RCA AR-88 User manual

1
I OD l . ·.88
INS ,TRUC IONS
.~.IIII ••• 110
........... M cturing Com y. me.;
"It. $, IVICE O~ ,H, I II:,M;UO CO.pO AT ON 0 A

PrInted In U. S. A.
GENERAL PURPOSE
COMMUNICAliONS RECEIVER
MODEL AR-88
INSTRUCTIONS
Manufadured by
RCA ManuFacturing C-ompany, Inc.
Camden, N. J., U. S. A.
"AN ReA SERVICE"
18-25921·2

TABLE OF CONTENTS
Title Page
Technical Summary.................. . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "
I Introduction... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
11 Equipment ............................................................................ 5'
III Description... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
W Circuit Arrangements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
V Performance ........................................................................... 7
VI Installation....................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
VII Operation................................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
VIII Maintenance and Alignment Procedure.................................................... 10
IX Mechanical
Construction................................................................. 13
X Parts List............................................................................. 14
XI Vibrator Power Supply Unit, MI-8319...................................................... 24
Figure
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure
10
Figure 11
Figure 12·
Figure 13
Figure 14
Figure 15
ILLUSTRATIONS
FrDnt View of AR-88 Receiver. . . . . . . . . . . . . . . . . •• . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Loudspeaker ......................................................•...............• 2'
Diagram of Rear of Chassis ......................................... '.' .............. '. 6
Diagram of Front Panel
..........................•. : '.' .......... '. . . . . . . . . . . . . . . . •. . . . 8
Diagram of Top
of Chassis .. ,. '" " ............................ ,... . ........ .........• 11
AR,88 Chassis..................................................................... 16
Top View of
Chassis................................................................ 17
Top View of Chassis -Covers Removed. . . . . . . .. . . •. . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Bottom View of Chassis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
R,FUnit ........................................................................... 19
Schematic Diagram ............•........................ :........................... 20
Selectivity Curves................................................................... 21
Fidelity Curves .............................................................. ; . . . . . . 22
AVe Curves....................................................................... 23
Vibrator Power Supply Unit ........ , ....•......... , .. ... . ... .. .......... . .. . . .. ...... 26
TABLES
Table 1 Performance Data . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Table 2 Tube Socket Voltages ...............•.............................. , ....... '" ..... . . 14
3

GENERAL PURPOSE COMMUNICATIONS RECEIVER
MODEL AR-88
TECHNICAL SUMMARY
Electrical Characteristics
Frequency Range--total 6 bands ......... , ............ , ......... , .................... 535 to 32,000 lee
Band 1 ....................•••..••....•..•..••. , ......•.....•........•• ~. "'~ ... 535 to 1,600 kc
Band 2 ......................•..••..•.............•................•. , .•.•.... 1,570 to 4,5;0 ke.
Band 3., .........•...........•.......••..•..•.••......•.•...........••....... 4,.SO to 12,150 kc',
Band 4 .....................••....•.•..........•....•...........•... ,.: ...... 11,900 to 16,600 ,kc'
Band 5 ..................................................................... 16,100 t~ 22,700 ~c
Band 6 .......................•.............•.......................•...... " 22,000 to 32,000 KC
Maximum Undistorted Output-app~ximate-2. 5 watts
Power Supply' Requirements
Line Rating .......................... 100-117, 117-135, 135-165, 190-230, 200-260 volts, 50/60 cycles.
or Batteries. '" .............................. '" 6 volt "A" battery and 250 to 3QO volt "B" battery.
or Vibrator Power Supply Unit ...............•.... MI-8319.
Tube Complement
R-F and I-P Amplifiers .......••.......•.....•...•..•..•..•.•.•••.••.•.•.....•.•• S'RCA·6SG7
1st Detector (converter) ......•............... ~ ........••.............•..... , ...• 1 RCA·6SA7
Oscillator ...........................•.... ' ................................... " • RCA-6]5
2nd Detector ................•....•.............. , .....• ' .•..........•........... 1 RCA·6H6
Noise Limiter ..............•.•...•....................•.•. '. . . . . . •• . . • •• . . . . . . .• 1 RCA·6H6
A· F Amplifier ...............••..•. ~ •••. . . . . . . . . . • . . . • •. . • . . . . •. . . . •. . . . • . •. . . .. • RCA·6S]7
Power Amplifier. . . . . . . . . . . . . •. . . . . . . . . . . . •. . . . . . . . . . •. . . . . . . . . . . . . . . •. . • . . . . . .• 1 RCA·6K6GT
Beat Frequency Oscillator .......•............•.•.•..•.••...•••.....•.•..•.......• ItllCA·6]5
Rectifier.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1 RCA·;Y3GT
Voltage Regulator . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . • ••. . . . . . .. 1 RCA· VR·. 50
*Output Impedance--2.5 ohms and 600 ohms.
Mechanical SpeciAcations
Overall Dimensions ..........•........... " ..•.• 1934 inches wide x 11 inches high x 1934 inches deep
*Receivers with Serial Nos, .below oo~ooo do not have the 600 ohm output.
TABLE 1-PERFORMANCE DATA
(Approximate Values - Taken on SampJe Receiver)
.. -
Sensitivity Antenna Input in Antenna Input in
Band inMicrovolts Microvolts
for 6 DB Microvolts for 20 DB Image
No. Megacycles for 0.5
watt . Signal·Noise Ratio Signal-Noise Ratio Ratio
1 .6 .5 .9 4.6 Greater
than
1,000.000
1.0 .9 1.4 8.0
1.5 1.0 2.2 12.0 1,000000
2
1.7
.6 1.0 5.0
240,000
3.0 .6 .95 4.8
4.3 .6 .9 4.5 14.100
3 4,6 .8 1.3 8.0 60,000
8.0 .8 1.2 6.8
11.5 .7 1.1
6,0 2,000
4
12.1
1.2 1.3 6.6 4,000
16.4
.7 1.2 7.0
1,;00
5 16.4 1.1 1.3 7.0
1,000
22';'
.8 1.4 8.0 -
..
~OO
6 22.5 2.5 1.5 8.0 400
28.0 1.2 1.3 7.0
200
I·F rejection at 600 kc is 100,000.

