Document text
President's Letter
Guarantee Certificate
Two Warranty Registration Certificates
| Certificate of Measured Performance
Operational Instructions
Installation Instructions.........
Front Illustration.
Immediate Operation .
Description of Tuner Displays.. ..
Back Panel Illustration. .
Description of Back Jack 2
Detailed Description of Scope.
Graticule and Trace Descriptions
Simplified Theory of Operation, , .
Block Diagram........++
Back Jack Panel Socket.
Final Test Check List
Mounting Template
Repacking Instructions
Spare Parts List
Spare Parts Packet
5174
» THE SEGUERRA cO. нс
71.07 WOODSIDE AVENUE
WOODSIDE, N.Y. 11377
(212) 651-4018
Dear Customer:
I would like to take this opportunity to personally thank you for becoming one
of the discerning individuals to own a Sequerra Model 1 FM Tuner, This instrument
represents a state of the art achievement in the Hi Fidelity industry, and embodies
in excess of 25,000 hours of engineering.
When completed, your Model 1 FM Tuner was individually measured for a
number of performance characteristics, The measurements are documented on a signed
Certificate of Performance, bearing the serial number of your individual Tuner.
Your Model 1 is covered by the Sequerra Five Year Warranty to meet the standard
specifications. 1 would like to call your attention to a number of exceptions to the
plan:
1, The Model 1 Tuner must be purchased only from a Franchised Dealer.
2. Any resale, or gift of the Model 1, requires the factory's acceptance of the
transfer of the unexpired Warranty.
3. The Company under no conditions would honor a Warranty if it does not
meet all of the criteria set forth in the Warranty Registration Certificate.
Although the Warranty ts in effect for five years, design and manufacture of
your Tuner is aimed at a useful life of at least ten years. Should your Model 1 ЕМ
Tuner require servicing, please contact only your Franchised Dealer, or the factory
directly, as the complexity of design renders it beyond the maintenance capabilities
of the untrained serviceman.
Our Company 1s dedicated to the development of extremely high quality
products, manufactured in very limited quantities. We anticipate that our products
will always be in short supply, therefore we offer to every purchaser of the Model 1
РМ Tuner, a preferential status vis-a-vis purchase of any of our future products, and
we anxiously solicit your inspection of our future products. As with any small
engineering based organization, we welcome suggestions and criticisms from our
customers, and hope to enter into such a dialogue with you.
We feel your Tuner will provide you with years of satisfying performance and
look forward to serving you again in the future.
y | Richard Sequerra
President
5174
INSTALLATION INSTRUCTIONS
In installing the Sequerra Model 1 FM Tuner, certain precautions must be observed, Follow the
Installation Instructions carefully, and in sequence. It is advised that you familiarize yourself thor-
oughly with the pushbutton displays and the back jack panel to appreciate the capabilities of the
tuner.
The following pages will impart an in-depth understanding. The page entitled Immediate Oper-
ation explains how to quickly work your tuner once it is properly installed, without thoroughly
understanding it. But to appreciate the full significance of the performance of the tuner, and to
make allowable adjustments to enhance the listening quality, a thorough understanding of its oper-
ations is imperative.
Warning: Please keep in mind that the warranty does not cover damage caused by
misuse, mishandling, insufficient ventilation, or excessive line voltage.
Placement - The tuner should not be placed near any source of heat, Allow а minimum of two
inches clearance above, behind, and below the tuner for ventilation.
Custom Installation — V you are installing the tuner іп an equipment cabinet, or behind a
panel, use the mounting template (near back of this manual) to make the required holes and cut:
outs.
Antenna — Choosing the proper antenna system is essential in order to minimize multipath
interference, Signal reflections from surrounding buildings, towers; or hills cause multipath inter-
ference, This phenomenon, similar to “ghosts” іп T V, produces distortion in the FM signals at the
antenna, No FM tuner can completely eliminate multipath interference, therefore careful selection
of an antenna is necessary in order to optimize performance of the system. The best FM reception is
obtained with a steerable or rotatable antenna. This holds true for either an indoor or outdoor an-
tenna used in conjunction with a rotor system. A comprehensive discussion of FM and FM system
problems (including antennas) is available from the Sequerra Company in booklet form. The price
of $1.00 covers handling and mailing.
Output — Connect the tuner to the pre-amp using the tuner's Output Fixed jacks on the back
panel, L & R stand for left and right. Be sure to connect left to left, and right to right, from tuner
to pre-amp.
Domestic Units — Make sure that local power is nominally 120 volts AC at 60 Hz as marked оп
the tuner's back panel.
Export Units — Power transformer is adjusted for a line input voltage of 220 to 240 volts, A
proper slow blow fuse has been installed.
Power Line — Unwind the power cord and plug it into an AC wall outlet.
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FRONT ILLUSTRATION
For Immediate operation (after properly following Installation Instructions) employ pushbuttons as shown by Function Arrows In this Illustration.
