February 1932 RadioCraft
[Table
of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from RadioCraft,
published 1929  1953. All copyrights are hereby acknowledged.

Once again I have given selflessly and freely of my time and talent to make available resources to those
seeking certain knowledge regarding vintage radio circuits ;) This time it is the Radio Service Data Sheet
for the Howard Model 45 A. V. C. Superheterodyne with Model A. V. H. Chassis. The info was published in a 1932
edition of RadioCraft magazine, one of Hugo Gernsback's many endeavors. Also on the page is a
complete list of all such schematics and tuning and repair data posted thus far.
Howard Model 45 A. V. C. Superheterodyne with Model A. V. H. Chassis
Radio Service Data Sheet
The values of the components of this
receiver chassis are as
follows: Resistors R1 , R3, R5, 1/5meg. (1/3watt); R2, R6, 500
ohms (1/5watt); R4, 6,000 ohms (1/2watt); R7, 30,000 ohms; R8,
volume control, 1/2meg.; R9, 1/2meg.; R10, 3,000 ohms; R11, 2,000
ohms; R12, R13, 150,000 ohms (1/2watt); R14, 2 megs.; R15 R16R17R18R19,
voltage divider, 9,900 ohms; R20, R21, 10 ohms (centertapped);
R22, 200 ohms.
Condensers C4, C5, C6, C7, I.F. trimmers; C8, C9, C10, C15, C16,
0.1·mf.; C11, 0.00025mf.; C12, 0.001mf.; C17, C18, 0.25mf.; C19,
C23, 0.5mf.; C21, 0.05mf.; C24, 1.0 mf.; C25, C26, 8 mf. (420
volts); C27, 4 mf. (420 volts).
In the interest of obtaining best results with the Automatic
Volume Control receiver, it is important that the type '27 control
tube V9 be a selected one, with a definite plate current cutoff
when tested at 180 volts plate and 20 volts bias on the grid. This
cutoff should be less than 5 microamperes. If there is no means
available for checking the tube (in the form of a special tube tester),
an immediate check for tube performance can be obtained in the set
itself.
For instance, disconnect the antenna and shortcircuit the aerial
lead, leaving the control tube out of the socket, and note the swing
of the tuning meter. Then insert the tube in the socket and if it
is a good automatic volume control tube, there should be no change
in the position of the pointer on the tuning meter. If there is
a change in the position of the tuning meter pointer, namely, a
swing toward the right, it is an indication that the A. V. C. tube
does not have a definite plate cutoff; instead, it is drawing plate
current and as a result the bias voltage on the regular R.F. and
I.F. tubes has been raised, with the consequent cutting down in
plate current.
The Model 45 speaker has a 350ohm field, and as such it cannot
be used with the Models 35 and 40 receivers.
The receiver housed in the regular cabinet is the "Model 45";
the chassis is the "Model AVH."
The automatic volume control functions in holding the seconddetector
input voltage at a definite level, a system which is different from
that in other receivers. A reduction of background noises, between
stations, will be noted.
The only service met with to date on the Model "H" receiver has
been in connection with the shorting out of the R.F. plate bypass
condenser, the red lead of which may accidentally become wedged
underneath the first I.F. coil can. The insulation does not cut
through immediately but, after being in service for a number of
days, the pressure on the insulation may be such as to gradually
cut through it, shorting out the plate bypass condenser, and thus
producing zero voltage on the plates of the R.F., first detector,
and I.F. tubes.
The A. V. C. tube is so connected by means of a 2megohm resistor,
R14, that the grid is at absolute "B" potential. The cathode of
the tube is connected to a point on the voltage divider which is
at 24 volts positive, with respect to "B" or the grid. There then
exists between the cathode and the grid a potential difference of
24 volts with the grid negative by this amount. The plate of this
tube connects to ground by means of two 150,000ohm resistors, R12R13.
Since ground is connected to 124 volts, positive (with respect to
"B"), there exists between the cathode and the plate a potential
difference of 100 volts. In order to bypass any R. F. energy which
may appear on the plate, a noninductive condenser C22 is connected
from the plate of the A. V. C. tube to the cathode.
With the condition of nosignal there exists a bias of 24 volts
and a plate potential of 100 volts. Under these conditions, there
is no plate current flowing and the tube is said to be adjusted
to cutoff. Since no plate current is flowing, there exists no voltage
drop across the plate circuit resistors and, therefore, there is
no bias voltage on the grids of the controlled tubes. The only bias
on the R.F., first detector, and I.F. is caused by the respective
voltage drops across their cathode resistors. These resistors are
designed to give the most sensitive operating point.
In the case of a received signal, energy passes through the receiver
to the seconddetector grid. Here the A. V. C. (automatic volume
control) tube grid, and the seconddetector grid, are in parallel.
The signal voltage is fed to the grid of the A. V. C. tube through
a small fixed condenser, C11.
It will be seen that during the positive half of the incoming
cycle, the peak voltage of the signal swing subtracts from the original
bias voltage; which means that the instantaneous bias on the tube
is less than the original bias and the tube begins to draw current
in its plate circuit. Since this current flows in the resistors
in the plate circuit of the A. V. C. tube, there exists a voltage
drop across these resistors; also, the flow of the electrons is
from plate to ground so that the plate becomes negative with respect
to ground. Now, since the original potential of the cathode of the
R.F., firstdetector, and I.F. tubes is positive with respect to
ground, it follows that if the grids of the respective tubes are
connected to a resistor in the plate circuit of the A. V. C. tube,
that any potential existing across this resistor is added to the
original bias and makes the grids more negative than the original
bias by the amount of the voltage drop across the resistor in the
A. V. C. tube plate.
It is at once apparent that the greater the signal voltage appearing
at the grid of the A. V. C. tube, the more plate current will flow
in the plate circuit: an increase in plate current means an increase
in bias on the R.F., firstdetector, and I.F. tubes; an increased
bias on these tubes means less amplification and, therefore, less
grid swing on the seconddetector and A. V. C. tube. This cycle
goes on until a constant voltage is obtained across the seconddetector
input, or, in other words, until a condition of equilibrium is reached.
Since R8 is located where the tone control is normally connected,
it was necessary to relocate the tone control, C13R9C14. As less
resistance is included between the two condensers, they become more
effective in bypassing the higher audio frequencies; at the same
time, they resonate the primary of T2 to a lower audio frequency.
Posted February 25, 2015
Radio Service Data Sheets
These schematics, tuning instructions, and other data are reproduced from my
collection of vintage radio and electronics magazines. As back in the era, similar
schematic and service info was available for purchase from sources such as
SAMS Photofacts, but these printings
were a nocost bonus for readers. There are 227 Radio Service Data Sheets as of
December 28, 2020.