GENERAL PURPOSE
COMMUNICA TlONS RECEIVER
I
INTRODUCTION
In the design of a high frequency radio receiver,
there are four important qualities for consideration:
1. Usable sensitivity.
2. Selectivity.
3. Frequency Stability.
4. Reliability.
The sensitivity of this receiver is limited only by
the tube noise originating in the first tube and its asso-
ciated circuits. A large ·part· of this noise is due to
"shot" effect and thermal agitation in the first tuned
circuit. A signal, to be readable, must produce a volt:
a&-e on the grid, of the same or greate~ ordet: of mag'
I1Lt!Jde than this inherent noise voltage. Therefore, an
efficient coupling system between the antenna and the
first R,F tube of the receiver is of great importance.
This has been the subject of considerable develop"
ment, and the system used on this receiver gives opti,
mum coupling with antenna or transmission line
im'
pedances of 200 ohms, over the entire frequency
range of the receiver, except on the broadcast band.
On the broa~ast band, a low frequency primary is
used, resonating well below the band with a 200 mmf
antenna.
The second quality of a receiver, selectivity, is nec'
essarily a compromise with fidelity of the reproduced
signal. This receiver is designed to have five degrees
of selectivity, three of which include a crystal filter.'
1'0 secure good frequency stability, rugged con'
struction of parts and wiring in the high frequency
heterodyne oscillator circuit has been included in
the
design. This, together with voltage stabili2;ation of
the oscillator plate supply, temperature compensation,
and proper oscillator excitation, provides a high
de'
gree of stability.
Reliability depends to a large extent on the quality
of material and workmanship. Throughout the AR,SS
Receiver the best material obtainable is used for each
particular purpose and
all workmanship is of the best.
The following instructions should be studied before
the installation or operation
of this equipment is at'
tempted, in order that optimum performance may be
obtained.
11
EQUIPMENT
The equipment furnished consists of the Receiver
Chassis Assembly, including control panel and
tubes and cabinet for complete enclosure for table
mounting.
Additios:al equipment required includes headphones
or loudspeakers, an antenna system, and an AC sourCe
of power, batteries, or Vibrator Power Supply Unit
MI'8319.
III
DESCRIPTION
This receiver covers short wave, standard broad,
cast, and r;:,w service; its principal use is for short
wave. communications. It is designed to withstand
severe climatic and line voltage variations without
ap'
preciable impairment of performance.
Its features include: .
Mechanical Band Spread with Single Control for
ease of tuning a previously logged station.
Automatic Noise Limiter which automatically
limits interference
to a percentage of modula'
tion determined by the Noise Limiter Control.
Noise Limiter Control for setting Noise Limiter
to operate at any desired percent modulation.
Noise Limiter Switch for switching Noise Lim-
iter on or off.
Continuously variable High Prequency Tone
Control.
$
nntenna trimmer for circuit alignment.
Crystal filter for ultra'sharp selectivity when re-
quired.
Tuning meter for indicating relative strength
of
incoming signals.
Exceptionally good oscillator stability through
normal variations in line voltage.
Pour'gang Condenser giving high image ratio on
all bands.
Twelve Tuned I,P Circuits giving a very high
degrelllOf selectivity.
Temperature compensated oscillator circuits on
all bands.
Ceramic Insulation throughout on gang conden-
ser, sockets, range switch, and selectivity
switch.
Tuning Lock for service under extreme condi,
tions of vibration.

IV
CIRCUIT ARRANGEMENTS
The circuit is shown schematically in Figure 1l. It
consists of two stages of R'F amplification, first de'
tector, first heterodyne oscillator; three stages of I,P
amplification, second detector, noise limiter, second
heterodyne oscillator; A, P amplifier stage. output
power stage and power supply system.
Input Coupling - The antenna coupling.system is
designed to provide ,optimum coupling from a 200
ohm transmission line. ,except in the broadcast band.
The nrst tuned circuit is provided with a trimmer con'
denser adjustable from the front panel. This insures
for minimizing cross modulation and blocking effects
from strong iryterfering signals and for obtaining a
high degree
of image signal suppression. The amplifi'
cation is adjusted to provide optimum signal.ta-noise
ratio by making noise contributions of circuits follow'
ing the first tube negligible in comparison with the
noise contributed by the first R'P grid circuit; that
is, each tuned circuit in the receiver contributes some
noise voltage. but by making the gain of the first tube
as high as practicable, the noise contributed by suc'
ceeding circuits is unimportant.
ZERO AD.JUSTMENT
FOR
TUNING METER
ANTENNA COIL INDUCTANCE
ADJUSTMENTS FO~
FREQUENCY BANDS
VOLTAGE TAP SW. 1
0
00 01 Jc!o~-{~V!. TRAP
friVO PLUG 2.S
/
MS tt!) l
\J::!) ~U 0 T T 6 ~11~S7
~'~()-~~Tlo~~R~--~~~~--'~
~! R-e80E
6000HMS TRANSWTTER DIVERSITY. ANT.-GND.TERM. BOARD
POWER CORD RELAY
Figure 3,Diagram of Rear of Chassu
the proper tuning of this circuit with any antenna
system.
Por the standard broadcast band, conventional an-
tenna and ground connections should be used.
The antenna terminal board is provided with three
terminals (see Pigures 3 and
6), two of which may
be joined together with a link. When a single,wire
antenna is used. the link should be dosed and the
antenna connected to "A." If a ground is used, it
should be connected to "G," If a transmission line or
balanced input is used, the link should be opened and
the line connected to terminal "A" and the center
terminal. '
R.F Amplifier - The R,P AmpI1fier is designed te
provide ample selectivity ahead of the first detector
6
Band Spread- The mechanical band spread with
single control knob enables the operator to qwCHy
tune a previously logged station. The Ipg scale on the
main'dial and the separate vernier dial provide for
exact logging and tuning.
First Heterodyne Oscillator -
The first heterodyne
oscillator
is aligned to track with the R,P Amplifier
at 4H kc higher than the signal frequency, thus pro-
ducing a 45'5 kc intermediate frequency in the first
detector plate circuit which
is amplified further in the
I,P stages. The oscillator voltage is regulated by the
ReA VR·150 regulator tube to provide maximum
frequency stability under conditions of variations in
power supply voltage.