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IMMEDIATE OPERATION
To immediately operate the tuner (after it is properly connected and plugged in) without a
fundamental understanding of the various pushbutton functions, simply depress the lowest right-
hand pushbutton which bears the Sequerra "S", This will turn the set on. Turn the knob to tune in
your desired station. The station's frequency appears on the digital readout display above the word
Megahertz. An overcapacity of tuning is provided which permits the set to be tuned from 87.7 MHz
through 108.3 MHz. The Stereo Pilot will be illuminated if the tuned station is broadcasting а
stereo program. It is suggested that the following pushbuttons be employed
Muting: Inter-Station
Mode:Automatic
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DESCRIPTION OF TUNER DISPLAYS
The two vertical rows of six pushbuttons each operate the functions described on their adja-
cent display windows. The arrows when lit, pointing to the displays, will indicate which displays are
functioning. The upper four pushbuttons on the left are oscilloscope function selectors, They are
interdependent, and depressing any one of the four will release any other one of the four which was
previously depressed Е
A similar structure exists with the three muting pushbuttons on the top right side. The remain-
ing five pushbuttons are individually independent of any other, and when depressed will remain so
until individually released by depressing them again.
The following descriptions cover pushbutton functions. A more detailed analysis of the oscillo-
scope's traces are explored later.
Gema. The upper pushbutton, Display:Panoramic, displays all stations that are transmitting
Frame | 1 MHz above and below the tuned frequency. The vertical pips of the scope's trace
| represent stations which are broadcasting а signal above the ambient interstation noise level, which
is the base line. When tuned to a particular frequency, the station you are listening to will be cen-
і tered on the scope's graticule.
Samar) The second pushbutton on the left, Display:Tuning is used to properly tune the set.
“ines ) For proper tuning, the trace should be adjusted for the upper center of its path.
The third pushbutton, Display:Tuner Vector, displays the audio components on an
X-Y basis. This vector exhibits the left and right stereo channels along a perpendic-
ular axis, It is used in checking the separation and phase characteristics of stereo program material
‘The wider the angle, the greater the separation. The higher the trace, the stronger the signal, А
vertical line indicates no separation (as a centrally positioned announcer, or monophonic trans-
mission)
md
Zona, | The fourth pushbutton, Display: Ext. Vector, displays separation and phase charac-
LEE Tero) teristics of any stereo or four-channel programming. To be functional, proper con-
nections have to be made to the External Vector Input section in the back panel. Stereo program
material is displayed identically to Display: Tuner Vector. Four-channel program material is dis-
played оп 4-legs of ап “Х"" shaped trace, indicating the corners of front, rear, left, right. The separa-
tion, phase, and amplitude of each leg of quad programming can be observed.
С) The fifth pushbutton, Separation: Maximum-Hi Blend, controls the separation of the
(нее J high frequencies in stereo broadcasting. It is used to eliminate some noise under
difficult listening conditions. Ordinarily have it set to Maximum for best spatial and directional
detinition of listening material.
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When encountering excessive interference or background noise, switch the Separation to Hi
Blend. This position blends the high frequencies of the left and right channels together providing a
good compromise, between moderate separation and moderate suppression, of out-of-phase noise
and distortion, This permits you to maintain full frequency response, differing from conventional
iate noise by reducing high frequency response. Note: If the Hi Blend
Position does not satisfactorily reduce stereo noise, switching the Mode display function from Auto-
matic to Mono (fourth pushbutton on right) completely eliminates all stereo noise, but the program
will be received monophonically.
[===] тег) The bottom pushbutton on the left, Dolby:Off-On, interposes or removes a Dolby
сә) Type B decoder in the output audio lines, affording you the benefits of the Dolby
noise reduction system when the station is transmitting Dolby.
‘The upper three pushbuttons on the right are for muting functions. They are interrelated and
depressing any one cancels out the other two. The muting level is set by an adjustment on the back
jack panel of the set (refer to Back Panel Muting Instructions).
mamac | Depressing the top pushbutton, Muting:Off, cancels out all muting functions. In this
= mode all inter-station noise is heard, Although most people find inter-station noise
objectionable (with the high performance of the Sequerra Tuner this noise appears accentuated), it
is useful in giving you a truer understanding of what is really happening throughout the entire
broadcast band. It permits you to hear broadcasts, with a very weak signal strength, that are
beneath the preset muting level,
The second pushbutton down, Muting:Inter-Station, mutes all undesired noise
(beneath the preset muting level) while tuning between stations,
[руге] The third pushbutton, Muting:Inter-Stereo, will mute not only inter-station noise
sven неко Ј but also monophonic broadcasts, allowing you to receive only stereo broadcasts.
There is another muting system designed into the tuner which is non-adjustable. (The Muting
Level adjustment is on the Back Jack Panel). It has to do with off-center tuning noise. To best
understand it, consider the Display: Tuning pattern. When a station is properly tuned the trace is on
the center line. As the trace approaches and goes down the sides of the tuning pattern (off center
frequency) it is automatically muted, This muting circuit operates when either Inter-Station or
Inter-Stereo muting is incorporated. It is by-passed when Muting:Off is engaged.
Aw | The fourth pushbutton on the right, Mode:Automatic-Mono, in the automatic posi-
= tion, automatically senses whether the received signal is stereo or mono, and chan-
nels the signal through the proper circuitry. Consequently it is usually kept in the Automatic posi-
tion, The Stereo Pilot will light when a stereo program is being received. When a mono program is
being received the set is designed to bypass the multiplex decoding circuitry, thus eliminating any
Possible stereo noise. With the Mode pushbutton depressed to Mono, it will receive stereo programs
monophonically. This is useful in eliminating all stereo noises when stereo programming is being
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received under difficult conditions, and те Separation:Hi Blend pushbutton does not sufficiently
eliminate undesirable noise. Of course, in this mode, the program will be heard in mono.
