Hammarlund SP-600-JX-17 Operating instructions

.----------------- * ------------- --....".
T.O. 31R2-4·18-2
(Formerly AN 16-45-434)
HANDBOOK
SERVICE INSTRUCTIONS
RADIO RECEIVER
MODEL SP-600-JX-17
(HAMMARLUND)
LATEST REVISED PAGES SUPERSEDE
THE SAME PAGES OF PREVIOUS DATE
Insert revised pages into basic
publication. Destroy superseded pages.
PUBLISHED UNDER AUTHOR'ITY OF THE SECRETARY OF THE AIR FORCE
_11- ................. ---------------.,.-- * ----:....----------------..!!!
A~,;fNunns ~ Klmmler, Inc., Cincinnati, Ohl0,700, 9-63--ftEPRINT
30 JUNE 1953
REVISED 10 SEPTEMBER 1955

T.O. 31R2-4-18-2
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10 September 1955
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Revised 10 September 1955

Section
AN 16-45-434
TABLE OF CONTENTS
Table of Contents
Page
I DESCRIPTION AND LEADING PARTICULARS .. _ .. _. . . . . . . . 1
1-1. General. ............................................. 1
1-5. Purpose and Limitations. .............................. 1
1-8. Leading Particulars. ................................... 2
1-19.
Pertinent Data ..... ................................... 5
1-32.
Operating and Adjustment Controls. .................... 8
II TEST EQUIPMENT AND SPECIAL TOOLS. _. . . . . . . . . . . . . . . . . 10
2-1. Test Equipment. ...................................... 10
2-3. Special Tools 10
2-5. Cable Fabrication 10
III PREPARATION FOR USE AND RESHIPMENT 11
3-1. Preparation for Use 11
3-3. Setting up Receiver 11
3-8. Storage. ............................................. 12
IV THEORY OF OPERATION 13
4-1. General System Operation 13
4-4. Receiver Functional Operation. ......................... 16
4-14. Simplified Circuit Theory. ............................. 18
4-96.
Functional Operation of Mechanical Components 38
V
OPERATIONAL AND ORGANIZATIONAL MAINTENANCE. .39
5-1. General. ............................................. 39
5-6. System Trouble Analysis. .............................. 42
5-12.
Removal 47
5-15.
Minor Repair and Replacement.. ... .. . .. . .. ..... 47
5-23. Alignment and Adjustment _ '. ..... 49
5-27. Lubrication 49
5-29.
Inspection Schedule 49
VI FIELD AND FASRON MAINTENANCE...................... 52
6-1. Minimum Performance Standards.. . . . . . ... . . . .. ........ 52
6-3. Systems (Trouble) Analysis. ............................ 52
6-8. Removal. ............................................ 57
6-15.
Circuit Breakdovvn .59
6-16.
Tube Socket Voltage and Resistance Charts. . . . . .. . . . . . . . 60
6-18. Supply Voltage Diagram. . .... ........... ... ........... 63
6-21.
Alignment and Adjustments. ........................... 63
6-23.
Lubrication 64
6-24.
Maintenance and Inspection Schedule . --- -. - . . . . . . . . . . . . 65
6-38.
Overhaul Schedule 69
VII DIAGRAMS. ............................................... 70
INDEX................................ 76

Section IAN
16-45-434
(
ii
Figure 1-1. Radio Receiver, Diversity Model SP-600-JX-17 Rack Mountings

AN 16-45-434
SECTION I
DESCRIPTION AND LEADING PARTICULARS
Section I
Paragraphs 1-1 to 1-7
1-1. GENERAL.
1-2. The service instructions outlined herein pertain
to the Radio Receiver, Diversity Model SP-600-JX-17
rack mountings (figure 1-1), manufactured by the
Hammarlund Mfg. Co. Inc., New York 1, N. Y. The
radio receiver, designed for mounting in a standard
19-inch relay rack, consists of achassis and light grey
front panel assembly to which are mounted a top cover
and a bottom plate. It is a20-tube radio communi-
cations receiver with six frequency bands for the con-
tinuously variable, selective reception of any signal
within the frequency range of 0.54 to 54.0 mc. It has
added provision for the fixed-frequency crystal-con-
trolled reception of any signal within the frequency
range of two to 30.0 mc.
1-3. The receiver is of the superheterodyne type. On
the three lower frequency bands (0.54 to 7.4 mc) the
signal tuned in is heterodyne converted to 455 kc. On
the three higher frequency bands (7.4 to 54.0 mc) the
signal tuned in is double heterodyne converted to
455 kc, the initial conversion frequency used being
3,955 kc.
1-4. The receiver self-contained stabilized power sup-
ply is designed to operate from a single phase 50- to
60-cycle, a-c source. The po.wer transformer primary
is provided with taps covering a line voltage range
from 90 to 270 volts. The receiver is protected against
overload by fusing the power transformer primary and
secondary plate windings. The primary and secondary
fuses used are contained respectively in the "1.6A
SLO" and "3/8A" "FUSE" holders (1 and 2, figure
1-3) on the rear apron of the receiver. A duplicate
of each of these fuses, comprising the receiver spare
fuse complement is located under the polystyrene
"SPARE FUSES" cover (3), retained by th'e captive
screw (4). The receiver "AC POWER" connector (5)
provides for plug connecting the a-c line source to
the receiver.
To prevent damage, maintain the fuse
complement.
1-5. PURPOSE AND LIMITATIONS.
1-6. The receiver is designed for use in fixed and/or
mobile operations such as are 'encountered at enclosed
base stations, aboard ship, or when airborne, even
when such activities are subjected to wide ranges in
temperature and humidity. The receiver is adequately
treated with fungicidal varnish to condition it for
tropical use. Its design and shielding reduce its radia-
tion characteristics to apossible minimum, thereby
complying with shipboard regulations and enabling
the receiver to be operated in close proximity to all
other station e,quipment such as is encountered in
multi-receiver installations. It is suited to two-way
operational activities and may be "desensitized" in the
presence of a strong local carrier, through use of the
"SEND" "REG' switch (1, figure 1-2) in its "SEND"
position. The receiver is suited espe<;ially for use in
frequency-shift spacediversity receiving systems. When
properly interconnected, two receivers may, be operated
so that one receiver is heterodyne slave connected to
the other, or an externally connected master oscillator
unit may be used to provide the heterodynes for both
receivers. To provide for a common 3.5. mc crystal-
controlled heterodyne between receivers, the "IFO'!
connector (6, figure 1-3) of each receiver is inter-
connected and the "IFO" "EXT" "INT" switch (2,
figure 1-2) of the slave receiver is set to "EXT". Like-
wise, for the fixed-frequency crystal-controlled hetero-
dyne, the "HFO OUTPUT" connector (figure 5-4) of
each is interconnected, and the "HFO" "V AR" "EXT"
"XTALS" "I" "2" "3" "4" "5" "6" switch (3, figure
1-2) of the slave receiver is set to "EXT". Likewise,
for the bfo heterodyne, the "BFO" connector (7, figure
1-3) of each is interconnected, and the "BFO-AVC"
"EXT BFO" "SLOW" "FAST" "INT BFO" "SLOW"
"FAST" switch (4, figure 1-2) of the slave receiver is
set to one of its "EXT BFO" positions.
1-7. The receiver is designed to provide for the recep-
tion of amplitude-modulated, suppressed carrier, keyed-
carrier, and frequency-shift signals. For the reception
of radio telephone or low-speed (manual) telegraph
a headset is plugged in the "PHONES" jack (5, figure
1-2) contained in the front panel, or a loud speaker
is connected to the "AUDIO OUTPUT" terminals
(8, figure 1-3) on the rear apron. For the reception of
high-speed (automatic) telegraph, the receiver doc out-
put developed between the jumpered "DIODE OUT-
PUT" terminals (9, figure 1-3) and chassis ground,
may be used to operate a tape ink recorder, or the
receiver a-c output developed at the "AUDIO OUT-
1