Intermediate Frequency Crystal Filter- The first
detector plate circuit is tuned to the intermediate fre,
quency and a balanced link circuit is used to couple
the first detector plate and first I,P grid circuits. A
4H kc crystal is connected in, one arm of the link cir'
cuit and a neutralizing capacitor is connected in the
other.
The impedances of the coils in the link circuit
.are designed so that the crystal selectivity character-
istic is not impractically sharp. The band width at two
times resonant input may be adjusted to 400 cycles,
1.100 cycles, or 3,000 .cycles. Por this adjustment see
"Operation." .
Intermediate Frequency
Amplifi,1!r -Three stages
of I·P amplification are used; RCA,6SG7 tubes are
used in all stages and an
RCA6H6 tube is used fof
AVC and second detector. The first I,P Transformer
has its primary and secondary tuned, and
is coupled
through the crystal filter link. The second and third
I·P Transformers are compOSE;d of four tuned circuits
each. These circuits are varied in coupling by
the
selectivity Switch. The fourth I·P Transformer has
t two tuned circuits.
• The third I·P stage is not connected to the AVC
.~ nor to the manual volume control so that a good AVC
.'characteristic with little overload distortion is ob-
tained. This also permits the CW oscillator to be
coupled to the grid circuit of this stage, giving a com'
paratively highde,tector excitation voltage with small
electrical coupling
to the oscillator circuit.
Second H~erodyne Oscillator - The second het·
erodyne (CW) oscillator is a triode RCA-6]; tube
which is electrostatically coupled to the finall-P stage.
.(\ pant;l control is provided by means'of which the
frequency of'the heterodyne oscillator and resultant
audio beat n&e may be varied.
Par:t1cular care has been taken in the design
of the
circuit constants to minimize oscillator harmonics.
Automatic Volume
Control- The AVC voltage is
obtained from the second detector, an
RCA·6H6 tube.
A variable delay is obtained depending on the setting
of the R,P gain control. .'
The second heterodyne (CW) oscillator excitation
voltage
is just lower than the A VC diode bias voltage
so that it does not decrease the sensitivity of th(
receiver.
Manual Volume
Control- Two manual volum(
controls are provided; an audio gain control which i~
employed when the AVC is in use, to obtain the de-
sired output level, and an R·P gain control.
Noise Limiter -
The noise limiter circuit utilizes
an RCA·6H6 tube and limits the noise interference te,
100% modulation and to continuously lower percent·
ages down to any modulation whatsoever, determined
by the setting of the noise Iimiter control.
A noise limiter switch in conjunction with A
VC
provides for use of the noise limiter on CWor on
modulated reception when interference
is preserit.
*Output Tube -
The RCA 6K6GT output tube is
resistance coupled from the A·P amplifier, an RCA·
6S}7 tube, and operates into an output transformer
which has taps for matching into a 2.5' or 600 ohm
load. Terminals are provided on the rear apron for
each of these load impedances.
The output from the
2.5' ohm tap is fed directly to the 2.5' ohm output ter'
minal, while the output from the 600 ohm tap is fed
to the 600 ohm output terminal through a two' position
jack mounted on the panel.
With the phone plug in'
serted into the jack in the first position, the phones
are
in parallel with the 600 ohm output and both are
on.
With the plug pushed in to the second position,
the 600 ohm output is cut off from the rear terminals.
Power Pack -
The power pack mounted on the
receiver chassis consists of a power transformer, rec'
tifier tube RCA·5'Y3GT, and filter. A tap switch is
provided on the rear apron for changing the power
transformer voltage tap. (See Pigures 3 and 6.)
The
voltage for which the switch is set may be read di,
rectly on the switch. The instrument may also be
operated from 6V. "A" and 250 to 300 V. "B" bat'
teries, or Vibrator Power Supply Unit MI,8319.
Shielding -Interstage shielding is provided to in-
sure stability under all operating conditions and to
minimize oscillator radiation. Complete external
shielding prevents coupling to any portion
of the cir·
cuit except through the antenna circuit,
V
PERFORMANCE
The performance data under technical summary
and the data for the various curves, are approximate
values taken on a sample receiver. Variations in these
values are
to be expected because of practical manu'
facturing toleran~es. The data were taken with an
artificial antenna of 200 mmf. capacity for band 1
and 200 ohms resistance for bands 2 to 6 inclusive.
The output was measured across a resistance
of 2.5'
ohms connected in place of the speaker voice coil.
The selectivity switch was placed in position
2.
• On AR·SS receivers with serial numbers below 003000, the 600 ohm outPUt is not provided. The speaker terminals on the
rear are for 2.5 ohm load, and a 20 ohm tap is provided for phones. With the headphone plug inserted into the jack in the
first poJition, the phones are in parallel with the 2.5 ohm speaker terminals and both are on. With the plug pushed in to the
lecon.d position, the speaker terminals at~ cut off and the phones are connected to the 20 ohm winding. This winding 8'ive~
luJliclent output for phones up to 2000 ohms impedance.
7

VI
INSTALLA TION
Power Supply - The power supply circuit is in'
tegral with the receiver. Determine line voltage and
frequency and check with the rating
of the receiver.
The power transformer primary may be connected
for
anyone of five voltage r3:nges by means of a tap
switch. This switch is located in the rear apron of the
receiver. and the voltage for which
it is set may be
read directly on the switch.
For Battery or other Supply Operation -For con'
nections see Schematic Diagram Figure 11. It is only
necessary to remove the plug from the socket on the
rear of the receiver, and connect the batteries to the
proper terminals as indicated by the schematic dia'
gram. A battery cable terminating'in an octal male
plug
is necessary for this purpose. A vibrator power
supply MI,8319
is available which will operate the
receiver directly from a 6 volt storage battery. For
information on this power unit
see Section XI.
Tubes -Inspect the chassis before applying power
to see that all tubes are firmly seated in their respec'
tive sockets.
Antenna -The input impedance
at the antenna
terminals
is designed to match a 200 ohm transmis'
sion line except on the broadcast band where a low
frequency primary
is used.
For general use it
is recommended that a straight
wire antenna between
25 and mfeet long be used.
Speaker Terminals for connection of a loud,
speaker are indicated in Figures 3 and
6. The output
transformer is designed to match a speaker having
2.25 ohms impedance.
Headphones - A jack is provided on the left of
the front panel for plugging in a pair of headphones.
There are two positions of the plug.
1. Half way in-for reception on both speaker
and phones.
2. Fully. in-=-for phone receptiori only.
See "CIRCUIT ARRANGEMENT" "Output
Tube."
Mounting- The instrument may be placed on a
table
or mounted on a rack. ror rack mounting loosen
the panel mounting screws and remove the front
panel and chassis complete from the cabinet.
Then
mount on rack by means of the slots at the sideS of
the panel.
VII
OPERATION
Figure 4 illustrates the three dials and eleven control knobs.
TUN'NG
VERNIER
TUNING METER
I I
I
-*-
;;.-..-
-.,. .!
--~;
•
;......f!;"
~
\ \ \1 '"
,-'''''';
\..-.::. I
~
.;... ttII .. ~
....... 1•
TONE.
~
;r;;~,
I
ANT.
TRANS.. .REe.MOD. 3
OFF • _REC-CloY. •
• ;R
~
•
TUNING
M.GAIN AUDIO GAtM SELECTIYITY
Figure 4-Diagram of Front Panel
8
J
I
•
NOISE LlMIT£R
I
SFO
M1NJlU.... • II..Y.e.. N.L.
MAN.. .1I..v.c.
NOIS!. LlMl.TI!.R
AND A.V.C.
R-8T9C