It is also suggested to have the Mode in Mono when listening to a monophonic program, to
eliminate any possibility of an unwanted signal triggering the Stereo Pilot. This would direct the
programmed material through the multiplex decoder, and consequently pick up any concommitant
stereo noise. If this occurs, the Stereo Pilot will flick on.
TONE
The Panel:Normal-Dim, pushbutton merely changes the intensity of the illumination
of the display screens and oscilloscope.
The Power:On pushbutton switches the tuner on and off. It is marked with the
Sequerra "5", the only identification on the front of the set, which serves for easily
locating the power button when the set is іп its "blackout" position. In the On position it lights all
functional displays.
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BACK JACK PANEL
FOCUS INTENSITY ~aoust ror verr] f L _OUTPUT_ R
@ DIM SPOT ON EXT. VECTOR Q Q
SCOPE
VERT. HOR.
eo o
CENTERING
EXT. VECTOR
INPUT
105-135V AC
50-60 Hz
Qo
SERIAL NUMBER
ANTENNA CONNECTION TERMINALS
Connect antenna leads to appropriate terminals (match impedances)
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DESCRIPTION OF BACK JACK PANEL
The back Jack Panel has four inputs, five outputs, an accessory socket, scope and pan adjust-
ments, a Dolby converter, a fuse, the line cord, and the serial number. Following is a description of
their proper use.
Fuse — For U.S.A. а 1-атр, slow-blow, standard ЗАС cartridge type fuse is used, For non-
domestic use, the proper fuse for the country of use has been installed.
Power Line Cord — Plug only into AC outlet. In U.S.A. 115V AC 50-60 Hz. Proper operation
will be had from 105-135V. European tuners are adjusted for 220V AC, 50 Hz (refer to Export
Units in Installation Instructions section)
When taking the tuner from one country to another, take it only to an authorized dealer in the.
country of use for proper conversion, Servicing by user or unauthorized personnel will void war-
ranty.
Output Fixed — Use this output to plug into stereo pre-amplifier. Delivers 1 volt RMS for
100% modulation from an internal impedance of 600 ohms into an open circuit or high impedance
load. Can deliver % volt into 600 ohm external load. Can Drive as much as 100 feet of 33 picotarad
cable on each output leg without causing any degeneration of signal.
Output Level — This output consists of а 5,000 ohm pot connected across the output of the
Fixed Output. It has а varying internal impedance that cannot exceed 2800 ohms. It can be used to
drive short standard cables into high impedance inputs.
External Vector Input — input for four-channel signal source for scope display through the
tuner's four-channel matrix circuit. Depress the Display:External Vector pushbutton, Also may be
used to monitor external stereo sources. Use Front, |. & R inputs.
Scope — АН Sequerra tuners are properly adjusted before leaving the factory, If for any reason
the scope's trace needs adjusting, follow the proper procedure:
1. Remove ай! inputs.
2. With small screw driver set the Scope Intensity adjustment to full counterclockwise
position.
3. Set scope's Focus, Vertical, and Horizontal adjustments to center position.
4. Switch power on. Allow a minimum of 1 minute for tube to completely warm up, It is
better to wait 15 minutes to allow the tuner to stabilize at full operating temperature,
thus avoiding any possible drift effect.
5. Depress the Display:External Vector pushbutton.
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6. Slowly шт Intensity Adjustment Clockwise until a very dim (barely visible) trace
appears on the scope's screen. Ìt is important to keep this trace extremely dim, Auto-
matic brightening circuitry will adjust the intensity as required during performance. А
bright spot will cause burn-in and shorten the oscilloscope tube's life. Such use will void
the warranty. Now adjust the Focus control until the scope's trace becomes the smallest
Possible dot, Again adjust the Intensity control for the dimmest possible dot. The
Vertical and Horizontal controls are used to bring the dot into the exact certer of the
scope, To properly center the dot, observe the tube exactly dead-on-center from the
front to avoid any parallex. Use the center vertical line with its center cross mark to
locate the exact center.
Muting Level — This adjustment is used to tune out all signals having noise level which is
unacceptable to you.
1. Depress the Muting:Off pushbutton.
2. Tune ina station which you consider to be on the threshold of having an unacceptable
noise level.
3. Depress the Muting:Inter-Station pushbutton.
4. Adjust the Muting Level control to the point where that station just mutes out,
Now any station with a noise level equal to, or more than the station just used will be muted
out as you tune through the FM band. This muting level applies to both the Muting:Inter-Station,
and Muting:Inter-Stereo pushbuttons. The potentiometer used for the Muting Level control has a
range of З microvolts to 30 microvolts.
Panoramic Sweep — The electronics for the panoramic display function is optional and is not
included in all sets. Again, remember that all tuners are adjusted before leaving the factory. But, in
the event the panoramic trace needs adjustment, follow these procedures. This task can be made
simpler with a proper understanding of what's on the screen. The important thing to understand is:
1. The vertical lines on the graticule are designed to be 400 Hz apart.
2. The FCC frequency assignments to alternate (primary) stations are 400 Hz apart, This
spaces the adjacent stations midway (200 Hz) between the alternates
In relative strong signal areas, it may be advantageous to remove the antenna leads and replace
‘them with a small piece of wire. Although the pips will not be as strong, they may be more easily
adjustable.
To Adjust Centering:
1. Depress the Display: Panoramic pushbutton and tune for a primary station by centering а
large pip.
2. Now depress the Display:Tuning pushbutton for more accurate center tuning and checking
the station frequency on the di Il readout.