Section I
Paragraphs 1-8 to 1-9
AN 16-45-434
PUT" terminals (8, figure 1-3) may be used to operate
a recorder driving unit associated with the tape ink
recorder. For the reception of frequency-shift teletype,
the receiver 455-kc i-f output developed at the "IF
OUTPUT" connector (10, figure 1-3) or the receiver
a-f output developed at the "AUDIO OUTPUT" ter-
minals (8, figure 1-3) may be used to operate suitable
frequency-shift receiver converter equipment associated
with a teletypewriter. For the reception of keyed-
carrier, single or two-tone carrier teletype, the receiver
a-f output developed at the "AUDIO OUTPUT" ter-
minals (8, figure 1-3) is used to operate suitable
demodulator equipment associated with a teletype-
writer.
1-8. LEADING PARTICULARS.
1-9. The receiver antenna system used is connected to
the "ANT" input connector (11, figure 1-3). The
receiver' input impedance is designed to match a
95-ohm coaxial cable for optimum coupling. A straight
wire antenna system, preferably of the Beverage (wave
antenna) fishbone type, is used with the receiver.
/
5 21
4
13
3
12
1. "SEND" "REC" switch
2. "IFO" "EXT" "INT" switch
3 .. "HFO" "VAR" "EXT" "XTALS"
"6" switch
4. "BFO-AVC" "EXT BFO" "SLOW" "FAST"
"INT BFO" "SLOW" "FAST" switch
5. "PHONES" jack
6. "BAND CHANGE" control
7. "MEGACYCLES" window
8. Main tuning dial
9. Vernier dial
10. "TUNING" control
11. "TUNING LOCK"
12. Plastic chart
13. "HFO" "/:,. FREQ" control
14. "RF GAIN" control
15. "AVC" "MAN" switch
16. "METER" "RF" "AF" switch
17. "MOD" "cw" switch
18. "BEAT OSC" control
19. "SELECTIVITY" switch
20. "XT AL PHASING" control
21. "LIMITER" "OFF" switch
22. "AUDIO GAIN" control
2
figure J-2. Radio Receiver, front Panel View

AN 16-45-434 Section I
2
I
P5
P8
II
15
17
y .......
P6
P7
P2
16
12
14
"lP--!'---13
P4
1. "1.6A SLO FUSE" holder
2. "3/sA FUSE holder
3. "SPARE FUSES" cover
4. Captive screw
5. "AC POWER" connector
6. "IFO" connector
7. "BFO" connector
8. "AUDIO OUTPUT" terminals
17.
9. "DIODE OUTPUT" "A VC" terminals
10. "IF OUTPUT" connector
11. "ANT" inp~t connector
12. "REMOTE" connector
13. "METER AD] RF" control
14. "METER AD] AF" control
15. Allen wrench, No.6
16. Allen wrench, No.8
Allen wrench, No. 10
figure J-3. Radio Receiver, Rear View of Chassis
3

Section I
Paragraphs 1-10 to 1-16
AN 16-45-434
1-10. The receiver rotary turret houses the frequency
determining r-f tuner subassemblies for each of the
six frequency bands of the receiver. Each frequency
band has an antenna, two identical interstage, and an
oscillator r-f tuner subassembly. Through use of the
"BAND CHANGE" control (6, figure 1-2) the rotary
turret is indented to select the frequency band desired.
The "BAND CHANGE" control (6) knob is turned
360 degrees to indent an adjacent band. It may be
turned and indented in either direction. The band
indicator dial visible through the "MEGACYCLES"
window (7) indicates the frequency band selected.
The "BAND CHANGE" control (6) also locates the
dial frequency indicator of the main tuning dial (8)
to the proper frequency scale <?n the dial. The main
dial arbitrary outer scale, in' conjunction with the
vernier dial (9) scale provide a continuous vernier
scale for each frequency band for extremely accurate
station logging and receiver resetability.
1-11.
The single "TUNING" control (10, figure 1-2)
is large and flywheel balanced to provide operating
ease at high traverse speeds. It controls both the main
and vernier dials. An anti-backlash gear train main-
tains the extremely close calibration accuracy and
provides for the accurate resetability of the receiver.
The "TUNING LOCK" (11) provides locking action
without affecting the frequency setting. The tuning
ratio from the tuning control to the main dial is 50
to one and the ratio from the vernier dial to the
main dial is six to one.
1-12. The receiver circuitry available for single con-
version includes two stages of r-f amplification, a
mixer, a heterodyne oscillator, four stages of i-f
amplification, a detector and an a-v-c- rectifier, anoise
limiter and a meter rectifier, a beat-frequency oscilla-
tor, a beat-frequency buffer amplifier, an i-f output
stage, an a-f amplifier, and an a-f output power stage.
The receiver circuitry available for double conversion
does not include the initial gate stage of the i-f ampli-
fier, used for single conversion, but includes asecond
mixer and asecond heterodyne crystal-controlled
oscillator.
The receiver self-contained power ~upply
system includes afull-wave power rectifier and voltage
regulator, and afull-wave bias rectifier.
1-13. For fixed-frequency crystal-controlled reception,
the variable frequency first heterodyne oscillator is
replaced by afixed-frequency crystal-controlled oscilla-
tor. This is done when the "HFO" "V AR" "EXT"
"XTALS" "I" "2" "3" "4" "5" "6" switch (3, figure
1-2) is switched from its "V~O" to one of its "XTALS"
"I" "2" "3" "4" "5" or "6" switch positions. The
switch position chosen is that which is associated with
and is fitted with acrystal suited to the frequency
of the operational activity contemplated. The small
plastic chart (12) is used to pencil in or ink-record,
at the numbered line provided for each crystal holder,
the applicable signal frequency of the crystal fitted in
the holder. To provide for reception, the main dial is
set
to the signal frequency and tuning is accomplished
4
through use of the "HFO" "/I.. FREQ" control (13).
A
slight tuning adjustment in the chosen setting of
the "TUNING" control (10) is desirable, to resonate
the r-f section to the signal.
1-14. The frequency control unit crystals, as per Mili-
tary Specification MIL-C-3098, provided the opera-
tional activity should be purchased on special order
to Hammarlund Specification No. 31473. The operat-
ing frequency of each crystal for single conversion use,
to and including 7.4 mc, is specified as the signal
frequency plus 455 kc; and for double conversion use,
from 7.4 mc to 12.0450 mc, it is specified as the signal
frequency plus 3,955 kc. For signal frequencies from
12.0450 to 30.0000 mc the third harmonic mode of
operation of the crystal is used such that the crystal
frequency specified is the signal frequency plus 3.955
mc divided by three. The allowable frequency toler-
ance of each crystal is 0.005 percent of frequency.
1-15.
The receiver front panel dual scale meter pro-
vides an r-f indication of the relative strength of the
received signal in decibels from one microvolt with
the "RF GAIN" control (15, figure 1-2) fully on,
when the "A VC" "MAN" switch (15) is in its "A VC"
position. The r-f indication is used for tuning when on
avc. When the "METER" "RF" "AF" spring return
switch (16) is held depressed in its "AF" position, the'
lower scale of the meter indicates the receiver audio
output power level in decibels from six milliwatts
standard reference output. .
1-16.
The receiver provides for the avc of the signal
tuned in when the "A VC" "MAN" switch (15, figure
I~2) is in its "AVC" position. The receiver signal gain
maintained is dependent on the setting chosen for the
"RF GAIN" control (14). The receiver avc time con-
stant is "fast" or "slow" dependent on whether the
"BFO-A VC" "EXT BFO" "SLOW" "FAST" "INT
BFO" "SLOW" "FAST" switch (4) is set to either of
its two "FAST" or either of its two "SLOW" switch po-
sitions. With the "MOD" "CW" switch (17) in its "cw"
position and the switch (4) in either of its "INT BFO"
"SLOW" or "FAST" positions, the receiver internal
bfo is utilized by the receiver. Again, when the switch
(4) is in either of its "EXT BFO" "SLOW" or "FAST"
positions, the bfo connected to the "BFO" connector
(7, figure 1-3) is utilized by the receiver. With the
"MOD" HCW" switch (17) in its "MOD" position,
the receiver internal bfo may be switched on through
the closing of a switch remotely connected to the
"REMOTE" connector (12, figure 1-3), Band C pin
terminals. The A and D pin terminals of the connector
(12) provide for the tone modulation of a received
cow signal through use of an externally connected
tone generator associated with the receiver. This is
done when the receiver mode of operation used for
the cow reception is mcw, as is the case when the
"MOD" "cw" switch (17) is in its "MOD" position,
so that the receiver audio output developed is at a
steady
tone pitch with the accompanying advantages.
For normal keyed carrier reception, the receiver