DIALS
The Main Tuning Dial is on the left and consists
of a disc with seven scales, one for each of the
six
bands and a log scale. The Standard Broadcast Band
is calibrated in kilocycles and the other five bands in
megacycles.
The Vernier Tuning Dial is in the center and has
a scale with arbitrary calibrations for exact tuning
and log records of pttrticular communication stations.
It is used in conjunction with the log scale on the
main tuning dial to
give additional figures for logging.
The Tuning Meter is on the right and is calibrated
in DB's above one microvolt.
The meter is used as a
tuning meter to indicate accuracy of tuning, and also
gives an indication of the strength of the signal being
received.
CONTROLS
Power-Transmit-Receive Switch -This is a four,
position switch. Starting from fully counterdockwise
these positions are:
1. Power off.
2. Transmit position which gives energized tube
fila\llents, open plate circuits, and shorted ter'
minals for transmitter relay on the speaker
terminal board on the back of
the chassis.
Connect relay to these
two terminals for
transmitter operation. See Figure 3.
3. Normal reception.
4. CW· reception -Beat frequency oscillator
switched on.
Selectivity Switch -This
is a five'position switch
and the band widths and control
of selectivity are
illustrated in the curves of Figure
12. The five posi,
tions are:
1. I-F band width for High Fidelity, modulated
_ reception.
2. I-F band width for normal modulated recep'
tion.
3. Crystal Filter in-for CW telegraph or sharp
modulated signal reception.
4. Crystal Filter in -for sharper CW telegraph
reception.
S. Crystal Filter in -for sharpest CW telegraph
reception.
It will be noticed that when tuningjn a modulated
signal with the crystal in. the speaker volume is greater
on either side of the point which gives the maximum
tuning meter indication.
The reason for this is that
~e carrier voltage controls the gain of the receiver
by means of the AVC circuit, and if the carrier fre,
quency is detuned slightly ftom resonance,
the gain
of
the receiver increases, so that part of the side band
frequencies are amplified very much more'
than they
are when the carrier
is tuned to exact resonance. This
is characteristic and normal for receivers with this
degree of selectivity which are provided with AVC.
Care should be taken to tune the receiver for a maxi,
mum meter indication.
The background noise and ad-
jacent channel interference will thus be materially
reduced.
Noise Limiter-A
VC Switch -This is a four·posi·
tion switch and starting from the fully counterclock,
wise position these are:
1. AVC and NL out -Manual gain only -for
CW no interference.
2. NL on, AVC out -Manual gain -for CW
with interference.
3. NL and AVC on -for Modulated Reception
with interference.
4. A VC on, NL out-for Modulated Reception
no interference.
R·F Gain Control- This continuously variable
sensitivity control is for use in conjunction with the
audio gain (Volume) control for all manual gain op-
eration. With A VC on, it should as a rule be set to
lis fully clockwise position Or may be turned to elimi-
nate interference.
Experience with
thl.. operation of this control win
add to the values obtainable from the receiver.
Noise LinUter Control -This control sets the in~
strument for operation at the required percentage
value of Noise Limitation.
The fully clockwise posi~
tion limits the noise interference to 100% modulation.
As the knob
is turned counterdockwise, the noise in~
terference is limited to continuously lower percentages
of modulation so that in the fully counterdockwise
position the Noise Limiter is operative on any modu-
lation whatsoever. Normally. the fully clockwise posi-
tion will be used, but under extreme conditions of
interference a balance point should be found for
maximum intelligibility of signal with best modula-
tion and least noise.
Tone
ContrOl- This is a continuously variable
control for reducing HF response. In the fully clock~
wise position the full tone is ,obtained and as turned
counterclockwise, high tones are lessened. Set
it to
suit the particular tonal conditions forthe signal being
received. ..'
.' .
Beat Frequency Oscillator Control -This control
is normally used for CW code signals. It gives the re-
quired audio pitch after tuning, and usually should
be set slightly off central position for the desired beat
frequency.

TUNING
For functions of controls see the foregoing para'
graphs.
1. Turn receiver on and set the Power'Transmit,
Receive Switch for the required type of
operation.
2. Set Range Switch for band required.
3. Set Antenna Trimmer for maximum back,
ground noise.
4 .. Set Selectivity Switch for the required oper'
ating conditions -See Selectivity Curves-
Figure 12.
5'. Set Noise Limiter-A VC Switch for the re'
quired operating conditions.
6. Set R,F Gain Control fully clockwise.
7. Set Audio Gain Control about halfway
8. Tune in the station.
9. Reset Audio Gain Control to give deslred
volume.
10. Reset Selectivity and Sensitivity (R,F Gain)
Controls and Noise Limiter Control
in aC'
cordance with requirements due to inter'
ference, station transmission, and other 'con,
ditions.
11. Set Tone Control for preferred tone.
12. On CW operation set Power·Transmit,Re'
ceive Switch to "Rec. CW" (position 4) and
set BFO Control to give desired pitch.
13. If the receiver is subject to vibration, the tun-
ing may be locked by turning clockwise the
knurled screw directly beneath the tuning
knob.
Turning the screw moderately tight
will lock the tuning.
Diversity Reception -Connect together the ter-
minals marked "diversity," Pigure 3, on two or three
of these receivers, and equip each receiver.with a
separate antenna.
The "diversity" terminal is con"
nected inside the receiver to the A VC circuits. Tune
as explained.
VIII
MAINTENANCE
This receiver should maintain its correct factory ad,
justments over a reasonably long period of time.
Causes of trouble and the probable sequence of their
development are outlined in the following paragraphs:
1. Vacuum Tubes - A noticeable decrease in the
sensitivity of the receiver
us~ally indicat~ worn
out vacuum tubes.
If the sensitivity is low. re'
move and check the tubes' in a reliable tube
tester or substitute new tubes one at a time.
See Technical Summary, and Schematic Dia'
gram Figure 11. Tube socket voltages are given
in Table 2.
2.
Range Switch - A switch may operate defec-
tively on certain positions after long periods of
inoperation. Usually rotating the switch back
and forth several times will clean
the contacts
and operation will become normal.
A bad range'switch contact is likely
to cause a
change in the sensitivity of the receiver, or the
frequency of a received signal, as
the switch is
moved back and forth slightly in a certain fre,
quency band position. A further check
is to
turn the switch off and on at one particular fre'
quency band several times apd note the ap'
parent sensitivity of the receiver each time the
switch comes into position.
The sensitivity
should be the same each time and may be ade'
quately judged for this test by listening to the
receiver background noise.
3. Automatic Volume Control and Tuning Meter
-The A ve voltage is obtained from the second
10
detector. It controls the first and second R,P
and nrst and second I·P tubes. The tuning meter
is connected in the cathode circuit of the 1st I'P
tube and thus records changes in cathode cur'
rent caused by changes of AVe voltage applied
to the grid. The tuning meter should normally
give a low scale reading when
no signal is being
received.
To adjust this meter;fune the receiver
to a point free
of signals, turn the sensitivity
control
to maximum, switch in AVe, switch
crystal
"Out," have antenna trimmer turned
off resonance, and then adjust the potentiometer
R21 Jlt the back of the receiver, as shown in
Pigure 3, until the meter pointer just coincides
with the mark at the low end of the scale. The
meter will ustlally rise slightly when the antenna
trimmer is tuned to resonance.
4. Circuit Alignment
Alignment Tools-,Special tools for align'
ment of R,P and I·P circuits are provided. They
ate mounted in fuse clips on either side of the
gang condenser cover, and are available after
removing the large R,P unit cover.
The shorter
one of the
two is for adjustment of all R·P and
I·P coils, and the longer one is for adjustment
of the plunger type trimmers.
One end of this
tool
is for turning the lock nut on the trimmers
and the
oth~r end has a hook for engaging in
the hole in
the end of the plungers. After ad-
justment, the lock nut should be securely tight-
ened.