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3. Now depress the Display:Panoramic button again. Do not touch the tuning knob, and if the
station’s pip is off center, center the pip by adjusting the Panoramic Sweep Center control,
To Adjust Width:
Depress the Display:Panoramic pushbutton.
Select a portion of the broadcast band where the primary alternate stations are broad-
casting.
3. Identify the pips by using the digital readout (switch momentarily to Display: Tuning for
more accurate tuning).
4. Then by using the Width adjustment control, align the pips of the primary alternate stations
with the vertical lines on the graticule.
б
The Width adjustment may move the pips off center, in which case go back and adjust the
centering. You may have to go back and forth several times before attaining optimum alignment.
The final adjustment may not fall exactly on the lines, as the scope displays are approximate and
not designed for hairline perfection. A highly usable compromise is easily achieved.
25 Microsecond Dolby — The present U.S. A. Dolby standard is for 75 microsecond de-
emphasis. European sets are delivered to operate at 50 microsecond de-emphasis, which is the
European standard. Conversion from one standard to the other is a simple matter, but should be
done only by a Franchised Dealer.
Presently in the U.S.A. there are considerations by the FCC of permitting and/or standardizing
оп 25 microsécond operation. In instances of 25 microsecond broadcasting all that is required for
the tuner to be properly converted is to insert a shorting plug into the 25 Microsecond Dolby jack
Detector Output — This output supplies a signal, before de-emphasizing, directly from the
output of the FM detector prior to multiplex decoding. This output has application to four-channel
demodulation, broadcast testing, and other special purposes.
Accessory — When not in use, the shorting plug supplied with the tuner must be properly in
the socket. If it is loose or absent, the digital readout will read either 189.3 MHz or below 88.0
MHz, and turning the tuning knob will not effect these readings.
The Accessory jack is used to interface the tuner with various accessories, i.e. the optional
remote pushbutton tuning assembly.
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10
DETAILED DESCRIPTION OF SCOPE
А thorough understanding of the information shown by the oscilloscope’s trace will give an
appreciation of what is being broadcast plus the quality of the broadcast. This presents an оррог-
tunity to make allowable adjustments, with the tuner and antenna, to achieve the best possible
reception of receivable programs. All scope measurements and trace information are approximate.
They are used to establish references and are not designed for hairline accuracy.
The cathode ray display tube requires greater warm-up time (about 30 seconds) than the dis-
plays before the trace becomes visible.
The oscilloscope display dims automatically whenever the trace reduces to а "дог" (at low or
no audio signal levels). This automatic dimming action extends the life of the cathode ray tube and
reduces the possibility of accidently burning the screen phosphors,
Panoramic — In this mode the scdpe displays all stations broadcasting within а 2 MHz spec-
trum. (1 MHz each side of the tuned frequency). The height of the pips indicate the relative signal
strength of the stations. The noticeable motion of the pips is the result of the material being broad-
casted plus multipath. The pan response is flat at the center although not across the entire 2 MHz.
This will cause some slight diminis of the height of the pips as they are tuned across the band
away from center frequency. The height of the pips indicate the relative signal strength of the
stations and corresponds to the approximate height of the trace of the tuning display (second push-
button). This is just an approximate height match as the center vertical line on the pan display has a
dynamic range of approximately 100dB. This is the result of some slight compression at the top and
displacement at the bottom. The vertical center line on the graticule delineates the center fre-
quency. The two vertical lines on either side of the center line are spaced at intervals of 400 kHz.
This spacing corresponds to the FCC spacing of alternate stations on the bandwidth. Adjacent
stations fall midway between the alternates at 200 kHz spacings, and when the set is tuned with a
primary station on the center line, the alternate stations will be on the vertical lines, while the ad-
jacent stations will fall between the lines.
A three-pointed trace represents a station with an SCA subcarrier. Some FM stations simul-
taneously broadcast a Subsidiary Communications Authority (SCA) signal on the same carrier fre-
quency as their regular broadcast. SCA broadcasts are privately sold to commercial users such as
restaurants, offices, stores, etc., and contain no commercial advertising.
NOTE: Ail spectrum analyzers produce а varying number of ambiguous and erroneous displays.
The Panoramic Display in the Model 1 Tuner is no exception. The types of erroneous displays that
you may expect are listed as follows
|. Image Responses: Al stations having a signal strength of greater than 5000 microvolts will
produce an image response in the display precisely 4.8 MHz above the station.
2. Spurious Responses: These responses, in this tuner, are attributed mainly to the dynamic range
limitations of the system. The dynamic range upper threshold is 100,000 microvolts. Signal
input greater than that produces significant displacement of the base line as well as a series of
side band modulation products.
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п
3. Cross modulation products due to the out of band signals i.e., excessively strong television
signals below the FM band and excessively strong aircraft signals above the FM band may
produce spurious responses.
4. Clandestine FM transmitters i.e., bugging devices, radiation from other FM tuners, and other
sources of electromagnetic radiation within the band will be read as responses in the Panoramic
Display.
Tuning — The oscilloscope trace follows an approximate trapezoid. Spinning the tuning knob
fast will give an idea of the band pass pattern. Signal strength is indicated by the relative height of
the trace above the inter-station noise level (the lower and heavier horizontal path of the trace), The
center graticule line displays a dynamic range of approximately 110 dB. It is divided into decades,
These callouts are not meant to be exact but are only approximate, They're given for relative dis-
cernment of signal strength.
