couple transmitter FM output to MEASURE INPUT connector via
antenna provided, or use RF cable input with an RFA-60
attenuator in the line (see paragraph 4.4.1 or 4.4.2).
Set other controls as follows:
VERT IN INT
10 MHz OUT
DEV RANGE As required
Key transmitter (do not modulate).
Increase RF input until OPER indicator lights.
ТЕ OVLD indicator lights, decrease RF input until OPER
indicator lights and OVLD indicator goes out.
Adjust VERT CENTER to align trace in center of CRT.
Modulate transmitter by voice or tone.
NOTE: A l-kHz note, variable from 0-1 V rms, is
available at AUDIO OUT.
Adjust SWEEP RANGE and SWEEP SPEED controls for number of
cycles to be displayed.
Use appropriate kHz scale on CRT to measure peak height of
wave. Check waveform visually for presence of distortion.
4.14
Monitor modulation aurally by adjusting VOLUME control to
desired listening level.
To investigate audio distortion further, connect a Distortion
Analyzer to DIST ANAL output.
AUDIO TEST TONE GENERATION (MAINFRAME/ODM-1)
NOTE: The 1 kHz modulation tone developed by Mainframe/
ODM-1 is available at all times at the AUDIO OUT connector
for testing of transmitters and repeaters.
Connect transmitter microphone input to AUDIO OUT.
Turn INT MOD/AUDIO OUT control to level desired (a maximum
of 1 V rms into 600 ohms is available).
The Mainframe/ODM-1 is now supplying а 1 kHz tone with 600
ohms output impedance.
4.15 GENERAL PURPOSE OSCILLOSCOPE (MAINFRAME/OAM-1)
The ОАМ-1 is used as a general purpose oscilloscope with the horizon-
tal sweep generated either internally or externally.
4.15.1 INTERNAL HORIZONTAL SWEEP.
Set MOD MODE switch at either INT or EXT.
Set VERT MODE switch at EXT.
For maximum sensitivity turn VERT GAIN control fully CW.
Connect signal to be displayed on CRT to the VERT IN connector.
NOTE: The nominal frequency response to the vertical «e
amplifier is 50 Hz to 30 kHz.
Adjust VERT GAIN control for suitable trace height.
Set SWEEP RANGE switch at HI or LO for coarse adjustment of
horizontal display.
Adjust SWEEP SPEED control for number of displayed cycles.
4-15
4.15.2 EXTERNAL HORIZONTAL SWEEP.
a. Set MOD MODE switch at EXT HORIZ.
b. Connect an external sweep source to EXT MOD/HORIZ IN connector
and adjust for desired oscilloscope sweep width (less than
175 mV rms рег inch ог defleetion).
с. Set VERT MODE switch at EXT.
d. For maximum sensitivity, turn VERT GAIN control fully си.
e. Connect signal to be displayed on CRT to VERT IN connector.
NOTE: The nominal frequency response to the vertical
апра Еее AS 5O0 HZ CO0 KHZ.
Е. Adjust VERT GAIN control for suitable trace height.
4.15.3 Х-Ү MODE OF OPERATION.
In some applications, it is desirable to display one signal versus
another (X-Y) rather than against time (internal or external sweep).
a. Set VERT MODE switch at EXT.
b. Set MOD MODE switch at EXT HORIZ.
с. Apply signal for X-axis display to EXT MOD/HORIZ IN connector.
d. Apply signal for Y-axis display to VERT IN connector.
e. Adjust VERT GAIN control for suitable trace height.
f. Adjust X-axis signal level externally for desired trace width
(less than 175 mV rms per inch width).
4.16 GENERAL PURPOSE OSCILLOSCOPE (MAINFRAME/ODM-1)
The ODM-1 is used as a general purpose oscilloscope with the hori-
zontal sweep generated either internally or externally.
4 16-1
4.16.3
in some
another
a.
be
INTERNAL HORIZONTAL SWEEP.
Set VERT IN switch at EXT.
For maximum sensitivity turn VERT GAIN control fully cw.
Connect signal to be displayed on CRT to VERT IN connector
(signal must be within 50-Hz to 30-kHz range).
Set MOD MODE switch at INT/COMB or EXT.
Adjust VERT GAIN control for suitable trace height.
Set SWEEP RANGE switch at HI or LO for coarse adjustment of
horizontal display.
Adjust SWEEP SPEED control for desired number of displayed
cycles.
EXTERNAL HORIZONTAL SWEEP.
Repeat 4.16.1 except set MOD MODE switch at EXT HORIZ.
Connect EXT MOD/HORIZ IN to external sweep signal source
and adjust amplitude for desired sweep width (less than
175 mV rms per inch width).
X-Y MODE OF OPERATION.
applications, it is desirable to display one signal versus
(X-Y) rather than against time (internal or external sweep).
Set VERT MODE switch at EXT.
Set MOD MODE switch at EXT HORIZ.
Apply signal for x-axis display to EXT MOD/HORIZ IN connector.
Apply signal for y-axis display to VERT IN connector.
