LTV G133 Series User manual

·------------
GTM-0-133
TECHNICAL MANUAL
HF RECEIVER
G133 SERIES
PUBLISHED BY LTV TEMCO AEROSYSTEMS DIVISION
GREENVILLE, TEXAS
------------.------------
1 JULY 1964

GTM-D-133
TABLE OF CONTENTS
G133F HF RECEIVER
SECTION TITLE
Section I. General Description
1-1. General •••••••.•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
1-2. Equipment supplied •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
1-3. Equipment Required but not Sllpplied•••••••••••••••••••••••••••••••••••••••••••••••••••••••
1-4. Electrical Sp41citlcattona ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
1-5. Mechanical Speciftcat10!18 •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
Section U, Preparation for Use and Re•blpment
2-1. Unpacklng alJd. lnilpectlon •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
2-2. Prepa.ratton for Reshipment •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
2-3. Installation •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
Secnon m. Operation
3-1. General •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
3-2. Operating Controls ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
3-3. Operating Procedures ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
3-4. Slngle-Sldeb&M Rec eptlon ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
3-5. CW Reception ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
3-8. AM Reception •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
3-'7. Calibration •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
Section IV. Theory of Operation
Section V.
4-1. General •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••.•••••••••••••••••••••••••••••
4-2. Darlington Ampliflers ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
4-3. D.Wled 'l'h.eory of Qs>eratton.••••••••••••••••••.•••••••.••••••••••••••••••••••••••••••••••••••
4-19. Electi-ontc Pacta.ge ••••••••••••••••••••••••••••••••••••••••••.••••••••••••••••• •• • ••• ••• •• •• • •• ••
Maintenance
5-1. General ..•.•..•.••.••••••••••••••••••••••••••••••••••••.•.•••••.••••••••••••••••••••••••••••••••••••••
5-2. Power and Equipment R8q\lirementa ••••...•....••.•••.•.••..•••.•••••••••••••••.•••••.... ,,.
5-3. Preventive Maintenance •••••••••••••••••.••••.••••••••••••••••••••••••••••••••••••••••••••••••••
5-4. Daily 1Ilspectl0t1 ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
5-5. 100-Boor lllspection •••••••••••••••••.•••••••••.••.••••••••.•.••••.•...•.•••.•..••••.•••.••••...••
5-6. 1000-Hoor IIlspectlon •••••••••••••.••••••••.••••.•.•••••••••.•••••••••.••••••••••••••••..••••••.••
5-7. R-F Sensitivity Test ••••••••••••••••••••.•••.•••.....•.••....•••••...•••.•.••••.••••.•.....•••..••
5-8. Signal Monitor Output Test ................................................................... .
5-9. AM BFO Adjustment and Test .............................................................. ..
FOR OFFICIAL USE ONLY
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GTM-D-133
TABLE OF CONTENTS {CONT)
G133F HF RECEIVER
SECTION TITLE PAGE
Section V. Maintenance (Cont)
5-10. CorrecUve Maintenance •••••••••.••••.••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 5- 3
5-11. G133F Receiver Alignment Procedure•................................................... 5- 5
5-25. Gl33Dl2000-l Electronic Package Maintenance........................................ 5- 8
5-28. Megacycle Drive Chain Replacement •••••••••••••••••••••••••••••••••••••••••••••••••••••• 5- ·8
5-27. 'l'llrret Wafer Replacement.................................................................... 5-10
Section VI. ruustrated Parts Breakdown
Section vn. Scheniattcs
ii
FOR OFFICIAL USE ONLY

GMT-D-133
LIST OF ILLUSTRATIONS
G133F HF RECEIVER
TITLE
Table 1-1. G133F Tube and Semiconductor Complement. ...................................... .
Figure 2-1. G133F Critical Dimensions ........................................................... .
Figure 4-1. G133F HF Receiver Block Diagram ................................................. .
Figure 4-2. G133012000-1 Electronic Package Block Diagram ............................ ..
Figure 4-3. G133D12000-1 Electronic Package Partial Block Diagram .................. ..
Figure 4-4. Gl33D12000-1 Electronic Package Partial Block Diagram .................. ..
Figure 4-5. G133D12000-1 Electronic Package Partial Block Diagram ................... .
Figure 4-6. R-F Input Circuits, Simplified Schematic ....................................... .
Table 4-1. G133 HF Receiver Crystal Utilization ............................................. .
Table 5-1. Necessary Teat Equipment ..•...........................................................
Figure 5-1. Monitor Input Test Setup ............................................................. ..
Figure 5-2. Top Chassis, Alignment and Adjustment Locations ............................ ..
Figure 5-3. Bottom Chassis, Alignment and Adjustment Locations ....................... .
Figure 5-4. R-F and I-F Transformer Terminal Identifications ......................... .
Figllre 5-5. Trimmer Capacitor Settings ...........................•••............................
Figure 5-6. Receiver Gain Adjustment Test Setup ........................................... ..
Table 5-2. G133F TrooblesbooUng Chart ...............................................•......••..
Figure 5-6. Band Indicator .Bead Chain Stringing ............................................. .
Fig\lre 5-7. G133F AM BFO Test Circuit .............................................•..........
Table 5-3. G133F HF Receiver Slgnal I..evels ....................................•.............
Figure 5-8. Mechanical Band and TUnlng Aid Linkage, Elq>loded View ................ ..
Table 5-4. Voltage and Resistance Measurements ............................................ ..
Figure 6-1. Model G133F HF Receiver, Front and Rear View ............................. .
Figure 6-2. Model G133F HF Receiver, Top View .......................................... ..
Figure 6-2A. Model G-133B Receiver, Bottom View ........................................ .
Figure 6:.3. Model G133F HF Receiver, Bottom, Upper Right View ..................... .
Figure 6-4. Model G133F HF Receiver, Bottom, Lower Right View .................... .
Figure 6-5. Model G133F HF Receiver, Bottom, Lower Left View ..................... ..
Figure 6-6. Model G133F HF Receiver, Bottom, Upper Center View .................. ..
Figure 6-7. Model G133F HF Receiver, Bottom, Upper Left View ..................... ..
Figure 6-8. Model G133F HF Receiver, Bottom, Right Side View ...................... ..
Figure 6-9. 70K7 Oscillator ........................................................................... .
Figure 6-10. Mechanical Band and TUnlng and Tuning Linkage .......................... ..
Figure 6-11. Turret Wafers, Al and A4 ......................................................... .
Figure 6-12. Turret Wafers, A2, A5 and A6 ..................................................... .
Flg\lre 6-13. 'l'llrret Wafer, A3 ...•.........•...............................•..................•.......
Figure 6-14. Turret Wafer, A7 .................................................................... ..
Figure 6-15. Turret Wafer, AS .................................................................... ..
Figure 6-16. Turret Wafer, A9 .................................................................... ..
Figure 6-17. Turret Wafer, AlO .................................................................... ..
Figure 6-18. G133D11000-2 Mixer Assembly ................................................... .
Figure 6-19. G133F13000-1 Oscillator Assembly ............................................. .
Figure 7-1. G133F HF Receiver ..................................................................... .
Figure 7-2. G133F12000 Electronic Package Schematic ..................................... ..
Figure 7-3. Turret and R-F Section Schematic ................................................ ..
Figure 7-4. Gl33F13000-1 Oscillator Assembly Schematic ................................ ..
FOR OFFICIAL USE ONLY
PAGE
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iii