T.O. 31R2-4-18-2
TABLE 1-1. TUBE COMPLEMENT
Section I
Paragraphs 1-17 to 1-22
I
I
JAN TYPE
QUANT
FUNCTION REFERENCE SYMBOL
6BA6 or
7Amplifiers; r-f, i-f, b-f-o buffer.
VI, V2, V7, V9, V10, VII,
5749/6BA6W
V12
6C4 3Oscillators;
var freq., 3.5 mc, bfo. V4, V8, V13
6AH6 1Oscillator;
freq control. V3
6BE6 2Mixers; 1st,
2nd. V5,V6
6AL5 or 5726/
3
Detector and avc; limiter and meter; bias recto V14A, B; V15A, B; V20
6AL5W/6097
12AU7 1
Cathode follower and 1st audio. V16
6V6GT 1Audio
power output.
.V17
5R4GY 1Rectifier.
V19
OA2
1
Voltage regulator.
V18
"BEAT OSC" control (18) may be set to provide
receiver single-tone output at any pitch within the
range of plus or minus three kc from zero tone output.
For frequency-shift reception, the two-tone receiver
output provided is dependent on the setting chosen for
the control (18) and on the carrier frequency-shift.
1-17. The receiver provides effective a-v-c action so
long as the rate of signal fading does not approach
the signal speeds used. Whenever the signal carrier is
present at all times such as for m-c-w or frequency-
shift reception, the "fast" receiver a-v-c time constant
is used, since its use tends to overcome more rapid
rates of selective and non-selective fading. When the
signal is a
cow (keyed carrier) signal, use of the "slow"
receiver a-v-c time constant is necessary to provide for
the a-v-c bus, smoothing action with regard to the
low frequencies comprising high-speed (automatic)
cow signals. The "slow" and "fast" receiver a~v-c time
constants are
both effective in the presence of slow
fading.
To effectively overcome rapid rates of fading,
the space diversity receiving system used, usually
utilizes
two or three receivers, dependent on whether
afrequency-shift or keyed-carrier, respectively, are to
be received. The "A VC" terminals (9, figure 1-3) when
interconnected between receivers in aspace diversity
receiving system, enable
the more negative bias, de-
veloped by the signal on one receiver, to further reduce
the weaker signal and noise due to the other receiver.
1-18. The receiver "SELECTIVITY" switch (19, figure
1-2) provides achoice as to anyone of six degrees of
receiver selectivity, the three narrower "SHARP" band-
widths being realized through use of the crystal filter
forming part of the i-f section of the receiver. The
crystal filter "XTAL PHASING" control (20) with the
switch (19) in anyone of its "SHARP" positions,
provides
for highly attenuating heterodyne interfer-
ence even when the unwanted signal is closely adjacent
to the desired signal tuned in. In the instance of noise
of the pulse type, such as that due to ignition systems,
Revised 10 September 1955
the receiver noise limiter, with the "LIMITER" "OFF"
switch (21) in its "LIMITER" position, provides for
the receiver noise to be bypassed from the receiver
audio
output.
1-19. PERTINENT DATA.
1-20. TUBE COMPLEMENT. The 20 electron tube
complement of the receiver is shown in table 1-1.
The table identifies each tube by JAN type designa-
tion, circuit reference symbol
and circuit function.
1-21. FUSE COMPLEMENT. The fuse complement
of the receiver (table 1-2) comprises two fuses and
aspare for each. Each fuse is glass-enclosed, indicating,
and commercially available. The three-eighths ampere
fuse is
of the instantaneous type and the 1.6 ampere
fuse is
of the slow-blow time delay type. The table
identifies each fuse by Bussman
Mfg. Co. part number,
ampere
rating, circuit reference symbol, and type.
TABLE 1-2. FUSE COMPLEMENT
BUSSMAN QUANT-
AMPERE REFERENCE
PART NO.
ITY
RATING
TYPE
SYMBOL
AGC3/8
2
3/8
Cartridge
F2
MDL 1-6/10 2
1-6/10
Cartridge F1
A125V
FUSETRON
1-22. FREQUENCY RANGE AND STABILITY. The
six frequency bands of the receiver provide for con-
tinuous reception
within the frequency range of 0.54
. to 54.0 mc. Subsequent to a15-minute warm-up period,
the receiver frequency drift, as apercentage of the
signal frequency tuned in, ranges from 0.001 to 0.01
percent.
This frequency stability approaches that pro:
vided by the receiver for fixed-frequency crystal-con-
trolled reception, within the frequency range of two to
30.0 mc. s

Section I
T.O. 31R2-4-18-2
NUMBERS DENOTE SELECTIVITY SWITCH POSITIONS
i,2AND3 NON CRYSTAL - 4,5AND6 CRYSTAL
1
15
2
10
36 54
45 6
505
KC OFF RESONANCE
3
10
2
i5
1\
\ \ I•
\,\,,J
1\ \I I I
~ ~
1I
II
\
.~
'I
~
1\
JJ
1\
,,
II
~
\ 1\
~
JI
,\I
~
~
IJ
'\
J
1
1\
1\ 1\
J
1\ \I
\,J
II
~
II
II
1\ 1\
~
J
,,J
~
I
1\
,
~
~
\,\
II
1f
\JI
,II
~
\JJJ
~, \V/
~
r-.,-~
~ ~~~
~""""
1
10
100
1000
1
I-
:::>
Q..
Z
w
u
z
<{
z
o
c.n
W
0:::
c.n
W
~
I-
Figure 1-4. Overall Selectivity Curves at Two Megacycles
6