Modulation (or carrier deviation) is displayed by the instantaneous horizontal expansion and
contraction of the trace when tuned at the upper center. Loud passages are indicated by wide
traces, while softer passages are seen as proportionally shorter traces. Over-modulation by the trans-
mitter is displayed as an excessively wide trace extending beyond the two vertical lines on either
side of the center line. These vertical lines represent the instantaneous peak deviation of 75 kHz
either side of the center line.
Weak distant stations can be seen on the scope although they may be below the tuner's set
muting threshold. Adjusting antenna direction will frequently increase signal strength sufficiently to
pull the signal out of the inter-station noise level and give good reception. In extreme cases, a very
weak signal can be made audible by setting Muting to Off
A station broadcasting an SCA sideband can also be seen with the Tuning Display. It is
detected by an inward reach of the trace when the trace is at the upper portion of either side of the
trace pattern,
Adjusting Antenna Direction For Minimum Multipath — The tuning display serves the jm-
portant function by showing when the antenna is pointed to best possible direction to minimize
multipath, Multipath interference, similar to a "ghost" in T V pictures, produces distortion in the
РМ signals at the receiving antenna, This results in a distorted sound. To minimize multipath inter-
ference, and obtain the best reception from each station, adjust the antenna to the direction which
results in the smoothest and most horizontal trace. This direction frequently may not be the same
as the direction for the strongest signal (maximum vertical deflection)
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12
PANORAMIC
GRATICULE DESCIRPTIONS
100 dB |
1. kHz +a | Ideal Dynamic Range
Actual Dynamic Range due to
2 MHz compression at top and dis-
Frequency Spectrum placement at bottom
Е 517
PANORAMIC
DESCRIPTION OF PIPS
M
A, Tuned in station on
center frequency.
Same broadcast received by 2 different antenna 2 Stations with same signal
systems. strength
B. Alternate station 400 А. Rabbit ear FM antenna A. Monaural
kHz off center frequency B. Outdoor roof antenna (note overload). This was B, Stereophonic
С, Altemate station 800 close line-of-sight developing 0.3V input to tuner. С. Bend at top of pip
kHz off center frequency . alates ideo HORT
Note: 3-pointed pip indicates
station simultaneously broad-
casting SCA.
D. Adjacent station 200kHz
off center frequency .
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*
TUNING
Graticule Description Trace Description
7-Noise Level
б---{----: Noise Density
75 kHz Spacings
Typical
(complete cycle)
Trace Pattem
For Dynamic Range see Panoramic Graticule Description
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ч
TUNING
TRACE DESCRIPTIONS
I
Soft Passàges
Loud Passages
(Full Modulation )
Overmodulation by
broadcaster
(causes distortion)
Station not properly tuned
|
Off-Tuned trace
g (Showing SCA sub-
carrier)
Weak Station
Station with Low Amplitude
Station with High Amplitude
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TUNING MULTIPATH
Ideal Trace
(No Multipath)
|
Е =
Multipath progressively worse (A trhough Е). The long
gentle curve of A 1s preferable to B, etc. In tuning to
eliminate or minimize multipath, rotate your antenna
E
to get the smoothest trace. This will be your best
listening position, even 1f it has less amplitude than
in other positions.
ц
Very severe multipath
(partial cancelation of signal)
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TUNER VECTOR
— nr
Left Channel Only
TRACE DESCRIPTION
A
M
Right Channel Only
No Separation Between
Channels (Monophonic)
2
L-R Out.of phase Stereo
M
Га
A
_. Little Separation Between
© Channels (Such as Centrally
Placed Soloist)
Maximum Separation Between
Channels
Right
Improper Balance to the
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EXTERNAL VECTOR
4 CHANNEL TRACE DESCRIPTION
CONS
Front Left Channel Only Front Right Channel Only
Rear Right Channel Only
К
— Stereo LGR Front Inputs Only.
© (Same as Stereo for Tuning
Vector) Maximum Separation
Stereo L&R Rear Inputs Only,
Maximum Separation
Rear Left Channel Only
7 Channel - Maximum
Separation Between Channels
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SIMPLIFIED THEORY OF OPERATION
The Model 1 FM Tuner is a superheterodyne frequency modulation receiver consisting of two
RF Subsystems, a Stereo Multiplex Decoder System, a Dolby Noise Reduction System, an In-
strument Type X-Y Oscilloscope, а Frequency Counter, and a small Analog Computer that derives
all of the Audio Displays. The Моде! 1 FM Tuner can be most easily understood in terms of the
functions of the individual modules it contains.
The following modules are in the Model 1 Tuner:
Front End
FM IF Filter
FM Limiter
4, FM Detector
Multiplex Decoder
Dolby Noise Reducing System
Frequency Counter.
Four Channel Display Computer.
Panoramic Sweep Generator Oscillator Mixer
10. Panoramic IF
11. Panoramic Log Detector
12. X-Y Oscilloscope
13. A Number of Regulated Power Supplies
14. Visual Display System
эю
ооло
NOTE: These units are defined by similar key numbers in the block diagram.
1. FRONT END
The Front End performs three basic functions.
1. It provides the initial RF selectivity by utilizing a differentially coupled 3 pole amplifier.
2. With its internal Local Oscillator it mixes the selected RF frequency to derive the IF fre-
quency which is used to drive both the FM IF and the Panoramic IF.
3, It provides the signal to drive the Frequency Counter.