GTM-0-133
Section I
G133F
SECTION I
GENERAL DESCRIPTION
1-1. GENERAL
The G133F Receiver is a single-channel SSB-AM-
CW receiver covering the frequency range between
0.2 me and 30 me in 30 bands of 1-megacycle
width each. Twenty-eight positions of the turret
plus two positions of overtravel provide the 30 bands.
Triple conversion is used for the 0.2- to 7-mc
bands and double conversion is used for the 7- to
30-mc bands. Audio and i-f outputs are provided.
1-2. EQUIPMENT SUPPLIED
QTY
1
As Reqd
ITEM
Receiver
Mount
PART NO.
G133F00000-1
GMl9400000-1
1-3. EQUIPMENT REQUIRED IUT
NOT SUPPLIED
QTY
1
ITEM
PART NO.
DS07-7S059
Connector
1 Connector DS07-7P059
Connector UG21EU
1-4. ELECTRICAL SPECIFICATIONS
Primary power requirements, signal inputs and out-
puts, frequency range, bandwidths, and overall
system electrical specificatiODB are:
Type Reception:
Frequency Range:
Input Power Required:
R-F Input Impedance:
500-KC 1-F Output:
Matching Speaker
Impedance:
SSB-AM-CW
0.2 to 30 me in 30 one-
megacycle bands, continuous
coverage
115- or 230-volt, single-phase
50- to 400-cps ac, 125 watts
(1.09 amps); 28-volt de, 4.7
watts (168 milliamperes)
50 ohms, unbalanced
50-mv minimum into 50-ohm
load with 5-microvolt
input signal
4 or 600 ohms
Line Output
Impedance: 150
ohms unbalanced and
600 ohms balanced.
Matching Phone Patch 500 to 600 ohms
Impedance (Local):
Frequency Stability: During temperature change
from 0 to +50°C, after 20-
minute warmup, audio output
frequency will not vary more
than ±885 cps for carrier
frequencies from 2 to 7 me.
From 7 me to 30 me, stabili-
ty varies from 36 PPM ±400
cps at 7 me to 27 PPM ±400
cps at 30 me. For ±10% line
voltage variation, frequency
varies not more than ±100
cps.
Calibration Accuracy: When zeroed to nearest 100-
kc calibration point, the fre-
quency will be within ±400
cps.
Audio-Frequency
Response:
SSB
AM
Audio Output Distor-
tion (SSB Test Signal
100-Microvolt Input,
1.0-W Output):
Local
Line
Q-Multiplier Rejec-
tion Notch Depth:
Receiver Sensitivity
(Nominal):
AM
SSB and CW
300 to 2700 cps ±3 db
100 to 2500 cps ±6 db
Not more than 10 percent
Not more than 1.2 percent
Not less than 40 db
3 microvolts for not less than
10-db signal+ noise/noise (2
to 30 me)
15 microvolts for not 1e s s
than 10-db signal + noise/
noise (0.5 to 2 me)
20.2 microvolts for not less
than 10-db signal + noise/
noise (0.2 to 0.5 me)
0.6 microvolts for not less
than 10-db carrier on/carrier
off (2 to 30 me)
3.0 microvolts for not less
than 10-db carrier on/carrier
off (0.5 to 2 me)
4.0 microvolts for not less
1-1

Section
G133F
GTM-D-133
Selectivity:
than 10-db carrier on/carrier
off (0.2 to 0.5 me)
CW (at 6-db points) 300-cps bandwidth
SSB (at 3-db points) 2.4-kc bandwidth
AM (at 6-db points) 5.0-kc bandwidth
Spurious Responses:
Intern.al Spurious
Signals
Other Spurious
Responses
Image Response
Less than one microvolt
equivalent signal (above 2 me)
Not less than 80 db down
Not less than 50 db down
1-5. MECHANICAL SPECIFICATIONS
Dimensions and weight of the G133F are:
Dimensions:
Height
Width
Depth
Weight:
1-2
6-1/4 inches
18-5/16 (approx) inches.
12-7/8 (approx) inches.
26 pounda
G133F TUBE AND
SEMICONDUCTOR COMPLEMENT
SYMBOL
TYPE FUNCTION
CRITHRU INl28 PRODUCT DEMODULATOR
CR4
CRS
IN67A METER RECTIFIER
.CR6 THRU
INl69S POWER SUPPLY RECTIFIER
CRl3
CR14
IN482A
AGC RECTIFIER
CRIS
INl28 AM DETECTOR
CRl6
IN482A AGC STABILIZER
CRl7
IN67A
MUTING TRANSIENT SUPPRESSOR
CRl201
INIOOA
MIXER
CR1202
G02
ELECTRONIC SWITCH
CRl203
IN30248
!ZENER REGULA TOR
QI 2N647
SSS/CW A-F AMPLIFIER
Ql201
2Nll42
R-F AMPLIFIER
Ql202
2Nl142
AMPLIFIER
Q1203
2N1142
AMPLIFIER
Q1204
2N1142
AMPLIFIER
Ql20S
2N1142
IMPEDANCE MATOilNG AMPLIFIER
VI 6DC6
R-F AMPLIFIER
V2
6EA8
FIRST MIXER AND HF CRYSTAL
OSCILLATOR
V3
6EA8
SECOND MIXER AND 17 • .5-MC
OSCILLATOR
V4
6EA8
THIRD MIXER AND REMOTE GAIN GATE
vs, V7, 6BA6
1-F AMPLIFIERS
ANDV8
V6
12AX7
Q.MUL TIPLIER
V9
6BA6
AGC AMPLIFIER
VlO
6EA8
L·F MIXER AND L-F CRYSTAL
OSCILLATOR
Vll
5670
1-F CA THODE FOLLOWER AND AGC
CA THODE FOLLOWER
V12
68FS
SECOND LOCAL A-F AMPLIFIER
V13
6AK6
SECOND LINE A·F AMPLIFIER
V14
12AX7
FIRST LINE A-F AMPLIFIER AND FIRST
LOCAL A-F AMPLIFIER
V15(VS01) 6136
VFO
V16 6EA8
L·F MIXER AND CALIBRATION
OSCILLATOR
V17 6BA6
BFO
V18(VS02)
6136
VFO AMPLIFIER
Table 1-1

~
I
~
""'
0
;IQ
0
""'
""'
n
>
,...
c:
"'
m
0
z
,...
-<
G133F CRITICAL DIMENSIONS
3.080
t----------17.620--------------i
MOUHTIHG IHFORMA TIOH
18 •. 180 ::::
o@oo o ~ o ~llMJ]
'
I [ l © 0
@1=1
'
I
I
@oo@o o@o@o
- -
i j
I -
17.620
.280J
.562
FROHT VIEW
Figure 2- I
4-25
,466·
I
6.62 ~
.220
0
0
0
8.5---~
0 0
1.001
r-+10.00~
d I
I
I
•--il-·~ ti~
I
- 6.27---I~
~ f-12.84
SIDE VIEW
.59
I .
3.12
_-l
C> "'
- CD
W n
w =·
""' 0
:;,
C>
....
~
I
c
I
-
w
w