Adjust VERT GAIN control for suitable trace height.
Adjust x-axis signal level externally for desired trace
width (less than 175 mV rms per inch width).
АРРЕМОТХ А
SECOND HARMONIC INFORMATION
The second harmonic of the FM-2748 from 250 MHz to 500 MHz is
Between 25) EO 40 ав аот ас the RE OUTPUT соппесвот ТЕ 1S Not
calibrated and will vary between units.
To measure frequencies from 500 MHz to 1 GHz set the FM-2748
frequency to one-half the frequency to be measured. To measure
FM or AM modulation of frequencies from 500 MHz to 999 MHz set
the FM-2748 frequency to one-half plus 1 MHz of the frequency to
be measured. Use minus 1 MHz for frequencies from 999 MHz to
1 GHz.
The measure input sensitivity for frequencies from 500 MHz to
ТСН мії vary from 60 millivolts to 230 milla3volts.
For FM generate, the peak deviation of the second harmonic will
be twice that of the fundamental.
For AM generate, the percent modulation of the second harmonic
has no real relation to the percent modulation of the fundamental;
therefore it cannot be predicted.
Раде 2-4 MEASUREMENT ACCURACY
Delete: Generator (A2,A3)
Add: Internal time base (see frequency accuracy under
"Generator Functions" in this table).
Page 2-5 Table 2-1, Specifications (cont. IR
After FREQUENCY MODULATION («th ПР after PRT OUT PARC V АТ |
MONITOR FUNCTION, BARTS UR AR ОГ
Add: (with ODM-1)
After Sensitivity for Opétate пулу vers ee
light, Add: Sensitivity ior НОО ИСКЕ :20 d +3 dB above
| "operate" sensitivity,
Page 2-6 ‘OSC ILLOSCOPE FUNCTIONS (ODM-1) Vertical Amplifier Sensitivity:
Delete: . "in 1,5 kHz range"
OSCILLOSCOPE FUNCTIONS (ODM-1) Horizontal Amplifier Input тредапее:,
Add: 25 PETI
Page 3-6 TABLE 3-1, MAINFRAME CONTROLS AND INDICATORS Em
Pin 11 ` Was: 75 mV rms +20% |
5: 75 mV rms +10% ч DE
Pin 12 Was: 80 mV rms +10% (2 places) |
Is: 100 mV rms +5% (2 places) Г |
Раде. 3-12,, At the end of table, add: =
| xl |
Rear panel Е!
Connector P1 16 pin plug PER
1 ше:
Pin #2: Chassis Ground Z 77%
Ріп 43: Cable Shield for Pin #11. ЕЗІНІН
Ріп #6: Cable Shield for Pin #14. үч
INSTRUMENTATION = MODEL ЕМ-2748 / ODM-1 |- 500783-250
LOS ANGELES, CALIF.
FORM NO. 180 1м 3-70 D-H
ADDENDUM
for
MODEL FM-2748/0DM-1
Manual Мо. 500783-250
Pin #8: Cable Shield for Pin #16.
Pin #9: 49V dc =10% at 900 mA Max. CATER RE
Pin #11: Audio modulation signal to AM modulator
in mainframe. 80 mV rms minimum with НА Ш
R2 full CW and :56 т Int. position.
With ‘S6 in Ext. position, level is pro- |.
portional to level applied to ЈА, (15 mV |.
+5% for 100 mV rms at J4). Output
impedance 10.4. +20%.
—ADDENDUM- DWG NO.
SHEET 1,1
1 (то: ливене мани ША уза MEM Iris ҺА
Доо! suit at" ой зоман”
| "m new VN МОПАШО OM ӘЗ ЛА”
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| cn ума B ЩІ. 1a MAT 7
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"4. б rer үз
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Recovered audio out to audio amplifier
mainframe. Output impedance 120 a
+20% at 1 kHz with level proportional
to 96 cf modulation, 100 mV rms +10% |
for full-scale modulation, i.e., >
and 100%.
Раде 3-17, Table 3-3, ODM-1, Controls and Indicators
Pin 12:
Page 4-4, Fig. 452
Under RFA-60,
Below transmitter block,
Page 4-9
4.8.1.а NOTE:
Page 4-11
4.8.4.с, Frequency Controls
` Was:
ls:
Below INTCMOD/AUDIO OUT;:: Add:
2002. +20%
Less than 100...
400 mV rms with 400 mV rms into....
500 mV rms +5% with 400 mV rms into..
2k ead
5.6К ¿a Load
an: Asterisk.
* Frequency re epee of RFA-60 is
150 - 160 MHz
12.000 MHz
8.000 MHz
008.000 MHz
008. VOO MHz (wideband од
008.0V0 MHz (narrowband deviation)
"Note: Ensure that the 0-1 kHz
frequency control is not at the OUT
position"
Repeat 4.18.1
Repeat 4,14, 1
"with DEV RANGE switch set at 1.5kHz'
"and DEV RANGE switch"
SINGER MILE ADDENDUM DWG NO.