GE
Model 250 Radio Service Data Sheet
 Hoffman
Model A300
 Emerson
Model 505
 Olympic
Models 6501, 6502, 6503
 Radiola
Models 615, 6110
 Farnsworth
Models ET060, ET061, ET063
 General
Electric Model 321

Garod Model 6AU1
 Truetone
Model D4620
 Westinghouse
Model H148
 Wards Models
54BR1501A, 1502A
 Majestic
Models 8S452, 8S473
 RCA Models
Q22A, Q32
 Zenith Model
5G003ZZ
 Mantola Models
92503 and 92504
 Emerson Model
508 Series 87434351 and Up
 Belmont Model
A5D118
 Wards Model
74BR2707A
 Crosley Model
56TPL
 Admiral Model
7C60 Chassis 6B1
 336
Belmont Radio Model 6D111, Series A

333 General Electric Models 100, 101, 103 and 105
 RCA Victor
Models 54B1, 54BN, 54B2, 54B3 Radio Data Sheet 335

National Union "Presentation" Radio Model G619

Zenith Radio Models 8H032, 8H033, 8H050, 8H052, 8H061

General Electric Farm Radio Model 280

Admiral Model 6RT447B1

Montgomery Ward Airline Model 04BR1105A Radio
 Belmont
Model 678 AutoRadio Set
 Sentinel
Model 217P Portable Radio Set Radio
 Remler
Model No. 36 DualWave AutoRadio