GTM-0-133
Section Ill
G133F
SECTION Ill
OPERATION
3-1. GENERAL
The G133F is a single-channel SSB-AM-CW receiver
covering a frequency range of 0,2 to 30 megacycles
in 30 bands of 1-megacycle width each. The G133F
contains an electronic package which is used to
prepare the internal local oscillator signals for
processing by external equipment to determine the
tuned frequency of the G133F. Both i-f and audio
outputs are provided. The audio output level may
be visually monitored by a front-panel meter. The
meter may also be used to give signal strength in-
dications.
3-2. OPERATING CONTROLS
All of the operating controls of the G133F Rec elver
are located on its front panel. The function of each
of the controls is described in the following para-
graphs.
a. POWER -- The POWER switch controls the
power to the G133 F. The positlons of this switch
are OFF, STBY, ON, and CAL. With the switch in
the OFF position, power is removed from the G133F.
With the switch in the STBY position, the receiver
ls disabled but is capable of immediate operation
when the POWER switch is put ln the ON position.
Wlth the switch in the CAL position, the G133F
KILOCYCLE dial may be calibrated as explained
in paragraph 3-7.
b. RF GAIN -- The RF GAIN control adjusts
the gain of the r-f circuits. This control is normal-
ly set for the best signal-to-noise ratio in the audio
output.
c. MEGACYCLE TUNE -- The MEGACYCLE
TUNE control selects the 1-megacycle band in
which the receiver is to operate. The selected fre-
quency band is displayed on the MEGACYCLE count-
er in the top center of the receiver front panel.
d. KILOCYCLE TUNE--The KILOCYCLE
TUNE control selects the tenth megacycle portion
of the operating frequency; the tenth megacycle is
displayed on the MEGACYCLE counter. The KJLO-
CYCLE TUNE control is also used for fine frequency
selection. Kilocycles are displayed on the KILO-
CYCLE dial on the receiver's front panel.
e. ZERO SET -- The ZERO. SET control moves
the hairline on the KILOCYCLE dial. This control
is used to set the zero lndlcation of the KILOCYCLE
dial during calibration of the receiver.
f. MODE -- The MODE switch selects the mode
of operation of the receiver. Four positions are
provided: CW, USB, LSB, and AM.
g. REJECTION TUNING --The REJECTION
TUNING control provides for suppression of hetero-
dyne interference during AM operation.
h. METER SWITCH -- The METER s wit c h
selects the type of signal indication which is display-
ed on the meter. Three positions are provided:
RF, +lODBM, and ODBM. With the meter switch
ln the RF position, the meter indicates relative
signal strength. With the switch ln the +lODBM or
ODBM position, the meter indicates the level of
the audio output signal.
i. AF GAIN -- The AF GAIN control varies
the audio output level.
j. AM BFO ON-OFF SWlTCB--The AM BFO
ON-OFF switch in the ON position applies oper-
ating power to the beat frequency oscillator. The
BFO affects the G133F Receiver in the AM mode
only.
It. AM BFO FREQUENCY CONTROL -- The
AM BFO FREQUENCY dial, when rotated, varies
the BFO frequency from 485 kc to 515 kc. The
dial is divided into numbered divisions of 1, 2, 3,
4, 5, 6, 7, 8, 9, O, and each division ls subc:livided
in increments of 50 providing a total of 500 reset
points.
3-3. OPERATING PROCEDURES
The following paragraphs outline G133F operation ln
single-sideband, continuous wave and amplitude-
modulated modes. The procedures may vary slightly
at the discretion of the operator.
3-4. SINGLE-SIDEBAND RECEPTION
When the receiver is to be operated in the single-
sideband mode, the following procedures should be
used as a guide.
a. Turn the POWER switch to the ON position.
b. Turn the MEGACYCLE TUNE control to ob-
tain an indication on the MEGACYCLE counter
corresponding to the desired frequency band.
c. Turn the RF GAIN control fUlly clockwise.
d. Move the MODE switch to USB for upper side-
band reception or to LSB for lower sideband re-
ception.
e. Tune in the desired signal using the KILO-
CYCLE TUNE control.
f. Set the AF GAIN control for a comfortable
listening level.
g. Adjust the KILOCYCLE TUNE control to
obtain the most natural sounding audio output.
h. Adjust the RF GAIN control to the position
which gives the best signal-to-noise ratio.
i. Readjust the AF GAIN control if necessary.
3-1

Section Ill
G133F
GTM-D-133
3-5. CW RECEPTION
When the receiver is to be operated iJl the CW mode,
the following procedure should be used as a guide.
a. Move the POWER switch to the ON position.
b. Turn the MEGACYCLE TUNE control to
obtain an indication on the MEGACYCLE counter
corresponding to the desired frequency band.
c. Turn the RF GAIN control fully clockwise.
d. Move the MODE switch to the USB position.
If interference is present, move the MODE switch to
the CW position for greater selectivity.
e. Tune in the desired signal using the KIID-
CYCLE TUNE control. If the MODE switch ts in
the CW position, tune for definite peak in signal
strength.
f. Turn the RF GAIN control to approximately
midrange, and adjust the AF GAIN control for a
comfortable listening level.
3-6. AM RECEPTION
When the receiver ts to be operated in the AM mode,
the following procedure should be used as a guide.
a. Move the POWER switch to the ON position.
b. Turn the MEGACYCLE TUNE control to ob-
tain an indication on the MEGACYCLE counter
corresponding to the desired frequency band.
c. Turn the RF GAIN control fully clockwise.
d. Move the MODE switch to the AM position.
e. Tune in the desired signal using the KIID-
CYCLE TUNE control.
f. Set the AF GAIN control for a comfortable
listening level.
g. Adjust the KILOCYCLE TUNE control to ob-
tain the best reception.
h. Adjust the RF GAIN control to obtain the
best signal-to-noise ratio.
i. Readjust the AF GAIN control if necessary.
An interfering heterodyne may be suppressed by
adjusting the REJECTION TUNING control for
minimum interference.
3-2
Note
When an interfering signal is present during
AM reception, the resulting heterodyne may
be suppressed by either of two settings of
the REJECTION TUNING control. Select the
REJECTION TUNING setting which gives
the better intelligibility. The operating
range of rotation for the REJECTION TUN-
ING control ts 180 degrees. Do not force
the control at the OFF position; no OFF
position detent will be detected.
If interference or selective fading is present, better
reception of AM signals may be obtained by moving
the MODE switch to either the USB or LSB position,
zero beating the desired carrier, and proceeding
according to steps f, g, and h in paragraph 3-4.
Choose the MODE switch position which results in
better reception.
3-7. CALIBRATION
When the G133F is being calibrated, the following
procedure should be used.
a. Move the POWER switch to the CAL position.
b. Move the MODE switch to the USB or LSB
position.
c. Tum the KILOCYCLE TUNE control to obtain
an t.ndication of 0 kc on the KIIDCYCLE dial. ('Ibe
MEGACYCLE counter and tenth MEGACYCLE count-
er reading should approximate the desired fre-
quency of operation.)
d. Tune the KILOCYCLE TUNE control to ob-
tain a zero beat.
e. Using the ZERO set knob, move the hairline
to 0 on the KILOCYCLE dial.
f. Retum the POWER switch to the ON position.

