April 1933 Radio-Craft
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics.
Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles
As in the past, I am posting these Radio Service Data Sheets
as a service to someone who might be doing research on vintage radios
and/or restoring one. Roamio is not producing automobile radios
anymore, but they do now make
TiVo recorders and streaming media players. The
Crosley Roamio Automotive T.R.F. Receiver Models 90, 91 and 92
was made in the early 1930 at a time when cars and trucks were just
starting to experience such luxury. Crosley
did not begin manufacturing its own line of cars until 1939, so
none of these radios made it into Crosley autos.
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 no-cost bonus for readers. There are 152 Radio Service Data Sheets as of
November 14, 2016.
- Majestic "Models 50," "51"
Model 7-70 and 7-71
- General Electric
Model M-49 4-Tube Radio-Phonograph Dual-Wave Superheterodyne
- RCA-Victor Radiola "Superette"
Model R7 Superheterodyne
- Crosley Model AC-7 and AC-7C
- Westinghouse "Columnaire"
Models WR-8 and WR-8-R (Remote Control)
- Characteristics of
Metal Tubes - and Other "Octal" (8-Prong) Base Types
- Kolster K20, K22, K25, K27 and K37
Nos. 62 and 63, 8-Tube High-Fidelity Chassis
- RCA Model 103, 4-Tube A.C. Compact
- FADA "Special" Model 265-A
and FADA "7" Model 475-A
- General Electric Model
C-62 6-Tube Battery
- Emerson 5A Automotive
- Zenith 666 Automotive
- Motorola 100 Automotive
- Crosley Roamio 4-A-1
- American-Bosch 524A
- Crosley Model 1316 (in Model
- RCA Victor "High-Fidelity Electrola,"
- AMRAD Model 81 ("Bel Canto"
- Fada 103 Fadalette,
Stewart-Warner Series 108, DeWald 54 Dynette Sets
- RCA Victor R-27 and Philco
53 Ultra-Midget A.C.-D.C. Radio Receivers
Models Fairfax and Sheffield 8-Tube
- Stromberg-Carlson No.
29, 9-Tube Superhet
- International Kadette
Model 400 4-Tube Battery-Operated Superhet
- RCA Victor Model 5M 5-Tube Auto
Model 11 Short-Wave Converter
- Silver-Marshall Model
727-DC Battery-Operated Superheterodyne
- RCA Victor Model VHR-307
Home Recording - Phono-Radio Combination
- Delco 32-Volt
Radio Receiver Chassis Models RA-3, RB-3 and RC-3
- Majestic Chassis Models
380 A.C. T.R.F., and 400 A.C.-D.C. Superheterodyne
- General Motors S1A, S1B
- Admiral Model 7C63, Chassis
- Westinghouse Model H-133
- Arvin Models 150TC, 151TC
- Kadette Model 90 Duplex
- RCA-Victor "Magic
Brain" Model 281
- Grunow 11A Chassis 11-Tube
Sears, Roebuck & Co., Silvertone "Rocket" Models 6110 and 6111
Electric Model GD-52
Models 6D302, 6D311, 6D326, 6D336, 6D360
Allied Radio, Knight Model E10913
- Arvin Model 140P
- Emerson Models 501, 502, 504
- Crosley Model 56TD-W
- Hoffman Model A500
- Stewart-Warner Model
- Zenith Models 6D014,
- Coronet Model C-2
- Sparton Models 7-46,
7-46PA, 8-46, 8-46PA
- Stewart-Warner Models
9001-C, D, E, F
- Zenith Models 5D011-5D027
- Bendix Models 636A, C, D
- ECA Model 108
Model 66 and 666, 6-Tube Superhet
- Ford-Philco Radio,
Model FT9, 6-Tube Auto-Radio Receiver
- Howard Explorer Model W Deluxe
19 Tube All-Wave Superhet
- RCA Victor Portable Table
Electrola Model R-95
- Atwater Kent Model 305Z
5-Tube 32 V. D.C. Superhet
- Kadette Jewel Model 40 Chassis
3-Tube Ultra-Midget Receivers
- General Electric Model
N-60 6-Tube Auto Superheterodyne
- Sparton Model
40 6-Tube T.R.F. Automotive Receiver
- Clarion "Replacement"
Chassis, Model AC-160 A.V.C. Superheterodyne
- Emerson Models 20A and 25A
- General Electric K-40A
- Pilot Model B-2
- RCA-Victor Radiola Model
M-30 Automotive Radio
- Motovox Models 10A All-Electric
and 10E Battery-Operated "Moto-Tetradynes"
- Kennedy Superheterodyne
- RCA Victor Model R-78 B1-Acoustic
- Philco Model 15 Series,
11-Tube Superheterodyne Chassis
- Zenith Challenger Model
- Kennedy "Model 826B"
- Steinite 50-A and 102-A
- Pilot Model 63 All-Wave 6-Tube
- Stromberg-Carlson No.