StrombergCarlson No. 82 AllWave Receiver

Majestic A.V.C. Model 290 Chassis
 FADA 9 Tube
Model 190 "Metal" AllWave
 RCA Victor
Models 9T and K2 9Tube, 5 to 566Meter

Motorola "Golden Voice" Model

RCA Victor Model H6

Simplex Model TA

Automatic "Magic Eye" Model A1
 Silvertone
Models 4488 and 4588 (Chassis No.101412) and 4488A and 4588A (Chassis No. 101412A)
 RCA Victor
Model M109 "De Luxe" 7Tube AutoRadio Receiver
 Crosley Model
6625 6Tube 3Band Receiver
 International
Model 77 Series 7Tube DualBand Receiver
 Belmont
Model 6D121

General Electric Models 60, 62
 Admiral
Model 7C64

Radiola "28" Super and "104" Power Speaker
 Sonora
Model TW49

StrombergCarlson Models 1020, 1120, Series 10
 Air King
Model 4604D
 Sparton Models
526, 526X, 526PS
 Truetone
Model D2624
 Admiral
Models 6EI, 6EIN
 Detrola Models
571A, 571B

General Electric Model 250
 Howard Model
920
 Colonial
Model 652 5Tube BroadcastShortWave

FairbanksMorse
9Tube AllWave Model 91

International Model 500 5Tube DualRange Battery
 Emerson Model
678 "AutoDynamic" 5 Tube

StrombergCarlson
Nos. 230 and 231 Series
 Atwater
Kent Model 649 AllWave

Howard Model G26, and "Airplane 4" Model AA25

Montgomery Ward "Airline" Series 7GM 7Tube HighFidelity Receiver
 RCA
Victor Model T52 5Tube, 2Band A.C. Superheterodyne Receiver

Majestic
"Models 50," "51" and "52"

BremerTully Model 770 and 771

General
Electric Model M49 4Tube RadioPhonograph DualWave Superheterodyne
 RCAVictor
Radiola "Superette" Model R7 Superheterodyne
 Crosley Model AC7
and AC7C

Westinghouse
"Columnaire" Models WR8 and WR8R (Remote Control)

Characteristics
of Metal Tubes  and Other "Octal" (8Prong) Base Types
 Kolster K20,
K22, K25, K27 and K37 SixTube Receivers

StrombergCarlson
Nos. 62 and 63, 8Tube HighFidelity Chassis
 RCA Model
103, 4Tube A.C. Compact DualWave
 FADA "Special"
Model 265A and FADA "7" Model 475A

General Electric Model C62 6Tube Battery
 Emerson
5A Automotive
 Zenith
666 Automotive
 Motorola
100 Automotive

Crosley
Roamio 4A1 Automotive

AmericanBosch
524A Automotive
 Crosley
Model 1316 (in Model 167 Console)
 RCA Victor
"HighFidelity Electrola," Model R99
 AMRAD
Model 81 ("Bel Canto" Series) Receiver

Fada 103 Fadalette, StewartWarner Series 108, DeWald 54 Dynette Sets
 RCA
Victor R27 and Philco 53 UltraMidget A.C.D.C. Radio Receivers

Majestic Models Fairfax and Sheffield 8Tube
 StrombergCarlson
No. 29, 9Tube Superhet

International Kadette Model 400 4Tube BatteryOperated Superhet
 RCA Victor
Model 5M 5Tube Auto Superhet

Majestic Model 11 ShortWave Converter

SilverMarshall
Model 727DC BatteryOperated Superheterodyne
 RCA
Victor Model VHR307 Home Recording  PhonoRadio Combination

Delco 32Volt Radio Receiver Chassis Models RA3, RB3 and RC3
 Majestic
Chassis Models 380 A.C. T.R.F., and 400 A.C.D.C. Superheterodyne
 General
Motors S1A, S1B
 Admiral
Model 7C63, Chassis 7C1
 Westinghouse
Model H133
 Arvin
Models 150TC, 151TC
 Kadette Model
90 Duplex