2. FMIF FILTER
The IF Filter has the function of supplying sufficient selectivity to separate stations that are at
least 400 Hz apart on the FM dial. The FM IF also supplies the AM signal which derives the
last decade of the vertical display in the tuning mode. B
3. FM LIMITER
The FM Limiter provides a means of removing all of the AM noise produced from the selected
signal, leaving only the zero axis crossing information to be fed to the FM Detector, The FM
Limiter also supplies the first five decades of vertical information from the Tuning Display.
4. FM DETECTOR
The FM Travis-Smith Detector takes the information contained on the zero axis crossing from
the Limiter and converts that time displacement into an audio signal. Its output drives the
Multiplex Decoder, and the horizontal axis of the oscilloscope in the Tuning Display.
5. MULTIPLEX DECODER
The input circuit to the Multiplex Decoder is used to separate the 19 KHz pilot and to remove
the 67 KHz (SCA) signal from the composite stereo signal. This is a uniquely designed filter
system which precisely controls the phase amplitude relationships of both L+R signal, and the
L—R signal. This system can be termed a quasi-vestigial side band processing circuit. At this
point, the separate 19 KHz signal is fed into a frequency doubler which is used to phase lock
the free running 38 KHz constant amplitude oscillator.
From the 38 kHz phase synchronized oscillator, the multiplex peak decoder switching system
is driven. The peak detection system is the one that permits the least possible phase error in
the demodulation process and can be properly called a push-pull peak detector.
The output of the multiplex system is fed into the output filter system which performs the
following functions: First it inserts the normal 75 usec. (50 usec. available on special order)
de-emphasis curve; then it adds to it the roll off whose inflection point is around 23 kHz; an
additional notching filter is inserted after this to remove the remaining components of the 38
kHz oscillator. This system is capable, with a saturating signal, of a signal to noise ratio of
greater than 70 dB below peak levels,
в. DOLBY
The Dolby demodulator performs the function of the automatic frequency correction of a
Dolby encoded signal, It is only used when the station is broadcasting in a Dolby encoded
mode.
7. FREQUENCY COUNTER
The Frequency Counter displays the frequency of the station that the set is tuned to. It
operates in the following manner: This counter has been designed to count to 200. In its reset
arithmetic ít is always set to 189.3. A signal from the local oscillator in the Front End is fed
into the input of the counter. Since the local oscillator's frequency is 10.7 MHz higher than
the stations frequency, the counter in its scaling will read the stations frequency. This counter
ше а | MHz crystal as its time base, and has an accuracy of + 100 Hz reference to the stations
frequency,
5174
21
NOTE: All counters have a potential ambiguity of reading in the last digit. This is defined as the
readable resolution of the counter. As the stations frequencies are changed by tuning the knob, it is
possible in an off station mode to see a reading ambiguity in the last digit.
8. FOUR CHANNEL DISPLAY COMPUTER
The Four Channel Display Computer is а device for separating the phase amplitude com-
ponents of either a left or right stereo signal or an externally applied stereo, or four channel
signal. This system displays in the Four Channel quadrants, the phase amplitude characteristics
of the input signals as compared to any of the other 3 input signals. All vectors have the center
of the oscilloscope as their origin (see illustrations of trace descriptions).
9. PANORAMIC SUBSYSTEMS
10.
41, The Panoramic Subsystem consists of a Sweep Generator which is used to both drive the
Horizontal Axis of the oscilloscope in the Panoramic Mode, and to change the frequency of
the panoramic local oscillator + 1 MHz. The panoramic mixer uses the panoramic oscillator
sweeping frequency and mixes it with the output of the mixer in the front end to derive the
2.4 MHz Panoramic IF Frequency. The Panoramic IF provides sufficient selectivity to separate
for visual display, stations on the dail that are less than 200 kHz apart. The Panoramic Log
Detector provides the 6 decades of vertical display on the oscilloscope in the Panoramic Mode.
12. X-Y OSCILLOSCOPE
The X-Y Oscilloscope utilizes an instrument type 4% inch flat faced tube and has an approxi-
mate sensitivity of .5 RMS volts per inch on either axis, It has a band width of approximately
100 kHz on both axis, In addition the automatic dimming circuit is activated in 2 modes,
either signal amplitude or preset for the mono-audio display.
13. REGULATED POWER SUPPLIES
This power supply system provides the necessary regulated voltages to all the previous systems.
It is short circuit proof, and can be adjusted for either 120 or 240 volt operation,
14. VISUAL DISPLAY SYSTEM
The Model 1 Tuner has a very complex Visual Display System which is driven by the 12 volt
AC power system. It is used to illuminate the main screen (see illustration), to illuminate the 3
individual graticule systems (refer to Scope Display), and to light the Stereo Pilot and the
Megahertz word. This system is individually fused and the fuse is located on the step shelf of
the power supply chassis.
5174
Её
зоол ANTENNA
MODEL | FM TUNER-SIMPLIFIED BLOCK DIAGRAM
AUDIO OUTPUTS
* 5 5
LEFT
TRAVIS-SMITH
DETECTOR MULTIPLEX росву
ану төнт
COUNTER
нн: CLOCK
40017
то
PAN SWEEP
LOCAL OSC MIXER
(2M TO AIME
тө 2.амн:
STEREO
PILOT
_]
еа конта «»сзе-ө
TUNING POT
TAN TO 32V
POWER
TRANSFORMER
P 120/240
50-вонт
EXT INPUTS
P awpLirier ©
AMPLIFIER ©
oer
ouTPuT
"
VERTICAL
5174
REAR VIEW OF SOCKET
on BACK JACK PANEL
(Enlarged 8 Times)
1. +15 Volt Supply
2. -15 Volt Supply
3. Tuning Bias Supply
4. Tuning Potentiometer Voltage Output
5. Front End Tuning Voltage Input
6. Front End Tuning Ground
7. Chassis Ground
8. n.c.