AN 16-45-434
Section I
Paragraphs 1-23 to 1-28
1-23. TUNING BAND RANGES. The tunable fre-
quency range of each of the six frequency bands of
the receiver is shown in the table 1-3. The innermost
scale of the main tuning dial is that for the lowest
frequency range. The band numeral assigned each band
is an arbitrary designation.
TABLE 1-3. TUNING BAND RANGES
BAND NO.
FREQUENCY RANGE
10.54 to
1.35 mc
21.35 to
3.45
mc
33.45
to
7.40
mc
47.40 to-14.80 mc
514.80
to 29.70 mc
629.70
to 54.00 mc
1-24. OUTPUT CHARACTERISTICS. The maximum
undistorted power output of the receiver is two watts.
The receiver audio output terminals, phones jack, and
i-f output connector are respectively designed for
600-ohm, 8,000-ohm, and 70-ohm resistive matching
loads. For an arbitrary level of 500 milliwatts of audio
output to a 600-ohm load there obtains 15 milliwatts
of phones output; and with two microvolts receiver
signal input the i-f output to a 70-ohm load is a
minimum of six-tenths of a milliwatt. The h-f-o, i-f-o,
and b-f-o 70-ohm connector matching outputs are con-
sidered normal when the slave-connected receiver de-
velops its mini):Ilum performance standards as speci-
fied
in tables 5-1 and 6-1.
1-25. SENSITIVITY. The m-c-w sensitivity of the re-
ceiver to any signal frequency within its tuning range
is two microvolts or better, for a signal-plus-noise to
5
noise power ratio of 10 to one at the receiver audio
output terminals. Similarly, the cow sensitivity of the
receiver is 0.75 microvolts, or better.
1-26. SELECTIVITY. The receiver selectivity or band
pass characteristics provided for each of the six posi-
tions of the selectivity switch are shown in figure 1-4.
The semi-log graph plot shown for each curve shows
the kc off resonance, above and below the nominal
two megacycles signal frequency, for multiples of the
resonant input, at which the receiver audio output
level is equal to that chosen at resonance.
1-27. FIDELITY. The graph plots (figure 1-5) show
the overall and the audio output attenuation in deci-
bels, versus frequency characteristics of the receiver.
SOLID CURVE is the fidelity of the audio
frequency amplifier with input applied be-
tween terminal 3 of R84 (figure 7-2), and
ground, and with the r-f gain control at min.
DOTTED CURVE is the overall fidelity at
2.5 mc; AM of 30 percent, selectivity switch
in 13 kc position, and r-f gain control set for
10 mw reference level output.
In each instance, the output is measured across
a 600-ohm resistive load and audio gain con-
trol set at max.
1,;-:.28. REJECTION RATIOS. The image rejection
ratios of the receiver, at the high frequency end of
each receiver band, expressed as a voltage ratio and
in decibels, is shown in table 1-4. The 455-kc i-f
rejection ratio of the receiver is 69 db with the receiver
tuning mechanism set to tune in a600-kc signal. This
ratio, applicable to single conversion, improves with
frequency for bands 1, 2, and 3. The 3,955-kc i-f rejec-
tion ratio of the receiver, applicable to double con-
version, is a minimum of 94 db with the receiver
tuning mechanism set to tune in any signal within the
frequency range of bands 4, 5, and 6.
ai
o
z
z
o
fi
. :::>
z
w
~
~
~
:::>
Q..
~
:::>
o
o
5
10
15
20
-
....
1"'1I
.-- -
---
"'"
- ..
l..ol'.
-'
.~ .
"
.,
i
,
~.
-
I.
100 1000
CYCLES PER SECOND
Figure 1-5. Audio and Overall Fidelity Curves
10,000
7

---------------------------------------- -~-
Section IAN 16-45-434
Paragraphs 1-29 to 1-43
1-32. OPERATING AND ADJUSTMENT
CONTROLS.
1-29. AUTOMATIC VOLUME CONTROL. The a-v-c
action maintains the receiver output constant within
14 db when the input is increased from two to 200,000
microvolts.
1-31.
TEMPERATURE AND HUMIDITY. The per-
missable ambient temperature of the receiver may
range from 0° C(32°F) to 60°C (140°F), at a relative
humidity as high as 95 percent.
1-35. "MOD" "CW". The "MOD" "cw" switch (17,
figure
1-2) in its "cw" position switches "on" the
bfo of the receiver. The "MOD" position of the switch
is used for m-c-w reception and the "cw" position
of the switch is used for suppressed carrier and keyed-
carrier reception; also for frequency-shift reception
when the receiver audio output is required for the
frequency-shift converter, or when the audio output is
to provide monitoring signal to the receiver headset
used.
TABLE 1-4. IMAGE REJECTION RATIOS 1-36. "BAND CHANGE". The "BAND CHANGE"
control (6, figure 1-2) provides for choosing and in-
denting the frequency band of the receiver within the
frequency range of which is the signal frequency to
be tuned in.
1-37. "TUNING". The "TUNING" control (10, fig-
ure 1-2) is used to tune in the signal to resonance.
1-38. "TUNING LOCK". The "TUNING LOCK"
(11, figure 1-2) is used to lock the tuning mechanism
at the tuning setting chosen.
1-39.
"IFO" "EXT" "INT". The "IFO" "EXT" "INT"
switch (2, figure 1-2) provides achoice as to the "INT"
(internal) 35-mc double conversion crystal-controlled
heterodyne oscillator of the receiver or that externally
connected to the "IFO" connector (6, figure 1-3). When
the switch is set to its "EXT" (external) position, the
receiver oscillator is inoperative.
1-40. "BFO-AVC" "EXT BFa" "SLOW" "FAST"
"INT BFa" "SLOW" "FAST". The "BFO-AVC"
"EXT BFa" "SLOW" "FAST" "INT BFa" "SLOW"
"FAST" switch (4, figure 1-2), is associated separately
both with the b-fo and a-v-c circuitry of the receiver.
When it is set to either of its "INT BFa" "SLOW"
or "FAST" positions, it provides for the use of the
internal bfo of the receiver. When it is set to either
of its "EXT BFa", "SLOW" or "FAST" positions, it
provides for the receiver use of the external bfo con-
nected to the "BFa" connector (7, figure 1-3). The
separate switch arrangement is such that whether the
switch is switched for use of the internal or externally
connected bfo, the a-v-c time constant provided the
receiver may be chosen as "SLOW" or "FAST". Either
"SLOW" position of the switch provides for increas-
ing the avc time constant substantially over that pro-
vided for either "FAST" position. In choosing the
switch position desired, first determine whether the
internal or an external bfo is to be used and then
choose a slow or fast a-v-c time constant, as outlined
in paragraph 1-17.
1-41. "SELECTIVITY". The "SELECTIVITY" switch
(19, figure 1-2) provides choice as to three knob dial
"XTAL" (crystal) and three "NON-XTAL" (non-
crystal) positions of receiver selectivity. The six posi-
tions provide selectivity steps ranging from a "SHARP"
to a "BROAD" knob dial indication. The "XT AL"
switch positions provide six decibel bandwidths of
0.2, 05, and 1.3 kc, and the "NON-XTAL" switch
positions provide six decibal bandwidths of 3.0, 8.0,
and 13.0 kc.
1-42. "XTAL PHASING". The "XTAL PHASING"
control (20, figure 1-2) is used to highly attenuate
heterodyne interference closely adjacent to the desired
signal. It provides this function only when the "SE-
LECTIVITY" switch (19) is in one of its three "XT AL"
knob dial positions.
1--43. "BEAT OSC", The "BEAT OSC" control (18,
figure 1-2) is used to provide receiver single-tone out-
put and two-tone output, respectively, for the reception
IMAGE REJECTION RATIO
BAND NO. FREQUENCY VOLTAGE RATIO DB
11.35 mc
60,000
95
23.40 mc 10,000 80
37.40
mc
4,000 72
4
1450 mc
300,000 109
529.50
mc
50,000 94
654.00
mc 5,000 74
1-30. LINE SUPPLY REQUIREMENTS. An a-c,
single-phase, 50-
to 60-cycle power source within the
voltage range of 90 to 270 volts is required to provide
input power to the receiver. The receiver power trans-
former 95, 105, 117, 130, 190,210,234, or 260 primary
voltage tap used is that whose voltage rating most
closely agrees with that of the available a-c source.
For an a-c line voltage of 117 volts, the receiver current
drain is 1.25 amperes and its power consumption is
130 watts.
The maximum starting current is two am-
peres.
1-33. The receiver operating and adjustment controls,
respectively, are located on the front panel (figure 1-2)
and on the rear apron (figure 1-3). The controls are
referred to below by their front panel and rear apron
designations.
1-34. "SEND" "REG'. The "SEND" "REG' switch
(1, figure 1-2) is used to switch the receiver from its
"REG' (receive) condition to a "desensitized" "SEND"
condition in the presence of a strong local carrier.
When switched back to "REG' the receiver is ready
for instant use.
8