.i . i i n i 08 ' i, /Ji.~~~5:t~H)
L42 -:r - - - -- _ 11 _ 7 I C21-"'sBANO
(L41 BOTTOM) \ ~-.......... /~ 22,'TDOKC
L4l -::1---- -1101 "3
ItO
LF. CI9-*zlWlo L5l-.28AM~54-""8AHD //;; -[LSS-"SBANO
(L44BOTTOM)\ [~-r;'F.) 6SS1 .. '4' .~KC d/1570KC/ 11,
90
°5/:'/ 2'lOOOKC
L4S -::J" TR"~ R"NS B.£OTRAKS \. l.!J ~ ~ Gr t!f/®--- rr CI6 -., BANO
(LA' BOTTOM)I __ ~6.F.O. 6J5 6SS1 CU®~'C'ZS"'''BANO / 11 1600KC
LZ2. -r Si
TRANS
~=o 6J5 16))00 KC At ~ -~ LSt- *1 BANC
(0'" TOP) H6 lID 2110 ~y . QJ ~ 535 KC
L3b 6 i~~~J{?·F.tF~~n 1ST~' 51"'38AHO $---- - - C32-*S8,ANO
CL3S6OTTDMlr----- A"'S, S 0"" 6SA1 .450 KC __ IT 3'Z,000KC
. ~ISE" '" . <;... - - "li-
H!---..) 6H6 LIMITED ...... ?C6O''zBANO_ ~C&+*4eA"O t§)-r ~_ .JI C6S-
Me
BAND
\_ ............ 1"'" _1),...00 <4)QO -..... Ci1"' (6,400 KC ~ ~. -l31'!l
OO
KC
L'33 1_ - P;-1:;~6SG1 .;:~~ ~ Ug.. •• "W.DI~ ...... '®o... L'31-~BAND
(l,!2!BOTTOM)i' ~ _~ RA /' C!iI: 17.,100KC ~~" '22,5DOI'\C
L'54 -J
1
_\6SJ 1J1U ~F. f!l1.2516- ~"; 6SG1 \ LZ'LZ ..... ,.Alto ..... ,', '~I 'C59-·1 BAND
(OM TOP) ~_ ia'BANo" @ 4600KC ~ @l~, " I 1500 KC
-- 1700 KC _'~ ~,-, '\ ,
PHASING Tl. UTPUT LOAD ~SI ~ {li;1 C6Z""'BAN r<iiil '\ Cii!. "$ LZ~L24-.,BANO
CONTROL UTPUT 6K6 ~_J!!!'l/ ~"'l{ 1t,500KC ..... , tiill' \~ ,60 KC
C3S..................... °TRAHS GT (0~11 'i> C41-"48ANO IJ \ ..,. '\ \, LlO-"'s BAN D
tlt18AND_ __/.::::-i:so \ I 6SG1 r 18
/
400 KC
j I \ \ \
~\1S'400 KC
4300I<C l~"""'-'::"'::[FILTER / I L11,U8- I \ \\ C66-*SBAND
L1t CHOK",J 1
ST
R.F., *381\NO I " \ \\" \'22,'500KC
-4 BAND ., ...... ... 4tOOl'lc. \ ~
lt1DOKClI--------..... -- _.-"~BANO I I \ \ C37-'" 1 BAND
,----- '1500KC I \1 !lOO KC
IS
'6
- Tt J I \
~ t.ND POWER 1 \ ~ L'Zl-*'SBANO
1
700KC TRAMS. ~ , 22,500KC
- I I " ,
U3-L14--1BAND C45-¥s9AND
\ SOOKC 3\,SOOKC
\C43-"BAND L'20-*'$BANO
2'1 0 ....c '8,400 Kc:.
1\-88'9
Figure S-Diagram of Top of Cluusis
t.FAlignment - The intermediate frequency is 4H
e:The most satisfactory method of I·P alignment is by means of a sweep oscillator and cathode ray oscillo;
graph. Pollow the sequence as given below.
Oaci1Iograph Connections ..•....................•...• Vertical "HI" to Terminal C on last I·P Transformer
(L47, L48), Vertical
"LO" to chassis
Dummy Antenna ................................... : ..•. Insert in series with generator output. 0.01 mfd.
Connection of Generator Output Lead ............••.......•....•.................... " See chart below
Connection of Generator Ground Lead ......•.•....•••............•........................ To chassis
Position of Power·Transmit·Receive Switch ..........•........................... Position 3 (Rec. Mod.)
PO$i.Uon of R·P Gain Control. . . . . . . . . . . . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Pully clockwise
l1'oeition of Selectivity Switch .........•............• ' ....................................... Position 2
Position of Noise Limiter and A VC Switch .......... '" ........................... " Position 4 (AVe)
LOCATION OF PARTS AND AUGNMENT ADJUSTMENTS ON CHASSIS
Step'
1 Generator Connections
6SG7-lrd I·P Grid
6SG7 -2nd I,P Grid
Trimmer Adjustments (See Pig.
S')
L47, L48 Trimmer Punction
4th I·P Transformer
3rd I·P Transformer
2nd I,P Transformer
2
1
4 6SG7 1st I·P Grid MA7 -1st Det. Grid
L41,
U2, U3, L44
US', L36,
U7. U8
L32, L33
1st I,P Transformer
Before performing step 4 abo've. set crystal phasi,ng
control C7S' at approximately one fifth of its maxi·
mum capacity. This is approximately its final setting
and changing it appreciably will slightly detune the
first I-P transformer.
With Selectivity Switch in Position 2 the I·P band
width is normal without over,coupling in the trans'
formers.
With Selectivity Switch in Position I, the
second and third I·P Transformers are expanded and n
over-coupled. It is well in going through the alignment
steps outlined above to check the I,P curves on the
oscillograph screen with switch in Position 1 to see
that the curves expand symmetrically.
Adjustment of Crystal Phasing
Control- This ad-
justment is best made by means of a signal generator
and a high resistance sensitive DC voltmeter such as
the RCA Junior Voltohmyst. Place Selectivity Switch
in Position 3. Connect the generator to the grid of the