INSTRUMENTATION MODEL ЕМ-2748 / ODM-1 . | 1-500783-250
LOS ANGELES, CALIF.
FORM NO. 182 (М 3-70 D-H
ЗНЕЕТ |,
REVISED |
АРРКОМЕО
за be МЕРУ E
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(ойын занаята и
соната 3
OAM-1 RUNNING CHANGES
Effective serial number: OAM-1 serial numbers prefixed with 566 and above.
Page 2-2: TABLE 2-1. SPECIFICATIONS
Amplitude modulation (with OAM-1 plug-in)
INT, Add: 30 to 100% at 10% maximum distortion
EXT, Was: 30-50% at 10% maximum distortion, Is: 30-100% at 10%
maximum distortion
Page 2-4: TABLE 2-1. SPECIFICATIONS (CONT)
AMPLITUDE MODULATION MONITOR FUNCTION (WITH OAM-1)
Ranges, Delete: (useable to 95%)
Page 3-8: Figure 3-2. OAM-1 Front Panel
RANGE, Was: GEN 30%, 30%, 100% Is: GEN 30%, MEAS 30 %, MEAS/GEN
100%
Page 3-9: TABLE 3-2. OAM-1 CONTROLS AND INDICATORS
Item 2, RANGE, Was: GEN 30 %, 30%, 100% Is: GEN 30%, MEAS 30%,
MEAS/GEN 100%
Function, 100% position, Add: Provides internal or external amplitude
modulation of the mainframe carrier up to
100 %.
Page 4-7: Paragraph 4.6.1 INTERNAL MODULATION.
g., delete the period and Ада: for up to 30 % modulation or set it to
MEAS/GEN 100% for greater than 30%
modulation,
Page 4-8: Paragraph 4.6.2
h., delete the period and Add: for up to 30% modulation or set it to
MEAS/GEN 100% for greater than 30%
modulation,
... source level by 125 mV rms produces
approximately 50% modulation..."
"2. source level to approximately 1.7 У rms produces
100% modulation, ,. "
"
1., lines 3 апа 4, Was:
Is: '
CLASS CODE
APPROVED
FORM NO. 160 iM 3-70 D-H
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ODM-1 RUNNING CHANGES
Effective ODM-1 Serial Number:
Page 3-13: Figure 3-3. ODM-1 Front Panel
7, Was:
DEV RANGE,
L5KHz.
t
}
|
|
|
|
j;
SKHZ-
[SkHz^
MDD MODE”,
Page 3-15: TABLE 3-3. ODM-1 CONTROLS
Item 7, Was: DEV RANGE Is:
1.5 kHz
9 kHz
15 kHz
Item 7, Add: VERT COUPLING Switch,
(Inner knob) two
AC position
DC
Item 8, Was: MOD MODE
Variable
resistor
Item 8, Add: DC BAL
(Inner knob)
Serial numbers suffixed with 04058 and above,
Is:
ac DEV RANGE
ER
T ir es
S
ISkN27
Омор море.
9 DC BAL
AND INDICATORS (CONT)
DEV RANGE
(Outer knob)
1. 5 kHz
5 kHz
15 kHz
Selects ac or dc coupling to the
VERT IN jack, AC is used for
general operation and DC is
primarily designed for calibration
purposes,
MOD MODE
(Outer knob)
Varies the dc balance of the FM
discriminator when making direct
coupled measurements, ‘The DC
BAL control affects the trace posi-
tion only wher the VERT IN switch
is in the INT position and the VERT
COUPLING switch is in the DC posi-
Pages 4-8 thru 4-11: Paragraph 4.7 thru 4,9, tion,
- ODM-1 control positions, Add: VERT COUPLING AC
CLASS CODE
APPROVED
SINGER
INSTRUMENTATION
LOS ANGELES, CALIF.
TITLE ADDENDUM
Model FM-2748/ODM-1
FORM NO. 160 IM 3-70 D-H
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ODM-1 RUNNING CHANGES, Continued
N а OMA CI.
Page 4-14: MEASUREMENT OF PEAK DEVIATION
Step d, Add: VERY COUPLING DC
DC BAL mid-range
|
|
Delete: Step h and add the following: | |
Set the VERT IN switch to EXT and verify that, without ап input signal, |
the trace is positioned on the graticule zero line, Vary the VERT CENTER |
control as necessary to position the trace, Set the VE2T IN switch to INT. |
Set the mainframe 10 MHz switch to IN and the frequency dials to 8. 000
MHz, Vary the DC BAL control to center the trace on the graticule zero
line. The trace position should not shift with changes in the DEV RANGE
Switch position, 2 He trace Ton Му USE Ne Y T z
E FEN Тар Sen Aa ry am
, 2 ) i ms
2
REVISED
CLASS СОВЕ
SINGER TITLE ADDENDUM
INSTRUMENTATION Model FM-2748 / ODM-1
LOS ANGELES, CALIF.
APPROVED
FORM NO. 160 ІМ 3-70 D-H
у hizi Ж
PD
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