9.. 25 рес Dolby
10. Detector Signal
Internal
Jumper (to
be cut
"when
using -
remote
tuning)
24
—
CABINET MOUNTING
INSTRUCTIONS & TEMPLATE
REMOVE FOR USE
ae ж
CABINET MOUNTING INSTRUCTIONS
(Read and understand thoroughly before doing any cutting)
This sheet is designed for those wishing to house the tuner inside a cabinet
with only the face of the tuner positioned to be visible through the cabinet's
front paneling,
For cabinet installation of The Sequerra Model 1 FM Tuner, it is essential to
provide sufficient ventilation. This will assure trouble free operation and long
life. The supporting shelf inside the cabinet should be at least 3/4", thick.
The internal cabinet area housing the tuner should be a minimum of 18" wide
by 9" high by 144" deep. Leave the back of the cabinet open above and below
the supporting shelf to assure good ventilation. There should be no heat pro-
ducing equipment directly under the tuner's supporting shelf. If your system
is such that heat producing equipment must be under the tuner, a small air
circulation fan is mandatory.
On the other side of this sheet the Cabinet Mounting Template is printed. It is
used to establish the areas to be drilled and cut out of both the front panel and
the supporting shelf. The Cabinet Mounting Template consists of two parts:
(1) "Part -Front Panel Cutout Template, (2) "Part B"--Inside Shelf Cutout
Template. Line "A" is common to both Parts. "Part A" will be used to establish
the cutout in the front panel of the cabinet through which the tuner will fit. "Part
B" will be used to establish the anchoring holes and the ventilation holes on the
shelf on which the tuner will rest.
1, With a scissors, cut the template along Line
Also cut out the two notches "D" from "Part B".
separating the two Parts.
2, Place the "Part A" Template inside the cabinet, flat up against the back of
the cabinet's vertical front panel. It should be placed on the inside exactly
where the cutout will be in the panel, through which the tuner will fit. Make
sure that Line "A" (which is the bottom of "Part A") is flush with the top sur-
face of the shelf on which the tuner will rest. Hold the Template in this posi-
tion and with a pointed instrument mark the rear surface of the cabinet's panel
through the three alignment points "B" of the Template.
3. Remove the Template and drill 1/16" holes through the cabinet's panel at
the alignment point marks. Make sure the drill is held perpendicular to the
panel and parallel to the supporting shelf.
4. Now, place the "Part A" Template on the front outside surface of the cabi-
net, keeping Line "A" as the bottom, and align the points "B" with the 1/16"
holes drilled through the cabinet's panel. With the Template in this position,
mark the four corners, points "C", on the front panel of the cabinet with а
pointed instrument. Remove the Template and with a straight edge connect
the corner points. (It is through this rectangular area that the tuner will be
positioned іп the cabinet.) Saw out the rectangular opening. The sawing should
be done carefully from the front of the cabinet to avoid chipping or marring the
cabinet's finish around the opening. When properly completed, the bottom
edge of the rectangular panel opening should be flush with the top of the-sup-
porting shelf.
5. Place the "Part B" Template inside the cabinet. It should Це flat on the
supporting shelf. The notches "D", which were cut out of the Template, will
permit the Line "A" edge to be placed into the rectangular cutout of the cabi-
net's panel. The Line "A" edge should be positioned flush with the bottom
front surface edge (the outside edge) of the cabinet's cutout.
6. With the Template tn this position, use a pointed instrument to mark the
surface of the cabinet's shelf through the four points "E" of the Template. Re-
move the Template and drill 1/4" vertical holes into the shelf of the cabinet
at the four "E" point marks. These holes will be used to anchor the tuner to
the shelf.
7. Again place the "Part B" Template into the cabinet as per step 5. With a
pointed instrument, mark the corners of the two rectangular ventilation holes,
indicated on the Template, onto the shelf of the cabinet. Remove the Template
and with a straight edge connect the corner points of each of the two ventila-
tion holes. Then saw out the two ventilation holes from the shelf. These
holes will permit air circulation and prevent heat build-up.
8. Remove the four feet from the tuner by unscrewing them. The feet are not
used in a cabinet installation. Insert the tuner through the front of the rec-
tangular panel opening of the cabinet. To anchor the tuner to the shelf use
the four #9 X 32 Phillips head screw bolts and the four +8 flat washers and
the four #8 lock washers supplied in the spare parts pouch. Anchor the tuner
to the cabinet by passing the bolts up through the "E" holes and screwing them
into the feet-holes of the tuner. The lock washers should be sandwiched be-
tween the heads of the screw bolts and the flat washers. When the bolts are
tightened, the flat washers should be pressing up against the bottom of the
cabinet's supporting shelf. NOTE:The bolts should not penetrate the tuner
more than 1/2" (length of bolt should not exceed thickness of shelf plus 172").
ә
CABINET MOUNTING TEMPLATE
ANC.