GTM-D-133
Section I
Gl 33
SECTION IV
THEORY OF OPERATION
4-1. GENERAL
The G133 F Receiver is shown in block diagram
form in figures 4-1 and 4-2. The Gl33F covers the
frequency range from 0.2 to 30 megacycles. Both
double-conversion and triple-conversion are used.
Triple-conversion is used for the 0.2-mc to 7-mc
bands, and double-conversion is used for the 7-mc
to 30-mc bands. For 7-mc to 30-mc operation the
14.5-mc to 15.5-mc bandpass network and second
mixer are bypassed.
The Gl33F utilizes a built-in low frequency con-
verter to tune frequencies below 2 me. The tuning
mechanism, counter dials, and turret are arranged
so that the two lowest bands, 0.2 to 1 me and 1 to
2 me, use the 28-mc to 29-mc and the 29-mc to
30-mc bands of the receiver as a variable i-f
(conversion) frequency. As the MEGACYCLE count-
er is reduced in setting below 2 me (lowest band
on the turret), a segment switch S6 connects the
low frequency converter and its low pass filter be-
tween the antenna and the turret input, which is now
the 29-mc to 30-mc band. When the MEGACYCLE
counter setting is reduced below 1 me, the seg-
ment switch S6 maintains the low frequency con-
verter connection, but the turret is changed to the
28-mc to 29-mc band. In this· manner, the 28
positions of the turret plus the two positions of
overtravel provide 30 frequency bands, each I-mega-
cycle wide. The 0.2-mc limitation of the lowest
band is a !unction of the frequency rolloff in the
low pass filter and low frequency losses in the
mixer. ·
The electronic package of the Gl33F is shown in
block diagram form in figure 4-2. This assembly
prepares the local oscillator frequencies of the re-
ceiver for processing by external equipment to ac-
curately determine the tuned frequency of the G133F.
During receiver operation in the first seven fre-
quency ranges (0.2- 7 me), the output of the high
frequency crystal-controlled oscillator is mixed
with the output of either the 17.5-mc oscillator or
the low frequency crystal-controlled oscillator (de-
pending on which one is in use), and the resulting
mixed frequency is applied to a notch filter (see
figures 4-3 and 4-4). The notch filter attenuates
the basic crystal oscillator frequencies of 8.5, 9.5,
and 10.5 me of the receiver which appear in the
mixer output. These frequencies closely approximate
the desired output frequency during some receiver
operating modes and must therefore be suppressed.
The notch filter has lumped constant components
which attenuate all frequencies above 9.5 me so
that they will be suppressed in the output. During
operation in the remaining 23 frequency ranges
(7- 30 me), the low frequency crystal-controlled
oscillator and 17.5-mc oscillator are off, and the
output of the high frequency crystal-controlled oscil-
lator goes through the by-pass circuit to the elec-
tronic switch. The output of the electronic switch is
amplified and applied to output jack Jl 101 of the
electronic package. The output of the variable fre-
quency oscillator, which functions during operation
in all 30 bands, is applied through a Darlington
amplifier to output jack J1102 of the electronic
package. The outputs of J1101 (3 to 32 me) and J1102
(2.5 to 3.5 me) are routed to external equipment
which accurately determines the Gl33F tuned fre-
quency. The G133F13000-1 Oscillator Assembly pro-
vides BFO operation in the AM mode.
4-2. DARLINGTON AMPLIFIERS
There are four Darlington amplifiers in the elec-
tronic package, one for the output of each receiver
oscillator. The Darlington amp l if i e r is a twv-
transistor, cascaded emitter follower (see figure
7-2). Each amplifier provides more than 60-db
decoupling between output and input. Because of
the amplifier's low output impedance, the output
voltage and waveforms are not affected by cable
lengths 25 feet or less. The Darlington ?..mplifiers
are encapsulated in epoxy resin to provide protec-
tion against moisture, heat, and mechanical damage.
The encapsulated circuits are shown in enclosures
on the schematic of the electronic package, figure
7-2.
4-3. DETAILED THEORY OF
OPERATION
A detailed description of the operation of the circuits
of the G133F Receiver is given in the following
paragraphs. Figure 7-1 is a schematic diagram of
the G133F Receiver.
4-4. R-F INPUT TUNING
Signals from the antenna are applied to connector
J106 and are routed through switch S6 to imped-
ance-matching transformer l..30. The output of L30
is coupled to the first section of the double-tuned
input network (see figure 4-6). The double-tuned
input circuits are composed of capacitors C40 and
C71; chokes l..33, l..32, L31, L69, L68, L67; and the
detailed parts mounted on turret wafers Al through
A5. All r-f section detailed parts and turret wafers
4-1