AN 16-45-434
Section I
Paragraphs 1-44 to 1-52
of a keyed-carrier or a frequency-shift signal, when
operating cwo The pitch of the tone or tones, as ap-
plicable, is dependent on the chosen setting of the
control. The control may be set on scale in either direc-
tion from its "0" knob dial position. It provides for a
plus and minus three-kc tone range. To provide for
suppressed carrier m-c-w reception, the control, when
set to its "0" knob dial position, provides for the
b-f-o output as the 455-kc reinserted carrier.
1-44. "RF GAIN". The "RF GAIN" control (14, figure
1-2) is used to switch the receiver "on" when turned
clockwise from its "OFF" knob dial position to a point
where a "click" is heard. The further clockwise turning
of the control increases the r-f and i-f gain of the
receiver. To prevent overloading the receiver r-f and
i-f sections, when not on ave, the control is turned
down somewhat from its maximum gain position,
normally used when on ave. The control is turned
down when on ave to reduce the sensitivity of the
receiver during "off" and fading periods of the signal,
so that the otherwise undesirable receiver noise output
may be reduced. When two or more receivers are used
in aspace diversity receiving system, the "RF GAIN"
control (14) of each receiver, apart from that with the
lesser signal level, is set so that the signal level of
each receiver is the same.
1-45."
"AVe" "MAN". The "AVC" "MAN" switch
~ (15, figure 1-2) is used to switch from ave to manual
:ontrol of the receiver r-f and i-f gain, determined by
the setting of the "RF GAIN" control (14). The "RF
GAIN" control (14) is operative in either the "MAN"
(manual) or "A VC" (ave) position of the "A VC"
"MAN" switch.
1-46. "METER" "RF" "AF". The "METER" "RF"
"AF" spring return switch (16, figure 1-2) is associated
with the dual scale meter. In its normal "RF" position,
with the "RF GAIN" control (14) full on, the switch
provides for a calibrated r-f meter i,?di~~tion .. ~he~
the switch is held in its depressed AF posHl0n It
provides for a calibrated a-f meter indication.
~
To avoid meter damage, set "AUDIO GAIN"
control (22, figure 1-2) fully counter-clock-
wise,
then depress meter switch, and t~en
slowly increase audio level to the deSIred
meter scale indication.
1-47. "AUDIO "GAIN". The "AUDIO GAIN" control
(22, figure 1-2) is used to adjust the rece.iver ~~dio
)utput to alevel providing for comfortable mtelhglble
reception. The receiver- -audio -output is adequate to
operate any recording equipment used, but make sure
that the control position chosen provides for un-
distorted receiver output as specified in paragraph 1-24.
1-48. "LIMITER" "OFF". The "LIMITER" "OFF"
switch (21, figure 1-2) in the "LIMITER" position
provides for pulse-type noise, such as that due to igni-
tion systems, to be bypassed from the receiver audio
output. Unless such noise is interfering with the
reception, keep the switch in its "OFF" position.
1-49. "HFO" "VAR" "EXT" "XTALS" "1" "2" "3"
"4" "5"
"6". The "HFO" "VAR" "EXT" "XTALS"
"1" "2" "3" "4" "5" "6" switch (3, figure 1-2), when
set to "V AR", switches the receiver for variable fre-
quency reception. When the switch is set. to one of
its (XTALS" (1", tt2", H3", «4", «(5", or H6" switch
positions, the receiver provides for fixed-frequency
crystal-controlled reception at the signal frequency of
the crystal contained in the holder associated with the
switch position chosen. When the switch is set to
"EXT" the fixed-frequency crystal-controlled first
heterodyne oscillator, conpected to the receiver "H~O
OUTPUT" connector (see figure 5-4), replaces that, m-
ternal to the receiver, associated with each crystal
switch position.
1-50. "HFO" "1',.. FREQ". The "HFO" "1',.. FREQ"
control (13, figure 1-2) is used to accurately tune in
the signal when the internal fixed-frequency crystal-
controlled first heterodyne oscillator provides for fixed-
frequency crystal-controlled reception. The control pro-
vides for a slight adjustment in the frequency of the
oscillator, necessitated by the 0.005 percent frequency
tolerance inherent to each crystal used; also refer to
paragraph 1-14. The "HIGH" "3" "2" "I" "0" "1" "2"
"3" "LOW" panel marking designates an arbitrary
frequency scale for the control setting, a more clock-
wise
setting indicating a relatively lower oscillator
frequency.
1-51.
"METER AD] RF". The "METER AD] RF"
control (13, figure 1-3) is used to calibrate the r-f
scale of the dual scale meter. With a 10-microvolt input
signal and the "RF GAIN" control (14, figure 1-2)
fully on, the "METER AD] RF" control is set for an ref
meter scale reading of +20 db.
1-52.
"METER AD] AF". The "METER AD] AF"
control (14, figure 1-3) is used to calibrate the a-f
scale
of the dual scale meter. With a600-ohm resistive
load connected to the "AUDIO OUTPUT" terminals
(8) and 1.9 volts or six milliwatts of audio output,
the "METER AD] AF" control is set to provide a zero
db a-f meter scale reading.
9