FRONT PANEL CUTOUT TEMPLATE
Mass THREE кот FONTE чи ON BACK OF CABINET FANEL (3)
Dit тиме 1/16 HOLES THROUGH RACK OF HAMEL AT "P MARES (2)
Е
m
LEA шан эти OUTSIDE EDGE CF PANEL CUTOUT (8
ме. LL sine
INSIDE SHELF CUTOUT TEMPLATE.
Mur
буе
on ts sheet commapen to
emer ee she rae)
SAVE ALL PACKING CARTONS AND MATERIALS
The SEQUERRA COMPANY takes every precaution in the manufacturing, testing, and
packaging of its equipment to insure long life and to preclude servicing. However, if it
ever becomes necessary to ship this unit, following the procedures outlined below will
afford protection against damage in shipment.
1. Use original carton and filler material properly packaged, sealed, and
labeled.
2. If original carton is unavailable, use a carton of sufficient strength and
size. It should be firmly packed with plenty of padding between the
unit and all surfaces of the carton.
3. For your protection, select а reputable carrier and insure shipment for
its full value.
THE SEQUERRA COMPANY, ING
woonsine А) WOODSIDE, NY 1377
ПАСВАМ - INSTRUCTIONS
Ве sure to save shipping materials and
shown when shipping.
repack tuner as з!
PACKING & REPACKING
Di n С
5174
SPARE PARTS LIST
The spare parts are found in а packet following this
page. The packet contains:
One bayonet #1815 bulb mounted in the reflectors behind
the display windows.
For Domestic (110-120 VAC) Units:
One 1 Amp slow-blow Fuse
For Export (220-240 VAC) Units:
One 1/2 Amp slow-Blow Fuse
NOTE: This fuse is positioned in the Back Jack Panel.
One 5 Amp filament fuse positioned on the shelf of the
power supply, protects display lights.
Four 6-32 1/4" flat head, black oxide Phillips screws
used in securing tuner covers.
е
THE SEQUERRA COMPANY, INC.
7-07 WOODSIDE AVENUE, WOODSIDE, N.Y. 1377
THE SEGUERRA MODEL! FM TUNER
SERIAL NUMBER...
2] Коа
FIVE YEAR WARRANTY
The Sequerra Company, Inc. warrants to the original using purchaser that The
Sequerra Model | FM Tuner shall be free from defects in workmanship and mate-
tials under normal and proper use for a period of five years from the date of
purchase.
STATEMENTS OF WARRANTY
А. Warranty registration shall become valid only when both the authorized retail
franchised dealer selling the tuner and the customer have filled out their respec
Ji the Warranty Registration Certificates, and the Factory's Copy of
‘has been mailed to The Sequerra Company within ten days of orig
ог replace all detective parts returned within
years (сот date of purchase at no charge to the original owner for either
bor or materials.
C. All defective equipment, parts, or modules shall be returned to The Sequerra
Company ог its authorized service station, shipping and handling prepaid for both
directions, only with the expressed written authorization from the Company.
D. he Sequera Company reserves conduct an inspection ol the дие
tive parts and materials and. to its satisfaction that the equipment has not
been repaired, altered, or modified by any unauthorized personnel.
E The oscilloscope tube and incandescent lamps are covered only for a period of
one уем.
F. АН replacement parts supplied under this warranty shall carry the unexpired
portion ofthe original warranty on a pro гиз basis
6. The warranty i ransterabl only with the expressed written authorization Irom
The Seguerra Company.
H. The Sequerra Company reserves the right to modify, change, or redesign with-
the Model 1 in whole or in part at any time without prior notification
егег is not obligated to incorporate any possible Iure changes
medications into any Sequerra Model 1 Tuner inthe field.
This warranty states Tally and expressly, and in lieu of all other warranties
implied or expressed by any other party, the total obligation of The Sequerra
Company.
owner
ADDRESS
ATE OF PURCHASE
бєлїн
ADDRESS
‘AUTHORIZED SIGNATURE
THE SEGUERRA COMPANY, INC.
FIVE YEAR WARRANTY
REGISTRATION CERTIFICATE
FOR
THE SEGUERRA MODEL! FM TUNER
To register your Five Year Warranty, please fill in the requested information
below, on both copies of the Registration Certificates, Mail one certificate to
The Sequerra Company and the other to the franchised dealer where the tuner
was purchased. Stamped envelopes are enclosed for your convenience, A
delay of more than ten days will void the warranty.
DATE OF PURCHASE
ORIGINAL PURCHASER (PLEASE PRINT)
AOORESS
ату SUE т»
DEALER
ADORESS
oy STATE E
‘SIGNATURE OF PURCHASER
THE SEGUERRA COMPANY, INC.
eee
1-Factory's Сору
5174
TEST MEASUREMENTS
Tuner Serial Ко...
date_
1. Volume Sensitivity (2 dB)
2. Quieting Mono
3. Quieting Stereo
5. THD Stereo 1000 uV tnput
6, Stereo Separation
8. Capture Ratio
7. Selectivity 20-98 interference Freq, + Us
70 98 Sig. Diff. to SAS
Hb ael
1-9 ил
a es ЕР
60 dB t
70 dB im
Ultimate S/N `7-2> e)
30 dB
Ultimate S/N
4. THD Mono 1000 uV input 30 Hz of ў
400 Hz 2 Cs
z ТТТ
No de-emphasis @ detector output 15 kHz Ж.-С,
100Hz EN,
Left to Right
Cod
30 dB о;
50 dB
o 73
9. Minimum Discernable Signal Panoramic
(Original on file at the Sequerra Gompany)
ый.
— TESTER