SEE
NOTE
I
ANTENNA > 0.l TO 30.0 MC
T of
d--~
• I
I
l.O MCI
I
CALIBRATION
osc
100 KC
Vl68
)>6UIA
I
I
I
L__
XT AL RF OUT VFO OUT
•
t +
G133012000-1
EL ECTllONIC PACKAGE
ISEE FIGURE 4-2)
•
13-2 MC
A A
EXTERNAL
TUNER
..
18
THIRD MIXER
vu..
'16UBA
~OU~UT
2.0 TO 30 MC-.
LOW PASS
Fil TER FLI
0.2 TO l.O MC
IF AM
TRANSFORMERS
Tl•, Tl5, SKC
r--
LOW FREQUENCY
MIXER
VIOA V16A
"6U8A '"6U8A
28.0 MC
LF XTAL DSC
VI08
'"6U8
..
3-2 MC
28.2 TO
30.0 MC
I
I
I
I
J_
SIDETONE >-+
.oGC/RF GAIN
IF AMPL
Q.MIJL TIPL!ER
vs
V6
6BA6
llAX7
..
500 KC
• r
-'-~ -r
- ~K=-
/
_ ....
LSB
I I I ~
J..5 TO
l.5 MC
I I
I
~
l
I
J.5 TO l.5 MC
""'
....
0
LSB
MECHANICAL
FU FILTER
~
LSB l.• KC
MECHANICAL I
FLJ FIL TEA:
use 2., KC
---
---
CRYST Al-
I
Fl4 FILTER:
CW 300CPl
l
0
USB
'
0
cw
•
VFO AMP•
V 18 (V50l)
Vl5 (V501)
6136
6136
3.0 TO 2.0 MC VIF -.
DOUBLE A
SINGLE
TUNED
R·F CIRCUITS
IN TURRET
FIRST
MIXER
1 I~; 17-30
7-l'.l MC TO MC
14.5 TO IS.5 MC 15.5 SECOND
TUNED
R-F Cl~UITS
IN TURRET
CATHOOE
FOi.LOWER
VllB
'15670
RF AMPL
VI
60C6
---.
AGC/RF
GAIN
AGC
RECTIFIER
1'"82A
CR1'
t
i---.
._
REMOTE
GAIN GATE
Volll
"'6UIA
1---t VlA
"'6U8A
1
BANDPASS MC MIXER
FILTER VJA
Tll, Tl3 "'6U8A
I I
I I
HF XTAL OlC I 17.5 MC osc I
V18 VJB
"'6UBA I "'6UBA
-- - SE~El __ _j_ - -- -- -- -- - -- - _J
REMOTE GAIN
i.<CONTROL
IF
OUTPUT~
AGC
AMPLIFIER
V9
6BA6 • •
•
IF AMPL
V7
6BA6
CATHODE
FOLLOWER
V llA
'15670
I " I •
~
•
IF AMPL
v8
6BA6
-
...
SOO KC
SSB/CW _
I 9_...
I --.
-,---
- __ _j_ _ .. _ -
' OFF
.-Y :...M BFO
J_ ON
NOTES:
~--- .....
G133F13000.I
OSCILLATOR
SI DETONE
PRODUCT
DEIO:DULATOR
CRl THRU CR•
<•I lNllB
---
l. JUMPER REMOVED WHEN USING EXTERNAL LOW FREQUENCY Tl>i!ER.
~
--
2. SEE T ASL E 4.. 1 FOR XT AL FREQUENCIES. XT Al FREQUENCIES DOUBLED FOR OPERATION
O.l-l.O MC ANO 14.0-JO.O MC (INCL). F'-"'OAMENTAL XTAL FREQUENCY USED FOR 2.0
THROUGH I4 MC.
•3, 70K-4 OSCILLATOR COMPONENTS SHOWN, 70K·7 OSCILLATOR OPTIONAL.
- 3-l .....
-
AM(S5B
SSB/CW
AF PREAMPL
QI
2N60
AM
I
I
--
---
BFO
Vl7
6BA6
500 KC
AM DETECTOR
CRIS
IN128
1 AUDIO
AF
IST LOCAL
H
AF AMl'L
Vl'8
'112AX7
IST LINE
AF AMPL
v1 ...
l\llAX7
Figure 4-1
2ND LOCAL
AF AMPL
Vil
6BFS
lND LOCAL
AF AMPL
Vil
6AK6
METER
RECTIFIER
CRS
TRIPLE· TUNED
VARIABLE l·F
TUNED CRKTS
L 102, L 103, L IOI
3-l MC
•
AUDIO
I .. (OUTPUT
LOCAL
AUDIO OUTPUT
I ... ( 6000HM
BALANCED LIN!
14--
Section IV
Gl33F

r-
GTM-D-133
Section IV
Gl 3 3F
G133D12000-1 ELECTRONIC PACKAGE, BLOCK DIAGRAM
HF XTAL OSC
17.5 MC OSC
V2B
V3B
-
-·- ---
---~--
DARLINGTON
DARLINGTON
AMPLIFIER
AMPLIFIER
A1201
A1202
It
AMPLIFIER
Q1201
RECTIFIER -
CR1201
-
'
AMPLIFIER·
~
LC FILTER
Q1202
LF XTAL OSC
VlOB
-
-- -- -- - - -
DARLINGTON
AMPLIFIER
A!203
VFO
VIS (V501)
---~--- -,
DARLINGTON
I
AMPLIFIER
A1204
I
I
I
~
T
I
I
ELECTRONIC
~·
J1102
2.5-3.5 MC
VAR.OUT
C1105
BY-PASS
-
ii--
SWITCH
CIRCUIT
CR1202
NOTCH FILTERS
THREE-STAGE
~ -
AMPLIFIER
FL1201 FL1202
Q1203 Q1204 Q1205
~·
C1106
I
J..
J1101
3.0-32.0 MC
OUT
l
L------------------ ____________ .J
G133D12000-1 ELECTRONIC
r-
1
I
I
I
r
I
I
I
I
I
I
I
-
HF XTALOSC
V2B
-·!i_
-
DARLINGTON
AMPLIFIER
A1201
RECTIFIER
CR1201
•
AMPLIFIER
Q1202
- - -
--
AMPLIFIER
Q1201
-
-
LC
...
FILTER
r-
Figure 4-2
PACKAGE, PARTIAL BLOCK DIAGRAM
LF XTAL OSC
VFO
VlOB
V15(VS01)
-
-·!!._
----f' -
DARLINGTON
DARLINGTON
AMPLIFIER
AMPLIFIER
A1203
A1204
THREE-STAGE
NOTCH FILTERS
FL1201, FL1202
r--.
AMPLIFIER
Q12t15 Ql)04 Q1205
-
-,
I
,....
fJ T
I
I
I
I
I
I
I
I
~
I
Jl 102
2.5-3.5 MC
VAR.OUT
J1101
3.0 OR 4.0 MC
OUT
L Eq::on~f
1
~ • ~Pr~~ I signal _
__________ _J
4-3

Section IV
G133F
GTM-D-133
G133D12000-1 ELECTRONIC PACKAGE, PARTIAL BLOCK DIAGRAM
HF XTAL OSC
17.S MC OSC
VFO
V2B
VJB Vl5(V501)
f,
f2 fJ
r
I - -
-· - -----
- --
--- --
-
--
------,
I
I
DARLINGTON
AMPLIFIER
A1201
RECTIFIER
CR1201
~
AMPLIFIER
DARLINGTON
AMPLIFIER
Al202
•
AMPLIFIER
Q1201
_...
LC
I
Q1202
FILTER
L!:: _______ _
Equation: -f1 +f2 -f3 +.5(Preat) =f 1i91141I
I
I
DARLINGTON
f,
I
AMPLIFIER
A1204
,
I
I
I
I
I
NOTCH FILTER
THREE.STAGE
fz .f I
-
~
AMPLIFIER
FL 1202
Q1203 Q1204 Q1205
-------- -__ ___.
Figure 4-4
J1102
2.5-3.5 MC
VAR.OUT
JllOI
5.0.9.0 MC
OUT
G133012000-1 ELECTRONIC PACKAGE, PARTIAL BLOCK DIAGRAM
4-4
HF XTAL OSC
V2B
f1 or 2f1
r--- --
11 DARLINGTON
AMPLIFIER
I Al201 AMPLIFIER
L-----..-.. Q1201
I
L __ _
BY-PASS
CIRCUIT
Equation: ·f, + f2 ·1
1 +
.S(Preset) =f signal
VFO
V15(VSOI)
DARLINGTON
AMPLIFIER
A1204
-- .,
I
I
I
h J1102
.__---~0 2.5-3.5 MC
VAR.OUT
r;.'EL";,EC~T;;RON;:;;:;;;:IC~t---... C1105
t4'--I SWITCH
CR1202
._.. _ __. Cll06
....._ __ _
THREE-STAGE
AMPLIFIER
Q1203 Q1204 Q1205
Figure 4-5
f1 or 2f1