6SA7 first det., and the Voltmeter to Terminal C on
last I,F transformer (L47, L48). Tune the generator
to about 7 k.c. off I,F resonance and adjust the crystal
phasing control
C7S for minimum response.
Adjustment
of Crystal Load Circuit -Make con'
nections as for the preceding adjustment.
(a) Place Selectivity switch in Position
3. Rock the
signal generator frequency back and forth
across the I,F resonant frequency and adjust
the crystal load circuit trimmer L3'1 for sym'
metrical round,top curve.
(b) Place the Selectivity switch in Position 4. Rock
the signal generator frequency and adjust trim-
mer C81 for symmetrical curve.
(c) Place the Selectivity switch in Position
5. Ad,
just trimmer C80 rocking the signal generator
as for (a) and
(b) above.
The above three adjustments are very critical and
must be made carefully to obtain symmetrical curves.
Adjustment
of Wave Trap - A wave trap is con-
nected across the broadcast band antenna primary to
increase the rejection of I·P signal frequencies. With
the range switch on Position I, apply a modulated I·F
signal to the antenna and ground terminals. Adjust
the wave trap trimmer
U7 (See Fig. 3) for minimum
output.
The wave trap should be adjusted before the
final R- F alignment on No. 1 band, or the antenna
coil alignment may be affected.
R·F Alignment - A signal generator covering a
range from
53 5 k.c. to 32 megacycles, and an output
voltmeter, are required. It is desirable to connect a
speaker across the output terminals.
The output volt-
meter should then be connected across the speaker
voice coil. The output impedance is 2.25 ohms. Re·
move the cover from over the R·F unit by loosening
the four knurled screws and lifting
off.
Output Meter Connections ...................................... , ............ Across speaker voice coil
Dummy Antenna
................................................................... See chart below
Generator Modulation. . . . . . . . . . . . . . . . . . . . . . . . . •. . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 30% at 400 cycles
Position
of Tone Control. ........................ " . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Fully clockwise
Position
of Antenna Trimmer. . . . . . . . . . . . . . . . . . •. • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. See chart below
Position
of Power-Transmit-Receive Switch ..........•...........................• Position 3 (Rec. Mod.)
Position
of Range Switch.. . . . . . . . . . . . . . . . . . . . . . . •. • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. See chart below
Position
of R·P Gain Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Fully clockwise.
Position
of Audio Gain Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Fully clockwise
Position
of Noise Limiter and AVC Switch .......................... < ................ Position 4 (A VC)
Position of Selectivity Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . •. . . •. . . . .. Position 2
LOCATION OF PARTS AND ALIGNMENT ADJUSTMENTS ON CHASSIS
Oper- Range
anon Switch
No. Position Position of Dial Generator Frequency Dummy Antenna
1 Extreme low end 53 5 200 mmf
2 Extreme high end 1,600 200 mmf
Position
of Antenna
Trimmer
3 Repeat 1 and 2 until extreme end frequencies are as indicated.
4 1 1,500 k.c. 1,500, 200 mmf \ Max.
output
5 I 600 k.c. 600 200 mmf Untouched
6 Repeat 4 and 5 until circuits remain in alignment over the band.
7 2 Extreme low end 1,570. 200 ohms
8 2 Extreme high end 4,550 200
ohms.
9 Repeat 7 and- 8 until extreme end frequencies are as indicated.
10 2 4,300 k.c. 4,300 200 ohms Max. output
11 2 1,700 k.c. 1,700 200 ohms UIA:ouched
Trimmer Adjustments for
Max. Peak
Output
(See Figures 3 and S)
L51
C16
C37.C59
L2. Ll4, L24
152
C19
C38,C60
L4, Ll6, L26
12 Repeat 10 and 11 until circuits remain in alignment over the band.
13 3 Extreme low end 4,450 . 200 ohms L53
14 3 Extreme high end 12,150 200 ohms C22
15 Repeat 13 and 14 until extreme end frequencies are as indicated.
16 3 11,500 k.c. 11,500 200 ohms Max. output C39, C62
17 3 4,600 k.c. 4,600 200 ohms Untouched L6, Ll8, L28
18 Repeat 16 and 17 until circuits remain in align ment over the band.
*19 4 Extreme low end 11,900 200 ohms
L54
20 4 Extreme high end 16,600 200 ohms CH
21 Repeat 19 and 20 until extreme end frequencies are as indicated.
22 4 16,400 k.c. 16,400 200 ohms Max. output C41, C64
23 4 12,100 k.c. 12,100 200 ohms Untouched L8, L19, L29
12
Trimmer
Function
Low end osc.
High
end osc.
lst& 2ndR,P
Ant. & Ist·
and 2ndR-P
Low end osc.
High end ~sc.
1st &2nd R-P
Ant. & 1st
and 2nd R-P
Low endosc.
High end osc.
1st & 2nd R-P
Ant. & 1st
and 2nd R-P
Low end osc.
High end osc.
Ist&2nd R-P
Ant. & 1st
and
2nd R·F

Oper-
ation
No
Range
Switch
Position Position
of Dial Generator
Frequency Dummy
Antenna
Position
of Antenna
Trimmer
Trimming Adjustments for
Max. Peak
Output
(See Figures 3 and 5)
Trimmer
Function
24 Repeat 22 and 23 until circuits remain in alignment over the band.
*2 j 5 Extreme low end 16,100 200 ohms LH Low end osc.
High end ~sc.
26 5 Extreme high end 22,700 200 ohms C27
27 Repeat
25 and 26 until extreme end frequencies are as indicated.
28
5' 22.500 k.c. 22,500 200 ohms Max. 'output C43, C66 1st & 2nd
R,P
Ant. & 1st
and 2nd R-P
29 5' 16,400 k.c. 16,400 200 ohms. . Untouched LW, L20, 130
30 Repeat 28 and 29 until circuits remain in alignment over the band.
*31 6 Extreme low end 22,000 200 ohms 156
Low end osc.
High end osc.
32 6 Extreme high end 32,OQO 200 ohms C32
33 Repeat 31 and 32 until extreme end frequencies are as indicated.
34 6 31,500 k.c. 31,500 200 ohms Max. output C45, C68
lst&2nd R-P
Ant. &> lst
and 2nd R,P
35 6 22,500 k.c. 22,500 200 ohms Untouched Ll2, L21, L31
36 Repeat 34 and 35 until circuits remain in alignment over the band.
On ull bnud .. tlte oscillator tr""ks ,IUO\'e the slgual frequency.
It mOTe Iblln one Pellk 18 ohtnlll"ble on ollclUator, use tbe b!gbf'r frPlluellcy petlk.
• NOTE: On all coils, except Nos. 4, 5, and 6 band oscillator coils (LS4, LS5, and L56) turning the Core clockwise in,
creases the inductance. On the above three mentioned coils, turning the core clockwise decreases the inductance.
Adjustment of Beat Frequency OscUlator -Tune
in a signal either R-P or I,F to exact resonance with
li'd'wer-Transmit,Receive Switch at ·'Rec. Mod" (Fig.
• )+ Turn on beat frequency oscillator by turning
switch to "Rec. CW." If zero beat does not fall within
the range of the BFO control. adjust BFO Trimmer
L22 (see Pig. 5) until zero beat occurs at the mid-point
setting of the BFO control.
IX
MECHANICAL CONSTRUCTION
The receiver has been designed to be very rugged
so· that it will stand up under severe conditions of
&.se; and yet have all parts available for easy replace'
ment, All component parts such as transformers,
~okes, ,~ter and by'pass capacitors, etc., are mounted
with sctews and nuts rather than with rivets. All wir'
Ftg.othe.r: than that involving high frequency circuits
"-:inade up in the form of a laced cable so that no
~e leads are left floating which might tause damage
9:t'change capacity to various portions of the circuit.
The tuning condenser is mounted so as to be rigid
Wi~ respect to the tuning unit,·and yet is flexible with
tespect to the chassis. This prevents distortion of the
chassis from having any appreciable effect on the
atabilityof the oscillator.
The R·F unit which consists of the tuning con'
denser. tuning unit, range switch, and all
of the R,F
~d Oscillator coils and trimmers, is mounted on a
aeparate base-which bolts to the main base. The vari,
OUS coils and trimmers on this base may be easily
replaced by means of a single nut which screws on
the iI1dividual mounting bushings. However if a
major
p~pair is to be made such as replacement of the
range ·switch. it is necessary first to remove the com-
plete R-F unit from the receiver. To do this the follow'
ing procedure should be observed:
1. Remove the chassis and panel from the cab-
inet by removing the four panel mounting
13
screws and sliding the chassis forward out of
the. cabinet.
2. Remove the knobs by means of the small
wrench held in
the spring clip. on the right
hand side of the chassis. This wrench fits
the
set screws in all knobs except the main tuning
knob. For this knob use an ordinary small
screw driver.
3. Remove the panel by removing the eight nuts
with which
it is held to the support brackets.
4. Remove the large cover from the top of the
R,F unit, by removing the four knurled nuts
with which
it is supported.
5. Remove the small cover fro'm the tuning con·
denser, by removing the eight knurled nuts
with which it is supported.
6. Remove the dial light sockets where they a.re
dipped on to the tuning unit.
7. Remove the antenna trimmer shaft extension
by loosening set screw in coupling with same
wrench as used above for knobs.
8. Remove support bracket from flvwheel
tun'
ing shaft. ,
9. Remove main dIal, vernier dial, and flywheel
by loosening set screws with same wrench as
used fJr knobs.