RCAVictor "Magic Brain" Model 281
 Grunow
11A Chassis 11Tube AllWave Superheterodyne

Sears, Roebuck & Co., Silvertone "Rocket" Models 6110 and 6111

General Electric Model GD52

Zenith Models 6D302, 6D311, 6D326, 6D336, 6D360

Allied Radio, Knight Model E10913
 Arvin Model
140P
 Emerson
Models 501, 502, 504
 Crosley
Model 56TDW
 Hoffman
Model A500

StewartWarner
Model 9003B

Zenith Models 6D014, 6D029
 Coronet
Model C2
 Sparton
Models 746, 746PA, 846, 846PA

StewartWarner Models 9001C, D, E, F

Zenith Models 5D0115D027
 Bendix Models
636A, C, D
 ECA Model 108

International Model 66 and 666, 6Tube Superhet

FordPhilco
Radio, Model FT9, 6Tube AutoRadio Receiver
 Howard
Explorer Model W Deluxe 19 Tube AllWave Superhet
 RCA Victor
Portable Table Electrola Model R95
 Atwater
Kent Model 305Z 5Tube 32 V. D.C. Superhet
 Kadette
Jewel Model 40 Chassis 3Tube UltraMidget Receivers

General Electric Model N60 6Tube Auto Superheterodyne

Sparton Model 40 6Tube T.R.F. Automotive Receiver

Clarion "Replacement" Chassis, Model AC160 A.V.C. Superheterodyne
 Emerson Models
20A and 25A
 General
Electric K40A
 Pilot Model
B2
 RCAVictor
Radiola Model M30 Automotive Radio
 Motovox
Models 10A AllElectric and 10E BatteryOperated "MotoTetradynes"

Kennedy Superheterodyne ShortWave Converter
 RCA
Victor Model R78 B1Acoustic 12Tube
 Philco
Model 15 Series, 11Tube Superheterodyne Chassis

Zenith Challenger Model 740

Sparton
Selectronne Receivers Models 1068 and 1068X
 Fada Model
155 Super Fadalette A.C.D.C. Set

Clarion De Luxe Models AC280 and 25280

Crosley Model A157 (River Roamio) Auto Radio
 Philco Model
'37116 Codes 121 (Shadometer) and 122 (Dial Tuning)

Arvin Model 28

Philco Model 818

Fada Model 266 Motoset

Bosch Models 736, 737, 738
 RCAVictor
Model 15U, RadioPhonograph
 Sparton
Models 566 ("Bluebird" Mirror), A.C.D.C. 5Tube 2Band Midget Superhet
 Atwater
Kent Model 776 6Tube Auto Radio
 StrombergCarlson
No. 61 4Band 7Tube A.C.D.C. Receiver
 Arvin Model
182TFM
 Crosley
Model 58TK
 Westinghouse
Model H165

General Electric Models G105 and G106
 Silvertone
"F," "FF," "G," "H," and "J"

StewartWarner Model 035A1 to 035A9 (Chassis 035A) Senior Varsity Radio
 Radiola Models
616, 617

Westinghouse
Models H104, H105, H107, H108
 Farnsworth
Models EC260, EK262, EK263, EK264, EK265

United
Models 980744, 980745

StewartWarner (R127 Chassis) Models 1271 to 1279 AllWave
 ERLA Model
4500 DualWave T.R.F. 4Tube A.C. Receiver
 Clarion No. TC31
5Tube A.C.D.C. Superhet.
 Detrola Model
105C 5Tube DualBand A.C.D.C.
 Zenith
6Tube AllWave Chassis No. 5634
 RCA Victor
Model 261, 555 to 107 Meter
 Philco
Model 38116; Code 125