GTM-D-133
Section IV
G133F
R-F INPUT CIRCUITS, SIMPLIFIED SCHEMATIC
ANT.
C40
J
Jl
LJO
":"
-'' '
"':"
Ien
Lm
/
/
/
/
L67
":"
RF AMPL
VI
":"
SEE
'-- -,
-../
SEE
NOTE NOTE
1
I
I
NOTES:
I
1. SHORTED OUT ON 2 MC BAND.
":"
0
SWITCH IS PART OF TURRET
-
WAFER.
2. Cp IS ON WAFER Al.
L KILOCYCLE
TUNE
_J
Lp IS ON WAFER A2.
-- - -
Lm IS ON WAFER A3.
Cn IS ON WAFER A4.
figure 4-6
Ln IS ON WAFER AS.
are shown in figure 7-3. The first section of this
network is tuned by capacitors C40 and Cp and
chokes 1.p-Lm, L.13, L.12, and L.11. For any position
of the turret, L.13, L.12, L.11, and C40 are in the
circuit, and the band changing is accomplished by
connecting the proper turret-mounted components
into the circuit. The tuning slug of L32 is mechani-
cally coupled to the KILOCYCLE TUNE control of
the receiver, and the position of the slug is varied
to accomplish tuning throughout the megacycle fre-
quency band which is selected by the MEGACYCLE
TUNE control. The second section of the network is
tuned by capacitors C71 and Cn and chokes I.n-Lm,
L69, L68, and 1117. The tuning slug of 1118 is gang-
ed to the KILOCYCLE TUNE control of the receiver
to accomplish tuning in the same manner as that of
L.12 in the first section of the network. The turret-
mounted detailed parts are selected by the MEGA-
CYCLE TUNE control. This control positions the
turret wafers so that the proper set of detailed
parts is connected into the circuit for the desired
1-mc band. Coupling between the two sections of the
input network is provided by mutual inductance Lm.
The output network consists of a single-tuned cir-
euit using a band-switching and tuning arrangement
similar to that of the input network.
4-5. FIRST MIXER
The output signal of r-f amplifier Vl is applied to
the grid of the first mixer V2A, while the h-f
crystal-controlled oscillator signal is injected at
the cathode. The output network consists of a 14.5-
mc to 115.5-mc bandpass filter for 2-mc to 7-mc
operation and a· 3-mc to 2-mc variable, triple-
tuned network for a 7-mc to 30-mc operation. The
slugs of the 3-mc to 2-mc variable i-f network
inductors are mechanically coupled to the KILO-
CYCLE TUNE control of the receiver and are track-
ed with the slug-tuned indicators in the r-f circuits
to produce the 1-mc coverage for each band.
4-6. SECOND MIXER
During 2-mc to 7-mc operation, second mixer V3A
uses a 3-mc to 2-mc variable i-f circuit for its
output network. This is the same output network that
is used by the first mixer during 7-mc to 30-mc
operation. The signal from the first mixer plate is
passed through the 14.5-mc to 15.5-mc bandpass
filter network, T12 and T13, to the grid of the second
mixer. The 17.5-mc oscillator signal ls injected
into the cathode circuit of this mixer. The second
mixer is inoperative during 7-mc to 30-mc op-
eration.
4-7. THIRD MIXER
The third mixer, V4A, receives its input signal from
the 3-mc to 2-mc variable i-f network. The output
signal from the first or second mixer is applied to
4-5

Section IV
G133F
GTM-D-133
the grid of the third mixer, and the VFO signal is
injected into the cathode of the third mixer. An
external VFO signal may be injected through con-
nector J6 if external frequency control is desired.
The third mixer produces the final fixed i-f of 500
kc. Part of the 500-kc i-f signal is applied from the
screen of V4A to connector Jl07. The signal at J107
is suitable for an input to the spectrum display
equipment.
The output network of the third mixer is selected
by the MODE switch on the front panel. Filter FL2
is used for I.SB operation, and filter FL3 is used for
USB operation. These are mechanical filters which
provide a 2.4-kc bandwidth. The CW position of the
MODE switch selects a crystal filter FL4. This
crystal filter provides a 300-cps bandwidth. The AM
position of the MODE switch selects a network,
composed of two loosely-coupled 500-kc i-f trans-
formers T14 and T15, which provides a bandwidth
of 5-kc.
4-8. FIRST 1-F AMPLIFIER
The first i-f amplifier V5 receives its input signal
from the third mixer through one of the four selec-
tive networks described in paragraph 4-7. The output
signal is coupled to the Q-multiplier through i-f
transformer Tl.
4-9. Q-MULTIPLIER
The Q-multiplier V6 uses a twin triode. The first
triode section is a cathode follower, the output of
which is coupled to the cathode of the second triode
section. When REJECTION TUNING is being used, the
signal ,from the plate of the second triode is coupled
through a parallel-tuned circuit to the grid of the
second i-f amplifier V7. The parallel-tuned circuit
consists of choke LlOB, capacitors C145 and Cl46, and
a small trimmer capacitor. These parts, plus resis-
tors R33 and R34, form a bridged-T rejection notch
filter. The output of the parallel-tuned circuit is also
coupled to the grid (pin 7) of the second triode. This
feedback arrangement forms a Q-multiplier. The Q
of LlOB is 250. The feedback loop has a gain of 10,
resulting in an overall Q of 2500 and a rejection
notch depth of not less than 40-db. By turning t he
REJECTION TUNING control fully counterclockwise,
the bridged-T network is shorted, deactivating the
rejection filter.
4-10. SECOND 1-F AMPLIFIER
The second i-f amplifier V7 receives its input
signal from the Q-multiplier network. The output
network of the second i-f amplifier is i-f transform-
er T2. The secondary of T2 is coupled to the third
i-f amplifier VB and cathode follower VllA.
4-6
4-11. THIRD 1-F AMPLIFIER
The third i-f amplifier VB receives its input signal
from the second i-f amplifier through i-f trans-
former T2. The third i-f amplifier output is coupled
to the product demodulator through i-f transformer
T3 and to the AM detector through capacitor C15B.
4-12. PRODUCT DEMODULATOR
The product demodulator is composed of CRl, CR2,
CR3, and CR4 in a diode-ring configuration. The
signal from beat-frequency oscillator, Vl 7, is in-
jected into the product demodulator at the junction of
resistors R135 and Rl36. The B~ supplies a re-
inserted carrier in the place of the carrier missing
from the SSB suppressed carrier signal, but the
reinserted carrier is cancelled in the product de-
modulator, leaving only the recovered audio signal
in the output. The audio output of the product de-
modulator is applied to SSB/CW AF preamplifier Ql.
4-13. SSB/CW AF PREAMPLIFIER
The output impedance of the product demodulator is
approximately 600 ohms. Transistor Ql pro:vides
impedance match and gain between the product de-
modulator and the following audio amplifier grid
circuit. The SSB/ CW AF preamplifier is an NPN tran-
sistor, connected in a common emitter configuration.
Audio signals from the product demodulator and side-
tone signals from cathode follower VllB are coupled
to the base of Ql. The SSB/CW AF preamplifier
output signal is coupled from the collector of Ql
through capacitor Cl65 to switch S2C. During SSB
and CW operation, the contacts of S2C connect the
audio output signal to the first local a-f amplifier,
V14B, and the first line a-f amplifier, V14A.
4-14. AUDIO AMPLIFIER
The audio amplifier of the G133 F consists of
electron tubes V14A and V13. The first audio ampli-
fier, V14A, receives its input from SSB/CW AF pre-
amplifier Ql or from AM detector CR15; depending
upon the position of MODE switch S2. V14A is a
voltage amplifier which drives the second audio
amplifier V13. The plate load of V13 is transformer
T4, which provides audio output impedances of 150
ohms and 600 ohms. Distortion is reduced by the
use of negative feedback from transformer T4 to
the cathode of V14A.
4-15. LOW FREQUENCY MIXER
For receiving signals in the 0.2-mc to 2-mc range,
the G133F uses low frequency mixer VlOA and Vl6A