10. Disconnect the eight leads which connect the
TABLE i-TUBE SOCKET VOLTAGES
R,P unIt to the main base. These leads are Screen Cathode
as follows:
Tube
Volt. Volt.
(a) Two on the antenna terminal board
(blue and black). RCA-6SG7
(b)
One on number 7 pin of the 6K6GT 1st R·P Amplifier
..
235'
l5'0
0)
output tube (brown). RCA-6SG7
(c) One
on terminal E of the crystal load 2nd
R~ P Amplifier 2
235'
15'0
0
circuit (yellow).
RCA-6];
(d) One on terminal E
of
the
first· I,P Oscillator
........
3 110
0
RCA-6SA7
Transformer (red).
1st Detector ......
4
235' 50
2
(e)
One on terminal P
of
the first I·P RCA-6SG7
Transformer (blue). 1st I,P Amplifier
..
;
235' 150
.7
(f)
One on pin 6 of the second I·P tube RCA·6SG7
(green). 2nd I·P Amplifier. 6 235
15"0 . 1.3
(g) One on pin 7 of the second I·P tube RCA·6SG7
(brown). 3rd I·P Amplifier. 7
235 l5'0 3.1
In addition, the by'pass condenser which
RCA·6H6
grounds to the R·P unit near the second I·P 2nd Det. &
AVC.
8
tube must be disconnected. RCA-6H6
Noise Limiter .....
9
11.
Remove eleven screws which hold R,P unit
RCA6SJ7
to main base. Three of these are on under side
1st Audio Amplifie 10
83
34
0
of chassis along the front edge. The other
RCA,6K6GT
eight are removed from the top. Power
Output ....
11 256
240
0
12.
The R·P unit may now be removed from the RCA,6j5
bottom by lifting up first the rear of the R,P B.F.O.
............. ;0 l2 40
0
unit and sliding it back out of the opening.
RCA-VR'I;O
After the unit has been repaired it may be re'
Voltage Regulator. 13 15'0
0
assembled by following the above procedure RCA-5'Y3GT
in reverse order. Rectifier •
......... ~ ~ « 14 300
X
PARTS LIST
Symbol
Designations
Cl, 11, 33, 47,
51, 52, 64, 63,
74,83,117,
118,121,122
C2
CS, 6, 35, 40,
49,60,70,77
C4.5, 13, 14,
34,57
C7
C8
C9,10
C12
Cl&. 21
C16,19,22,
87,59
C17
C18
COO
C23,28
C2~
C25, 27, 32,
41, 43, 45, 64,
66,68
C2I6, 29, 42,
65. 67, 69
C30
CSl
C36,58
C38, 39, 60,
62, SO,81
DESCRIPTION
CAPACITORS
Capacitor, 4,700 mmfd. ..
Capacitor, antenna trim-
mer .............. : .. .
Capacitor, variable,
as-
sembly, 8 sections .... .
Capacitor,
220 mmfd ... .
Capacitor, 18
mmfd ..... .
Capacitor, SS
mmfd ..... .
Capacitor,
22 mmfd ..... .
Capacitor, 66
mmfd ..... .
Capacitor, 15
mmfd ..... .
Capacitor,
air trimmer ..
Capacitor, 525 mmfd. ... .
Capacitor,
13 mmfd. .... .
Capacitor, 1,550 mmfd.
..
Capacitor. 3,000 mmfd .. .
Capacitor, 2,700
mmfd .. .
Capacitor,
air trimmer .. .
Capacitor, 82
mmfd .....
Capacitor, 3,900 mmfd. ..
Capacitor, 82 mmfd. ... .
Capacitor, 180 mmfd.
... .
Capacitor, air
trimmer .. .
RCADrawing
and Part No.
M-80079-531
M-2531S0-2
P-92444-501
K-90581-S41
K-9058l-315
K-90581-321
K-90581-317
K·90581-9ZI
K-90681-213
M-95534-503
M-86079-508
K-90581-212
M-86079-533
P-721l33-9
P-721133-8
M-95534-501
K-90575-2'81
P-720638-4.6
K-90574-2S1
K-90581-239
M-95534-502
Symbol
Designations
C44, 46
C48,
lOO, 110,
103,106,107
C53
C53,76,93
C61,120
C71, 95, 102,
79,84,92
C76
CB6
C96, 97, 98
C99, 112, 113
CIOS
CllI, 116, 119
J1
*J2
Lt, 2
L3,4
L5,6
L7,8
L9,10
• n"" .. t .... ·rs with ~ ..ri:ll Xos. b.. low OO:lOOO use Phone Jack-nwI!'. K·98!l65.2.
14
DESCRIPTION
Capacitor. 91 mmfd •.....
Capacitor, by-pass, as-
sembly, S sections, 0.05
mfd. each ............ .
Capacitor, 6.8
mmfd ..... .
Capacitor,
by-pass, as-
sembly, S sections, 0.01
mfd. each ........... .
Capacitor,
15 mmfd ..... .
Capacitor, by-pass,
as-
sembly, 8 sections, 0.1
mId. each ............ .
Capacitor,
crystal phas-
ing trimmer ......... .
Capacitor,
BFO Trimmer
Capacitor, filter pack, as-
sembly, S sections, 4
mId. each ........... ..
Capacitor, by-pass, as-
sembly, 3 sections, 0.25
mfd. each ............ .
Capacitor,
560 mmfd •....
Capacitor, 2,700 mmfd. ...
CONNECTORS
Socket ................ .
Phone Jack ............ ..
INDUCTORS
Antenna Coil, No. 1 band
Antenna Coil, No. 2 band
Antenna Coil, No. 8 band
Antenna Coil. No. 4 band
Antenna Coil, No. I) band
RCADrawing
and PartNo.
K-90675-2SS
K-9S()M-l
K-90581-306
K-980.U-4
K-90581-3lS
K-980S4-2
M-2531S2-3
M-263132-l
P-70028-515
M-421395-509
K-98965-1
M-~
M-95521-50l:
M-95521-502
M-95521-503
M-95521~