Section /I
Paragraphs 2-1 to 2-7
AN 16-45-434
SECTION II
TEST EQUIPMENT AND SPECIAL TOOLS
2-1. TEST EQUIPMENT.
2-2. No special test equipment is required to align,
final-test, or service the radio receiver.
2-3. SPECIAL TOOLS.
2-4. The special tools procured for the maintenance of
the radio receiver are listed in table 2-1. The receiver
is provided with two Fahnstock type clips to hold the
three Allen wrenches.
2-5. CABLE FABRICATION.
2-6. ANTENNA CABLE. The antenna fabricated cable
(see figure 2-2) is used to provide signal generator
access. to· the antenna input connector of the receiver.
It comprises the parts, identified by Hammarlund part
number, shown in figure 2-2.
2-7.
CATHODE FOLLOWER CABLE. The cathode
follower fabricated cable is used (see figure 2-3) to
load the i-f output connector and provides for con-
necting an output meter. It comprises the parts, iden-
tified by Hammarlund part number, shown in figure
2-3.
TABLE 2-1. SPECIAL TOOLS REQUIRED FOR MAINTENANCE
FIGURE AND HAMMARLUND
INDEX NO.
PART NO. NAME APPLICATION
1-3, 15
11806-2 Wrench, Allen
Set Screw, No.6
1-3, 16
11806-3 Wrench, Allen
Set Screw, No.8
1-3,17
11806-4 Wrench, Allen
Set Screw, No. 10
2-1
T8222
Pliers, Special Spring, flat; for r-f tuners.
Figure 2-1. Special Pliers
TO SIGNAL
GENERA~
NO.19309-25BF
100 OHMS
SOLDER-
~-- NO. 15930- 59
(APPROX 30 IN. LONG)
NO. 16071-1
(PL-259)
/
/
!
~ TO ANTENNA INPUT CONNECTOR
Figure 2-2. Antenna Cable
10

AN 16-45-434
Sections II-III
NO.I607H
L... OUTPUT
CONNECTOR
NO. 19309-2\ SF
68 OHMS
Figure 2-3. Cathode Follower Cable
SECTION III
PREPARATION FOR
USE AND RESHIPMENT
3-1. PREPARATION FOR USE.
3-2. UNCASING. The radio recevier is packed at the
factory, for shipment. The outer wooden case encloses
a
carton which contains the receiver proper and a bag
containing the receiver cable plug connectors. The ca-
ble plug connectors are removed from the receiver for
shipment purposes.
a. Cut and fold back the steel straps, adjacent to the
wooden case cover.
b. Remove the cover nailed to the case.
c.
Remove carton containing receiver and plug con-
nectors from case.
d. Remove waterproof tape from folds in waterproof
covering wrapped around carton, and then remove
the waterproof paper wrapper; then open the carton.
e. Remove wood frame from carton; also corrugated
interiors comprising two side pieces, one front, one
back, and one top, each accordion folded; also, the
bag containing the receiver plug connectors.
f. Remove the receiver and place it out of the way
in a convenient place near its final location.
g. Remove the receiver plug connectors from the
outer cloth and inner paper bag containing them;
also from plastic bags, as applicable.
m. Put all packing material in the wooden case
and store.
3-3. SETTING UP RECEIVER.
3-4. PRIMARY TAP USED. When shipped, the radio
receiver power trnasformer primary tap is connected
to operate from a50- to 60-cycle, lIS-volt a-c source.
The tap used is designed for a117 -volt a-c rating in
accordance with standard practice. Table 3-1 shows the
a-c source voltage rating of each primary tap, each of
which is identified by the numerical designation as-
signed it on the bottom of the power transformer.
Choose the power transformer primary tap
whose voltage rating is closest in agreement
with the a-c source voltage.
3-5. PLUG CONNECTOR ASSEMBLIES. Each plug
connector assembly (see figure 1-3), removed from the
receiver for purposes of shipment is listed in table
3-2. When unpacked, plug connect each to the receiver.
Each plug connector assembly is identified in table
3-2 by plug connector reference symbol, Government
Type designation of each assembly component, and lo-
cation.
TABLE 3-1.
POWER TRANSFORMER TAP VOLTAGE RATINGS
T\PNO. VOLTAGE RATING
295
3105
4117
5130
6190
7210
8234
9260
11

Section III
Paragraphs 3-6 to 3-10
AN 16-45-434
TABLE 3-2. PLUG CONNECTOR ASSEMBLIES
REMOVED FROM
RECEIVER FOR SHIPMENT
REFERENCE GOVERNMENT TYPE
SYMBOL DESIGNATIONS
CONNECTS TO
P2 PL-259;
with reducing 10, figure 1-3
adapter UG-176/U and
angle plug adapter M-359
P4 AN 3108B-14S-2P; with
12, figure 1-3
cable clamp AN 3057-6
P5
AN 3108B-18-3S; with cable
5, figure 1-3
clamp AN 3057-10
P6
PL-259; with reducing 6, figure 1-3
adapter UG-176/U and
angle plug adapter M-359
P7 PL-259; with reducing
7, figure 1-3
adapter UG-176/U and
angle plug adapter M-359
3-6. RECEIVER COMPONENT CONNECTING CA-
BLES.
When two radio receivers provide for the space
diversity
reception of afrequency-shift signal, the
crystal-controlled first, 3.5-mc second, and b-f-o hetero-
dynes
of either receiver may be separately cable-inter-
connected
to the other receiver, to provide for amaster-
slave
heterodyne relationship between the receivers.
The fabricated cables required to do this are listed in
table 3-3 and described in paragraph 3-7.
TABLE 3-3. RECEIVER HETERODYNE CONNECTING
CABLES
DESIGNATION
APPLICATION
"HFO OUTPUT" con- Fixed freq, crystal-con-
nector,
J8 cable. trolled first hetero-
dyne osc output at
J8.
"IFO"
connector,
J6
3.5 - mc
crystal - con -
cable.
trolled second heter-
odyne osc output at
J6.
"BFO"
connector,
]7
Beat-frequencyosc out-
cable.
put at]7.
3-7. HETERODYNE CABLE FABRICATION. The
receiver heterodyne cables (see table 3-3), terminate at
each receiver in a type PL-259 connector plug fitted
with a type UG-176/U reducing adapter. These fit-
tings (see figure 1-3), for one end of each interconnect-
ing cable, are supplied with each receiver. The inter-
connecting coaxial cable used (WE-724) is not sup-
plied as part of the receiver proper. The length of
WE-724 cable required to fabricate each heterodyne
cable is dependent on the relative receiver locations.
12
When the receivers are mounted in the same rack,
cable
lengths approximating 30 inches will suffice, but
actual measurements should be made for each con-
necting cable in each specific instance. To fabricate a
heterodyne connecting cable, cut the WE-724 coaxial
cable
to the required length and then, using a sharp
knife, expose the bare conductor to the extent of three-
quarters of an inch. Then thread this end of the cable
through the larger diameter end of the UG-176/U
reducing adapter so that a quarter-inch of the coaxial
cable shield
may be exposed. Now locate the reducing
adapter on the cable so that the exposed cable shield
can
be fully bent back over the end of the reducing
adapter. Now expose the bare conductor for another
quarter-inch. Then thread the cable, carrying the reduc-
ing adapter, into the PL-259 plug connector and
tightly screw the reducing adapter and the PL-259
plug connector together. Unscrew the knurled sleeve
of PL-259 and let it ride on the cable. The four small
holes in the neck of PL-259 should show that the cable
shield is
tightly clamped between the neck of PL-259
and the reducing adapter. Soldering of the shield to
the neck of PL-259 is optional. Use a click meter to
assure that no shield strands engage the conductor and
to indicate that the shield contacts the neck of PL-259.
Then solder the bare conductor at the end of the pin
terminal of PL-259, making sure that the solder does
not add to the pin outer diameter. Then snip off any
excess conductor extending past the pin terminal end.
Now replace the knurled sleeve of PL-259, by screw-
ing it back in place. Do likewise, as outlined, to the
other end of the cable to complete the fabrication of
the heterodyne connecting cable.
3-8. STORAGE.
3-9. When the radio receiver is to be stored, subse-
quent to use, remove the frequency control unit
crystals referred to in paragraph 1-13 and the plug
connector assemblies listed in table 3-2. Fully mesh
the eight-section, four-gang variable air capacitor and
then pack the receiver as outlined below in paragraph
3-10.
3-10. PACKING.
a. Open the folded receiver carton and tape all edges
with three-inch gummed kraft paper tape.
b.
Accordion fold the ends of a corrugated card-
board bottom for the carton, to act as a spring-board
bottom for the receiver. Then place it in the carton
with the accordion folds downward.
c. Place the receiver in the carton and cover the
receiver panel with wrapping paper.
d. Put into carton, around receiver, accordion folded
corrugated interiors, comprising two side pieces, one
front, one back, and one top, with the accordion folds
inward; also, one wood frame to act as a carton spacer.
e.
Put the receiver plug connectors listed in table
3-2 into the inner paper and outer cloth bags and
place into carton at the side of the receiver. Use the