GTM-0-133
Section IV
G133F
4-17.G133F13000-1 BEAT FREQUENCY
OSCILLATOR
to convert the signal for reception on the receiver
28-mc and 29-mc bands. The low frequency input
to the mixer is passed through a low-pass filter,
and the output of the mixer is tuned by the turret
and slug-tuned circuits.
4-16. OSCILLATORS
Calibration oscillator V16B is a crystal~ontrolled
oscillator operating at 100 ldlocycles. Variable ca-
pacitor C227 trims the frequency of the oscillator.
The output of the calibration oscillator is coupled
to the antenna jack J106. Harmonics of this oscil-
lator will cause beat notes in the audio output at
the 100-lcc points of the G133F tuning range. These
beat notes are used for the calibration of the KILO-
CYCLE dial as outlined in Section m. The calibra-
tion oscillator is able to make this calibration only
when POWER switch Sl is in the CAL position.
Low frequency crystal-controlled oscillator VlOB
uses a 14-mc crystal. The plate circuit of this
oscillator is tuned to the second harmonic of the
crystal. The low frequency crystal-controlled oscil-
lator operates only when G133F is receiving signals
in the 0.2-mc to 2-mc band8. The output of this
oscillator is coupled to low frequency mixer V16A.
Capacitor C2 trims the crystal to frequency.
High frequency crystal-controlled oscillator V2B op-
erates on all bands. The frequency of oscillator
operation is dewrmined by one of 16 crystals
mounted on a wafer in the turret (see table 4-1).
Crystal selection is automatically performed during
setting of the MEGACYCLE TUNE control. Indi-
vidual turret-mounted piston trimmer capacitors
trim each crystal to frequency.
The 17.5-mc oscillator, V3B, is crystal controlled.
This oscillator operates only when the G133F is
operating in the 2-mc to 7-mc range. Capacitor
C233 trims the crystal to frequency.
The variable -frequency oscillator is a Collins 70K-
4 permeability-tuned oscillator. The frequency of
this unit is varied by changing the inductance of
L501. This change of inductance is accomplished by
turning the KILOCYCLE TUNE knob, which is coupled
mechanically to the slug of L501. The output of
oscillator tube V15 (V501) is coupled to isolation
amplifier V18 (V502). The isolation amplifier is
coupled to the cathode of the third mixer through
transformer T501.
The beat frequency oscillator (BFO) Vl 7 is a 500-
kc crystal-controlled oscillator which operates only
when the MODE switch is in USB, LSB, or CW
position. The BFO is not for AM operation. Output
of the BFO is coupled to the product demodulator.
The G133F13000-1 Oscillator Assembly, with a funda-
mental center frequency of 500 kc, operates in the
AM mode only. An ON-OFF switch mounted on the
receiver front panel is used to connect +28-volt,
d-c power to the oscillator. A helical potentiometer,
also mounted on the receiver front panel, is used to.
vary the oscillator frequency up to a maximum of
±15 lee from the 500-kc center frequency. The
potentiometer dial is divided into 10 divisions
numbered 1, 2, 3, 4, 5, 6, 7, 8, 9, O; subdivided into
50 divisions each. Rotating the knob so that the
large needle rotates ±five revolutions from the
center setting of the potentiometer constitutes the
maximum frequency variation of ±15 kc that is
possible. When the AM BFO ON-OFF switch is
turned on, the +28-volt, d-c power is supplied to
the filter aection of the BFO through resistor R1301.
Resistor R1302 adjusts the working voltage of the
BFO frequency potentiometer for the purpose of
aligning the center of the potentiometer to coincide
with the 500-lcc i-f center frequency of the receiv-
er. Variable capacitor C1307 is used to adjust the
resonant frequency of the tank circuit to assure that
the center frequency of the BFO is at the desired
500-kc setting prior to adjustment of R1302. The
potentiometer varies the voltage to the variactors
CR1302 and CR1303 that are across the tank circuit
comprised of coil L1301, capacitor C1304, and
variable capacitor C1307. The capacitance of the
variactors varies with the amowit of the bias volt-
age applied to the variactors.Varying the capacitance
of the variactors varies the resonant frequency of
the tank circuit from the 500-lcc center frequency.
The output of the tank circuit is applied to the oscil-
lator transistor Q1301. Resistor R1307 decreases
the Q of the tank circuit comprised of coil L1304
and capacitor C1309 that is used to develop a feed-
back voltage to the oscillator through capacitor
C1305. The tank circuit comprised of coil L1305
and capacitor C1311 is used as a harmonic sup-
pressor for all harmonics and allows only the
fundamental frequency at the BFO output to be ap-
plied to the AM detector of the receiver. The tank
circuit comprised of coil L1303 and capacitor C1308
forms a decoupling network which is connected to
the AM position of the receiver mode switch. When
the receiver mode switch is placed in the AM posi-
tion, the BFO decoupling network is connected to
ground. This furnishes a d-c path to the emitter of
transistor Q1301 permitting operation of the oscil-
lator. This assures that the BFO operates only in
the AM mode.
4-18. SPECIAL CIRCUITS
Cathode follower V11A receives i-f excitation from
the second i-f amplifier. The output of this cathode
4-7