69 4-Tube All-Wave Superhet. Selector (Converter)
- RCA Victor Model 102 4-Tube
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
- Columbia Screen-Grid
- General Electric
Models A82 and A87, 8-Metal-Tube All-Wave A.C. Superhet.
- Colonial 31 and 32 D.C.
- Zenith 5-Tube Triple-Wave Chassis
nos. 5508 and 5509
- Remler Model 46 ("Scottie")
- General Electric FA-60
- Stewart-Warner Series
- Howard Model B-5 (715),
Series 1 and 2 (Sheaffer Radio-Clock-Pen Desk Set)
Car-Radio Models F-1440 and F-1442
Model 31 Combination Radio and Panatrope
- Emerson Models 38, 42 and 49, 6-Tube
Dual-Wave (Chassis U6)
Motors Chevrolet No. 601574 Automotive
- RCA Victor M-104
(and M-108) Automotive
- Arvin-Ford 17-A Automotive
- Westinghouse Model WR
207 & WR 208 5-Tube Dual-Band Superheterodyne
- Radiolas "Super VIII" (AR-810,
"Semi-Portable" (AR-812), 24 and 26
- Howard Model 45 A. V. C.
- Majestic Model 25
Motorola Model 61
- Arvin Model 6
- Admiral Models 7T06, 7T12
- Garod Model 5A1
- Hoffman Model A301
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
Models 97-561 to 97-569
- General Electric Model 280
- Zenith Models 5R080, 5R086
- Truetone Models D1747, D1748
Roamio Automotive T.R.F. Models 90, 91, 92
Roamio Automotive Superheterodyne Models 95, 96
- Emerson Model AZ-196
- Belmont Model 5P19
- Crosley Model 56FC
- Emerson Models 507,
509, 518, 522, 535
- Garod Model 6AU-1
- General Electric Models 219,
"Chairside" Model 567
Model 408 Battery "Farm"
- Wards Model 74BR-1055A
- Farnsworth Models EK-081, EK-082,
- Philco Model 200-X Radio
Admiral "Aeroscope" Models 161-5L, 162-5L and 163-5L
- Philco Model 59, 4-Tube A.C.
- Zenith Farm Model 6V 27,
- Ward 10-Tube All-Wave High-Fidelity
Superhet, Series ODM
- Philco-Packard Deluxe
- Canadian Westinghouse
- Crosley Model 1155
- Philco Models 39 and 39A
- Arvin Model 35
- Hetro Air-Ace Series M
- Westinghouse Models H-161, H-168,
- 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)
- Fairbanks-Morse Model
81 "Farm" Set
- Clarion Model 423, 470, 471, 472,
Radio Corp. Model 90
- Belmont Model 578 Series A
Crosley Roamio Automotive T.R.F. Receiver Models 90, 91 and 92 Radio
Service Data Sheet
(The T.R.F series of Crosley Roamio sets; Radio Service Data
Sheet No. 88 describes the superheterodyne series.)
operating potentials are given below. These values are measured
with the reproducer connected and the tubes in place. For plate
and grid voltages, use a high-resistance meter; measure from tube
element to negative filament.
The A. V .C. potential is derived as the drop across R2. With
increased signal, more current flows through the plate circuit of
the combination detector and A. V. C. tube, V3, increasing the drop
across R2 and thereby increasing the bias voltage applied to the
control-grids of V1 and V2. This results in a reduction of the R.F.
amplification, and thus maintains constant the A.F. output determined
by the setting of R1.
Battery D supplies plate potential for V3. The negative "B" and
positive "C" lead returns to the center-tap of two 25 ohm resistors,
to secure the same plate potentials regardless of whether the car-battery
positive or negative terminal is grounded.
Average operating potentials are given in the tabulation below.
Measure, with a high-resistance meter, to the negative filament
*With volume control "off."
If a signal of sufficient strength is received to cause current
to flow in the grid circuit of V3 (biased by R6), the resultant
drop across R2 decreases the amplification of V1, V2. Resistors
R3, R4, R5 are R.F. filters.
Manual volume control R1 determines the A.F. input to the control-grid
of A.F. amplifier V4.
Operating potentials appear in the table.
The circuit is adjusted for zero current flow in the circuit
of A.V.C. tube V6, with normal signal input; at the same time resistor
R3 establishes the normal bias required by the control-grids of
V1, V2. Now, an incoming signal of increased strength causes diode
V6, in conjunction with load-resistor R2, to develop across R2 an
increased D.C. negative potential which reduces the amplification
of V1, V2. Resistors R4, R5 are R.F. filters.
The A.F. input to the first-A.F. tube, V4, is determined by the
setting of the manual volume control, R1.
Manual volume control resistor R1 has a value of 0.3-meg. Since
Crosley Service Bulletin No. A8 does not include the tube operating
voltages for the model 92, estimated values are given.
At the present time there are no Roamio models 93 or 94 receivers.
Posted January 28, 2015