AN 16-45-434
Sections III-IV
three plastic bags first, one each for each of the silver
plated connectors; press to exclude air and then heat-
seal.
f.
Complete taping up carton using the three-inch
tape.
g. Wrap carton in waterproof paper and seal all
folds with thr(:e-inch waterproof tape.
h. Put waterproof wrapped carton contammg re-
ceiver and plug connectors into wooden case.
i.
Nail cover on wooden case.
j.
Put two steel straps around case.
k. Stencil all markings on end of case.
1. Put address label on side of case.
SECTION IV
THEORY OF OPERATION
4-1. GENERAL SYSTEM OPERATION.
4-2. The radio receiver is designed to provide for
reception at each station in two-way single- or multi-
receiver military operational activities. It is especially
suited to dual-receiver frequency-shift space diversity
receiving systems, since it provides for fixed-frequency
crystal reception within the frequency range of two to
30.0 me and has provision for the common use between
receivers of its fixed-frequency crystal-controlled, first
and second heterodynes. Further, it has provision for
the common use between receivers of its b-f-o hetero-
dyne; also, for the use of common ave. Also it is suited
to any space diversity receiving system utilizing three
or more receivers, especially so since a master hetero-
dyne external oscillator unit may be used to provide
the heterodynes for each receiver. Due to the inter-
connecting and jumper opening provisions provided
on each receiver, the composite system doc output avail-
able for use may be that from one receiver.
4-3. FREQUENCW-SHIFT SPACE DIVERSITY
SYSTEM. OPERATION.
a. BLOCK DIAGRAMS. Figures 4-1 and 4-2, each
show in block diagram form the inter-relationship
existent between two radio receivers and the other
station components used in representative frequency-
shift space diversity receiving systems. The system
shown in figure 4-1 utilizes each receiver i-f output
and that shown in figure 4-2 utilizes each receiver a-f
output.
b. ANTENNA SYSTEM. To provide the frequency-
shift space diversity signal to the two receivers, an
antenna system, preferably of the Beverage wave an-
tenna fishbone type, is coaxial cable connected to the
antenna input connector of each receiver. To provide
for the space diversity feature, the two antenna systems
are spaced apart a distance equivalent to at least five
times the wavelength of the nominal signal carrier
tuned in.
c. AUXILIARY COMPONENTS. The teletype sig-
nal received is rendered audible and suitable for
teletypewriter use through the use of auxiliary com-
ponents associated with the receiving system. Apart
from the headset and/or loud speaker monitor used,
the auxiliary components used are dependent on
whether the i-f or a-f output from each receiver is to
provide for the composite signal. When each receiver
i-f output is used, the "IF OUTPUT" connector (10,
figure 1-3) of each receiver is coaxial cable connected
to the separate input connector provided each on the
frequency-shift receiver converter, forming part of the
system. The frequency-shift receiver converter doc
pulse, signal output developed is suited to operate the
teletypewriter connected to it, to provide a teletype-
written copy of the signal. When each receiver a-f
output is used, the "AUDIO 0lJ.TPUT" terminals (8,
figure 1-3) of each receiver are transmission line con-
nected to the separate input terminals provided for
each receiver on the radioteletype terminal equipment,
forming part of the system. The radioteletype terminal
equipment differentially wound relay is provided with
the composite pulse doc "space" output to one of its
windings and with the composite pulse doc "mark"
output to its other winding, the "mark" and "space"
pulses, respectively, causing the relay contacts, in
series with the doc line, to key the doc current in the
doc line to the teletypewriter, to provide a teletype-
written copy of the signal, as before.
d. MASTER-SLAVE OPERATION. The two receiv-
ers may be operated in amaster-slave heterodyne rela-
tionship through use of the receiver component
connecting cables listed in table 3-3. Connect the
cables between the two receivers and set the receiver
controls as outlined in paragraph 1-6. When each
receiver i-f output is used (refer to step "c" of subpara-
graph 4-3), and the bfo of each is used only to pro-
vide for its own monitoring output, then the use of
common bfo heterodynes between receivers is optional.
13

LL----- ---:t
,---;;A;:N::-:T--=:L:-=E~A~D::-:-::-:-.:-I N=-=- ---t TRANSF ;;;;;; ....
WE-724 CABLE MATCH ~tl J
FISHBONE WAVE ANTENNA
Section IV
ANT LEAD-IN
WE-724 CABLE
AN 16-45-434
TRANSF .r 1---- -- - --1:
MATCH !--::1;'""'""':z;--------......,.,.,,----1
T_.I:. I .>-ANTENNA LINE
FI SHBONE
WAVE ANTENNA ~ SURGE IMPEDANCE
MATOI
~'GNAL
I-------+--~TO HEADSET MONITOR
r-----------,
I
I )H-F-Q OUTPUT I
SP-600-JX-17 J--------~~TO HEADSET MONITOR
---~~-Q-ANT (MASTER)
AVC ) _ I-F OUTPUT
(-) IFOcBFO) ~
)H-F-O
OUTPUT
'--------+---o ...... ANT AVC
C)(_) I-F OUTPUT
_---fSP-600-JX-17 Clo- _~:........::....:.....;.
~ (SLAVE) (FO BFO
FREQUENCY- SHIFT
RECEIVER CONVERTER
TONE KEYER
~TO HEADSET
MONITOR
cC
---
SPEAKER
0
TELETYPE-
WRITER
I
UNIT
I
Figure 4-J. Frequency-shift Space Diversity, I-f Output Receiving System
14
--~-----------'--------~~~------ --- -~ ~