Symbol
Designations
Lll,12
LIS, 14, 23.
24
L15,16,25,
26
L17,18, <J:I,
28
L19,29
L20,SO
L21,31
L49.5O
L51
L52
L53
L54
L55
L56
L67
Nl
R1.6,19,49
R2, 33, 36, 47
'Rs, 10, 12,16.
22,.26,31,34
R4,9,14
RIi
R7.17
RS,18
Rl1
R1S
R20,39
R23, fD. 50
R25
Rso
R32
R35
R37
Rsa
RfO
Ril
R42, 63
R43
R44
R45
R46
R48
R51
PARTS LIST (Continued)
DESCRIPTION
RCADrawing
and Part No.
Antenna Coil, No. 6 band M-95519-507
R.F. Coil, No. 1 band... M-9552D-50l
RF. Coil, No. 2 band .. .
R.F. Coil, No. 3 band .. .
RF. Coil, No. 4 band .. .
R.F. Coil, No. 5 band .. .
R.F. Coil, No. 6 band .. .
Coil.
Filter Choke ...... .
Oscillator Coil, No. 1
band ................ .
Oscillator Coil. No. 2
band ............... ..
Oscillator Coil,. No. 3
band ................ .
Oscillator Coil, No. 4
band ................ .
Oscillator Coil, No. 5
band ................ .
Oscillator Coil, No. 6
band ............... ..
Wave trap, 455 k.c ...... .
METER
TWling Meter .......... .
RESISTORS
Resistor, 33,000 ohms. Yz
watt ................ .
Resistor, 2.2
meg, ~ watt
Resistor, 1,000 ohms, ~
watt ............... .
Resistor, 100,000 ohms,
Yz watt ............. .
Resistor, 1 meg, ~ watt
Resistor, 10 ohms, ~ watt
Resistor, 5,600 ohms, ~
watt ................ .
Resistor, 10,000 ohms, ~
watt ................ .
Resistor, 560
ohms, ~
watt ................ .
Resistor, 100
ohms, ~
watt ................ .
Resistor, Meter Adj. Con-
trol ................. .
Resistor, 560,000
ohms, ~
watt .. ~ ............. .
Resistor, 180
ohms, ~
watt .. , ............. .
Resistor, 2,700
ohms, 4
watts ............... .
Resistor, 390
ohms, ~
watt ..........•......
Resistor, 680,000 ohms, ~
watt ................ ,
Resistor, 1 meg, ~ watt
Resistor, 1.5 meg, ~ watt
Resistor, 270,000 ohms, ~
watt ................ .
Resistor, 100,000
ohms, ~
watt ................ .
Resistor, 390,000
ohms, ~
watt ................ .
Resistor, 100
ohms, 4
watts ............... .
Resistor, 160
ohms, 4
watts ............... .
Resistor,
l5.ohms, ~ watt
Resistor, R.F. Gain Con-
trol ................. .
Resistor, Noise Limiter
Control ............. .
Resistor, Audio Gain
Control .",.".,.""
M-95520-503
M-9552iO-OO4
M-95519-501
M-95519-502
M-95519-600
K-9014S3-501
M-95520-505
M-95520-506
M -95520-607
M-95519-504
M-95519-505
M-95519-506
M-76299-505
K-98949-1
K-86098l-80
K-860981-33
K-82283-62
K-82283-86
K-82283-31
K-867970-338
K-82283-71
K-82283-74
K-850981-59
K-82283-50
K-1151402-4
K-82283-95
K-82283-63
K-90497-3
K-85098l-57
K-850981-96
K-85098l-3l
K-850081-l00
K-85098l-91
K-86098l-86
K-82283-93
K-00497-l
~K-90497-2
K-867970-340
K-251402-2
K-25l400-2
K-251402-3
Symbol
Designations
R52
R54
R5.5
tR56
SI to 16
S17 to 2(}
S21,22
S£3,24
S25
Tl
:f;T2
T3
T4
T5,6
T7,8
T9
T10
TBl
TB2
:f;TB3
Xl, 2, 3, 7;
8,11
X4,12
X5,6,10,
13,14
X9
Receivers with Serial Nos. below 003000 use R56 Resistor K-90497 -4 (5 ohms).
DESCRIPTION
Resistor, Tone Control ..
Resistor, 2,700 ohms. ~
watt ................ .
Resistor, 6,800 ohms, ~
watt ................ .
Resistor, 1,000 ohms, 4
watts ............... .
SWITCHES
Range Switch ......... .
Selectivity
Switch ...... .
A.V.C.-N.L. Switch ... .
Off-Trans.-Rec. Switch ..
Voltage Tap Switch .....
TRANSFORMERS
Transformer, Power,
Universal ........... .
Transformer, Output ... .
Transformer, 1st I.F .... .
Transformer, Cry s t a I
Load I.F ............. .
Transformer, 2nd I.F ... .
Transformer, 3rd I.F ... .
Transformer, 4th I.F ... .
Transformer, BFO ..... .
TERMINAL
BOARDS
Terminal Board, Antenna
and GroWld .......... .
Terminal Board, Output
Terminal Board, Output
TUBE SOCKETS
Tube Socket .......... .
RCADrawing
and Part No.
K-1151402-1
K-8509S1-67
K-850081-72
K-90497-5
M-2I53097-1
M-1153134-l
M-263099-1
M-263098-1
K-99565-1
K-901432-501
K-90l573-501
P-92430-501
P-92430-506
P-92430-503
P ..92430-500
P-92430-502
P-92430-504,
M-86927-18
M-86927-17
M-86927-19
M-421395-507
1rube
Socket",., ."". M-!2l~lO
Tube Socket., ... ,."., M-42l3e5-509
Tube Socket ......... ..
CRYSTAL
Crystal (455 KC) ....... .
MISCELLANEOUS
Resistor Board .......•..
Tu,ning Unit ........... .
Dial Window ........... .
TWling Dial Assembly .. .
Vernier Dial Assembly ..
Flywheel Bracket As-
sembly .............. .
Flexible Coupling ...... .
Battery Plug Assembly ..
Pilot Lamp Socket As-
sembly .............. .
Pilot Lamp Socket As-
sembly .............. .
Pilot Lamp ........... ..
Lock Screw .... , ....... .
Wrench (Knob & Coup-
ling Set Screw) ...... .
Knob (Large) ... , ...... .
Knob (Medium) ........ .
Knob (Small) ......... ..
Set Screw (Large Knob)
Set Screw (M e diu m
Knob) ........ , .. " ..
Set Screw (Small Knob)
Power Cord ... , ........ "
LF. Transformer Adj.
Tool ..... , .......... .
Air Trimmer Adj. Tool ..
Coupling (Ant. Trimmer
Shaft) .............. .
Ant. Trimmer Shaft., .. .
M-421395-508
K-869226-501
K-98958-1
P-924l.7-1
29932-2
K-9894.7-501
K-98947-002:
K-99819-501
K-9895O-1
K-99895-501
K-98988-502
K-9698~1
K-61114-15
K-99821-1
K-828505-12
P-712336-503
P-712836-505
P-712336-507
K-59101-6
K-843365-13
K-843365-12
K-99883-1
M-86183-50l
M-81059-501
K-99630-1
K-99631·l
R~h'ers with Serial Nos. belOW 003000 use T2 Output TransfOrmer K-901430-501 and do not ha\'e Output Terminal Board TB3,
15

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