StewartWarner "Ferrodyne" Chassis Model R136

AmericanBosch
Model 43OT 5Tube 3Band Superheterodyne
 RCA
Victor Model C94 9Tube 3Band Superheterodyne
 Kennedy "Model
826B" Combination Receiver
 Steinite
50A and 102A
 Pilot Model
63 AllWave 6Tube Superheterodyne
 StrombergCarlson
No. 69 4Tube AllWave Superhet. Selector (Converter)
 RCA
Victor Model 102 4Tube A.C.D.C. T.R.F. Receiver
 Bosch Models 60
and 61

Atwater Kent Models 30, 33, 35, 48 and 49
 Crosley Model
120 Senior Superheterodyne (Pliodynatron) Chassis

Columbia ScreenGrid 8 Receiver

General Electric Models A82 and A87, 8MetalTube AllWave A.C. Superhet.
 Colonial
31 and 32 D.C.
 Zenith 5Tube
TripleWave Chassis nos. 5508 and 5509
 Remler Model
46 ("Scottie")
 General
Electric FA60 and FA61

StewartWarner
Series 900

Howard
Model B5 (715), Series 1 and 2 (Sheaffer RadioClockPen Desk Set)

FordPhilco CarRadio Models F1440 and F1442

Brunswick Model 31 Combination Radio and Panatrope
 Emerson Models
38, 42 and 49, 6Tube DualWave (Chassis U6)

General Motors Chevrolet No. 601574 Automotive

RCA Victor M104 (and M108) Automotive
 ArvinFord
17A Automotive

Westinghouse Model WR 207 & WR 208 5Tube DualBand Superheterodyne
 Radiolas
"Super VIII" (AR810, "SemiPortable" (AR812), 24 and 26
 Howard Model
45 A. V. C.
 Majestic
Model 25

Galvin Motorola Model 61

Arvin Model 6
 Admiral
Models 7T06, 7T12
 Garod Model 5A1
 Hoffman Model A301

Knight Model E10716 Battery Portable
 Arvin Models 555,
555A, 552N, 552AN
 Grantline Models
605, 606
 Truetone Model
D2616
 Belmont Model
5D128
 Arvin Models 444,
444A

International Kadette Model 1019

StewartWarner Models 97561 to 97569
 General
Electric Model 280
 Zenith Models 5R080,
5R086
 Truetone Models
D1747, D1748

Crosley Roamio Automotive T.R.F. Models 90, 91, 92

Crosley Roamio Automotive Superheterodyne Models 95, 96

WellsGardner Series 062

Emerson
Model AZ196
 Belmont Model
5P19
 Crosley
Fortyfive
 Crosley Model
56FC

Emerson
Models 507, 509, 518, 522, 535
 Garod Model 6AU1
 General
Electric Models 219, 202, 221

Crosley "Chairside" Model 567

Belmont Model 408 Battery "Farm"
 Wards Model
74BR1055A
 Farnsworth
Models EK081, EK082, EK083, EK681
 Philco
Model 200X Radio

Admiral "Aeroscope" Models 1615L, 1625L and 1635L
 Philco
Model 59, 4Tube A.C. Midget Superheterodyne
 Zenith
Farm Model 6V 27, 6Tube Superhet
 Ward 10Tube
AllWave HighFidelity Superhet, Series ODM

PhilcoPackard
Deluxe

Canadian
Westinghouse Model 175
 Crosley Model
1155
 Philco Models
39 and 39A

Arvin Model 35 8Tube CarRadio
 Hetro
AirAce Series M
 Westinghouse
Models H161, H168, H168A
 Garod Model 5A4
 Arvin Models 152T,
153T
 Belmont Model 5240
 Mantola Models 92505,
92506
 General Electric
Models 102, 102W, 107, 107W, 114, 114W, 115, 115W
 Crosley Model
555 (A.F.M.)
 Crosley Model
515 (Fiver)
 Crosley Model
425 (Travo)

FirestoneStewartWarner Model R1332
 FairbanksMorse
Model 81 "Farm" Set
 Clarion Model
423, 470, 471, 472, 480

International Radio Corp. Model 90
 Belmont Model
578 Series A