T.O. 31R2-4-18-2
Section IV
This is the case too, when the composite frequency-
shift receiver converter output is to be monitored. To
do this the frequency-shift receiver convener doc pulse
output is used to key "on" and "off" a tone sender,
which then provides monitoring signal to the headset,
plug-connected to it. When each receiver a-f output
is used, as outlined in step "c" of subparagraph 4-3, the
use of common b-f-o heterodynes between receivers is
desirable. This is so since the b-f-o "BEAT OSC" con-
trol (18, figure 1-2) of the master receiver provides
for the frequency of the "mark" and "space" tones
from each receiver to be identical and also since the
"BEAT OSC" control (18) on the slave receiver need
not be set. Make sure that the carrier frequency-shift
is known so that it can be taken into account when
setting the lllaster receiver "BEAT OSC" control (18)
so that the receiver two-tone output is accepted by the
band-pass filters in the radioteletype terminal equip-
ment. In the usual frequency-shift transmission the
spacing carrier frequency is 850 cycles lower in fre-
quency than the marking carrier frequency. Also, the
receiver "BEAT OSC" control (18) is usually set so
that the receiver a-f tone output for markings is 2,125
cycles
and for spacing 2,975 cycles, since the radio-
teletype terminal equipment band-pass filters usually
are desigrted for these frequencies. In such an instance
ANT LEAD -IN TRANSF
~W~E':'-_---':7=":2=":4":';C::"'A-B:':"':""L-E----""----I MATCH
:::!:: :::!:: ::=
T_ II
FISHBONE WAVE ANTENNA
§;GNAL
<»- ANTENNA LINE
>SURGE IMPEDANCE
MATCH
ANT LEAD-IN
WE-724 CABLE
l-I---------l
TR ANSF I='T'~'T'~=======~ =P==l
MATCH ~ ~ ::
L.I T
FISHBONE WAVE ANTENNA
)H-F-O OUTPUT I------_TO HEADSET MONITOR
SP-6OO-JX-17
'-------i--t--o .....
ANT
AVC (MASTER)
H'c
V IFO)BFd
)
AUDIO
OUTPUT
H-F-O
COUTPUT
-----11-----+--... .... 0 AN T
SP-600-J X-I?
(SLAVElV
j
AUDiO
OUTPUT
AVC
cH
() C
IFO BFO
!----------TO HEADSET MONITOR
RADIOTELETYPf
TERMINAL
EQUIPMENT
TELETYPE-
WRITER
UNIT
figure 4-2. frequency-shift Space Diversity, A-f Output Receiving System
15

Sedion IV T.O. 3112-4-18-2
Paragraphs 4-4 to 4-8
TOOUTPVT
l£VEL METER
I-F OUTPUT
V REG
OAZ
8+ RECT
5R4GY
VIZ
V14.
VI3
_FER
Ave
IFO
r---o
6IIA6 OIl
UUOll
572.,
6C4
57491
UUWI
6_
_7
VI4A
V9 VIO VII
DETECT-
.~
IF IF
DRIVER
TOR
-
VI7
~i<l
6IIA6 OIl -
6BA6 OIl
~
6IIA6 OIl
a.
UUOll
;IIi
AF
r---
OUTPUT
j
57491
574"
57491 57251 IZAU7 5VlIGT
6BA&W
-
....-
UUWI
.cl97
VI5A
Vl51
VI6A UIIIITER IIETER
~
CATIlOIIE UUClll
UUOR
--
FOLLOWER 57261 57261
IZAU7 6AL5WI 6AL5WI
IiOlI7
6097
VI9 vie
VZO
81AS RECT
6Al.5 OR
57261
6AL-swf.
6097
ve
ose
aC4
•
V6
j
IIIXER
68E6
..
\
i~"'--""'i/<J
"\ V7 ,~
~ GATE 1
68A6 OR
57491
6BA6W
CRYSTAL
CONTROllEO
'\V7
V4
VAR
osc
6C4
~
VI
V2
Rf Rf
V5 :
-6BA6 OR
---
6BA6 OR
-MIXER
57491 57491
6BE6
6BA6W
6_
t
V3
FIXEO
OSC
6AH6
3.5 Me CllYSTAL
CONTROllED -- SIGNAL MTH c-. 10 ALL fREQUElIClES
-- -. MTH RIft DCII&.£ CilIIIV£_
---- -. MTH RlItSlIl&LE CilIIIV£_
Figure 4-3. Radio Receiver, a.oci: Diagram
the "BEAT OSC" control (18) of the master receiver
is set to ±2.55-kc knob dial indication.
e. R-F GAIN ADJUSTMENT. To provide for the
space diversity feature during reception, the gain
of
the receiver, initially receiving the stronger signal, is
reduced through use
of its "RF GAIN" control (14,
figure
1-2) so that the i-f output provided by each
receiver is approximately the same. This procedure
becomes amonitoring function during reception when-
ever either receiver does not contribute its share to
the
composite output as is the case when its meter r-f
indication is zero or continuously low compared to
that of the other receiver. Through the use of common
heterodynes between receivers, the monitoring require-
ments are facilitated and reduced to apractical mini-
mum, since relative frequency drift between receivers
is thereby eliminated.
4-4. RECEIVER FUNCTIONAL OPERATION.
4-5. BLOCK DIAGRAM. Figure 4-3 shows in block
diagram form the inter-relationships existent between
the internal circuits
of the receiver. Each block incor-
porates an electron tube,
or one section of adual tube,
as applicable. When properly installed and operated,
the receiver provides the proper signal
path for the
signal tuned in.
The receiver tuning is .accomplished
through the use
of an eight-section four-gang tuning
capacitor. The signal path through the receiver may
be traced
by referring to the block diagram. The re-
ceiver must be equipped with asuitable antenna
system to provide for the proper reception
of the
signal.
4-6. The signal tuned in is selected, amplified, and
provided with ahigh signal-to-noise ratio in VI and
V2, comprising the receiver two-stage r-f amplifier. It
16
is then heterodyned in the first mixer stage V5. V3 and
V4, respectively, provide for the fixed-frequency crystal
controlled
and variable frequency, first heterodynes of
the receiver. V3 is used for fixed-frequency crystal
controlled reception
and V4 is used to provide for con-
tinuously variable tuning.
When V3 is used the crystal
associated
with it must be suited to the desired signal
frequency.
4-7. The V5 mixer, heterodyned signal output is at a
frequency
of 455 kc for any signal frequency tuned in
on the three lower frequency bands of the receiver.
Here, the receiver single-double conversion switch (54,
figure 4-4), actuated by the "BAND CHANGE" con-
trol (6, figure 1~2), automatically assumes its single
conversion position,
to render operative and inopera-
tive, respectively,
the single and double conversion
circuitry
of the receiver. Thus for single conversion,
the signal path is by way of the V7, 455-kc i-f gate to
the input of the V9 and VI0, two-stage 455-kc i-f am-
plifier. V7 provides some amplification but its prime
function is
to provide the 455-kc signal path for single
conversion.
The V5 mixer, heterodyned signal output
is at afrequency of 3,955 kc for any signal frequency
~ed in on the three higher frequency bands of the
receiver.
Here 54 assumes its double conversion posi-
tion,
to render operative the V6 secOiid mixer and the
V8, 3.5-mc heterodyne; also,
to render V7 inoperative.
Thus for double conversion, the signal path is by way
of ~e V6 second mixer, where the 3,955-kc signal is
heterodyned
to 455 kc, to provide 455-kc input suited
to the two-stage 455-kc i-f amplifier, as before. V9 and
VI0 develop almost all of the overall gain and selectiv-
ity
of the receiver.
4-8. VII is the driver stage of ·the 455-kc i-f channel
of the receiver. It provides the 455-kc i-f signal at a
Revised 10 September 1955