Section IV
G133F
GTM-D-133
follower is applied to automatic gain control (AGC)
amplifier V9. Output of the AGC amplifter ls coupled
to the AGC rectifier CR14 and through the low-
pus tuter to the t-f output connector J105.
AGC rectifier CR14 rectifies the t-f signal from the
AGC amplifier V9. The d-c output from the AGC
rectifter ls used for automatic gain control of the
r-f and t-f amplifiers.
The sidetone output of an associated system trans-
mitter may be connected to connector JS. This
allows audible monitoring of transmission. The
sidetone signal is applied to cathode follower VllB.
The output of VllB is applied to SSB/CW/AF pre-
amplifier Qt and then to the audio amplifier.
Diode CR16 in the grid return circuit of r-f ampli-
fier V1 is used to stabilize the AGC circuit by
preventing oscillatory action in the AGC loop.
Diode CR17 stabilizes the r-f gain control bua by
suppressing transients which occur during mute
on-off switcbing.
Remote gain gate V4B presents a btgb-impedance
isolation between the remote gain line and the AGC
circuit. This prevents the low-impedance remote
gain circuit and the bias supply from loading the
high-impedance AGC circuits.
4-19. G133D12000-1 ELECTRONIC
PACKAGE
A detailed description of the operation of the cir-
cuits of the electronics package is given in the
following paragraphs. Figure 7-2 is a schem1Ltic
diagram of the electronics package.
4-20. OPERATION IN THE 0.2- TO
2.0-MC TUNING RANGE
During operation in the 0.2- to 2.0-mc range, both
the low frequency crystal-controlled oscillator and
the high frequency crystal-controlled oscillator are
operating (see figures 4-3, 7-1, and 7-2). The out-
put of the low frequency oscillator is applied through
J1104 of the electronic package to Darlington
amplifier A1203, which provides 60-db decoupling
between the oscillator and amplifier Q1201. The
high frequency oscillator signal is applied through
Jll03 of the electronics package to Darlington
amplifier A1201, which provides 60-db decoupling
between the oscillator and amplifier Q1201. The
high frequency output of A1201 and the 28-mc out-
put of A1203 are linearly mixed in the base circuit
and then amplified by Q1201.
When the low frequency oscillator is operating, a
B+ voltage is applied through C1106 and R1226 to
the anode of CR1202. This positive voltage forward
4-8
biases CR1202, preventing the output of Q1201 from
being coupled to Q1203 through C1206, C1207, and
R1216; C1209 and R1219, C1211, and C1220. When
CR1202 is forward biased, the output of C1207
is shorted to ground.
The output of Q1201 is coupled through C1202 to
CR1201 which rectifies the signal. This rectified
signal is applied to amplifier Q1202. Q1202 ampli-
fies the signal to help overcome the loss in the
following ftlters. The LC tuter (consisting of L1202
through L1204, C1210, and C1212 through C1217),
FL1201, and FL1202 prevent the fundamental and
sum frequencies of the high frequency and low fre-
quency oscillators from appearing at the base of
Q1203. The output of the filter network ts the dif-
ference frequency signal between the high frequency
oscillator and the low frequency oscillator.
During operation in the 0.2- to 1-mc frequency
range, the high frequency oscillator operates at
31 me. The low frequency oscillator frequency is
28 me; therefore, the difference in frequency is
3 me.
During operation in the 1- to 2-mc frequency range,
the high frequency oscillator operates at 32 me. The
low frequency oscillator frequency is 28 me; there-
fore, the difference in frequency is 4 me.
The output of the filters is applied to voltage ampli-
fiers Q1202, Q1203, and Q1204 which amplify the
signal. The signal is then applied to J1101 of the
electronic package.
4-21. OPERATION IN THE 2- TO 7-MC
TUNING RANGE
During operation in the 2- to 7-mc tuning range,
the 17.5-mc oscillator and the high frequency oscil-
lator are operating, with the low frequency oscillator
disabled. (See figures 4-4, 7-1, and 7-2.)
The 17.5-mc signal is applied to J1105 of the
electronic package and then through Darlington
amplifier A1202 to the base of transistor Q1201.
The high frequency output of A1201 and the 17.5-
mc output of A1202 are linearly mixed in the base
circuit and then amplified by Q1201.
When the 17.5-mc oscillator is operating, a B+ volt-
age is applied through Cll05 and R1225 to the anode
of CR1202. This positive voltage forward biases
CR1202, shorting the output of C1207 to ground.
The signal must therefore go through Q1202 and the
filter network.
The output of Q1201 is rectified by CR1201 and
applied to Q1202. Transistor Q1202 amplifies the
signal to help overcome the loss in the following

GTM-D-133
Section IV
G133F
G133F HF RECEIVER CRYSTAL UTILIZATION
RECEIVER
FREQUENCY
TURRET CRYSTAL
17.5-MC
L-F CRYSTAL
RAHGEIH
OSCILLATOR
OSCILLATOR
MEGACYCLES
FREQUENCY (MC)
SYMBOL
(2x14 MC.28 MC)
0.2.
1.0 15.5
Y20
OFF
ON
1.0.
2.0 16.0 Y12
OFF
ON
2.0.
3.0 12.5 YI ON
OFF
3.0.
4.0 11.5 Y2 ON
OFF
4.0.
5.0 10.5 Y3 ON
OFF
5.0.
6.0 9.5
Y4
ON
OFF
6.0. 7.0 8.5 Y5 ON
OFF
7.0.
B.O
10.0
Y6 OFF OFF
B.O. 9.0 11.0 Y7
OFF OFF
9.0. 10.0 12.0
YB OFF OFF
10.0.11.0 13.0
Y9
OFF OFF
11.0. 12.0 14.0
YlO OFF OFF
12.0. 13.0 15.0
Yll OFF OFF
13.0. 14.0 16.0
Y12
OFF
OFF
14.0. 15.0 8.5
Y5
OFF OFF
15.0. 16.0 9.0
Y13 OFF OFF
16.0. 17.0 9.5
Y4 OFF
OFF
17.0. lB.O
10.0 Y6
OFF OFF
lB.O. 19.0 10.5 Y3
OFF OFF
19.0. 20.0 11.0
Y7 OFF OFF
20.0. 21.0 11.5
Y2
OFF OFF
21.0. 22.0 12.0 YB OFF OFF
22.0. 23.0 12.5
Yl
OFF
OFF
23.0. 24.0 13.0
Y9
OFF OFF
24.0. 25.0 13.5 YlB OFF
OFF
25.0. 26.0 14.0
YlO
OFF OFF
26.0. 27.0 14.5 Yl9 OFF OFF
27.0. 2B.O 15.0 Yll OFF OFF
28.0. 29.0 15.5 Y20 OFF OFF
29.0. 30.0 16.0 Y12 OFF OFF
Table 4-1
filters. The LC filters FL1201 and FL1202 pre-
vent the fundamental and sum frequencies of the
high frequency oscillator and 17.5-mc oscillator
from appearing at the base of Q1203. The output of
the filter network 1s the difference frequency signal
between the high frequency oscillator and 17.5 me.
As the frequency range of the receiver is changed
from 2 to 7 me, the high frequency crystal-controlled
oscillator output signal will vary 1n 1-mc steps
from 12.5 to 8.5 me, and the difference frequency
will vary in the same manner from 5 to 9 me.
FL1201 and FL1202 are notch filters which prtt-
vent some of the fundamenW frequencies of the high
frequency crystal-controlled oscillator (8.5 me, 9.5
me, and 10.5 me) from being passed on to the next
stage.
The output of the fUters is amplified by Q1203, Q1204,
and Q1205, and applied to J1101 of the electronic
package.
4-22. OPERATION IN THE 7- TO 30-MC
TUNING RANGE
During operation in the 7- to 30-mc tuning range,
both the low frequency crystal-controlled oscillator
and the 17.5-mc oscillator are disabled, and the
high frequency crystal-controlled oscillator is op-
erating. (See figures 4-5, 7-1, and 7-2.)
The output signal from the high frequency oscillator
is applied to J1103 on the electronic package and
then through Darlington amplifier A1201 to tran-
sistor Ql201.
4-9