RCA-Victor Radiola Model M-30 Automotive Radio Set
Radio Service Data Sheet
April 1932 Radio-Craft

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

This Radio Service Data Sheet for the RCA-Victor Radiola Model M-30 Automotive Radio Set is an example of the dozens of similar schematic and alignment instruction sheets that have been posted on RF Cafe over the years. It was published in a 1932 issue of Radio-Craft magazine. Obtaining technical information on most things, even readily available items, prior to the Internet era was often very difficult - if not impossible. Service centers had what was needed provided by manufacturers and distributors, but if you wanted to find a part number or service data on a refrigerator, radio, lawn mower, garage door opener, etc., and did not have the original paperwork, you were usually out of luck. Nowadays a Web search will quite often get you what you need thanks to people (like me) who go to the trouble of making the information available. The stuff doesn't just magically appear or get posted by benevolent governmental entities. You're welcome.

RCA-Victor Radiola Model M-30 Automotive Radio Set Radio Service Data Sheet

(Automatic Volume-Control - Push-Push Power Amplification - 9 Tubes)

Automotive radio receivers have been undergoing a change, with the primary objective of obtaining in automobiles comparatively the same over-all efficiency which exists in the less mobile "home" installation. A close approach to this degree of perfection is obtained from the Radiola Model M-30 receiver, manufactured by RCA-Victor Co., Camden, N. J.

The values of the components of this receiver model are as follows:

Condensers Ct , C2, C3, tuning condensers, 18-325 mmf.; C1A, C2A, C3A, trimmers, 4-50 mmf.; C4, padding condenser, 720 mmf.; C4A, padding trimmer, 10-75 mm£.; C5, trimmers, 15-75 mmf.; C6, trimmers, 140-220 mmf.; C7, 745 mmf.; C8, C10, 0.25-mf.; C9, C11, C12, 0.1-mf.; C13, C14, 0.0024-mf.; C15, C16, 0.5-mf.; C17, 4 mf.; C18, C19, 0.018-mf.

Resistor R1, 10,000 ohms; R2, 6,000 ohms; R3, 40,000 ohms; R4, R5, 30,000 ohms; R6, 170 ohms; R7, 0.5-meg.; R8, 28,000 ohms; R9, 0.1-meg.; R10, 1.0 meg.; R11, 3,500 ohms; R12, 4 ohms; R13, R14, 270 ohms; R15, 1,200 ohms; R16, 70,000 ohms; R17, 50,000 ohms.

The Model M-30 receiver has been designed with particular regard to ease of installation and service. Properly installed, freedom from interference should be experienced with the receiver operating at full sensitivity. Approximate operating voltage and current values (obtained on a Weston Model 547 test set), taken with the volume control set at the "minimum" and "maximum" (maximum values shown in parentheses) positions are as follows:

Filament potential, V1 to V6, V9, 6 volts; V7, V8, 4.5 volts. Cathode-to-heater potential, V1, V4, 18 volts; V2, 1.0 volt; V3, 6 volts; V5, 12 volts; V6, 15 volts; V9, 10 (5) volts. Control-grid-to-cathode (or filament) potential, V1, 0.5-volt; V2, 3 volts; V3, zero; V4, 1.0 (0.5) volt; V5, 10 volts; V6, 2 volts; V7, V8, 20 volts; V9, 1.0 (9) volts. Screen-grid-to-cathode potential, V1, V4, 100 (70) volts; V2, 42 volts. Plate-to-cathode (or filament) potential, V1, V4, 136 (135) volts; V2, 150 volts; V3, 45 volts; V5, 110 volts; V6, 165 volts; V7, V8, 155 volts; V9, 15 volts. Plate current, V1 ,V4, zero (4 ma.); V2, 0.25-ma.; V3, V6, 3.5 ma., V5, 0.5·ma.; V7, V8, 1.5 ma.; V9, zero. Screen-grid current, V1, V4, zero (1.0 ma.); V2, 0.1-ma.

Automatic volume-control tube V9 is connected to the cathode circuit of second-detector V5. The change in the bias voltage of V5, due to fluctuation of the signal, is applied to the control-grid of V9, resulting in a drop across plate resistor R7 which constitutes the control-grid bias for the R. F. and I.F. tubes. As the value of the plate current in a tube is a direct result of the voltage applied to the grid, a greater plate current in V9 gives a greater voltage drop across the resistor in its plate circuit and therefore a higher bias on the I.F. and R.F. stages, resulting in less sensitivity, and vice versa; previous A. V.C. systems have operated on different principles. Manual volume-control resistor R17 varies the bias on the control-grid of V9.

The total "A" current is 2.85 amps.; "B," 12 ma. min., and 25 average max. The power output rating of' this receiver is 2 watts. This high rating is a result of "push-push" (or class B") power output, which has been described in detail in past issues of Radio-Craft; notably, the January and February, 1932 issues.

To adjust these circuits, dismount the chassis but do not remove its connections or the flexible cable. Balance the R.F. circuits at 1400 and 600 kc., using a No. 5 Spintite, and an insulated screw driver. When the dial indicates 150, the tuning condensers should be fully meshed. Padding condenser C4 comes into consideration when the 600-kc. adjustments are being made; its trimmer C4A is then adjusted, while the main condenser gang is rocked back and forth for maximum deflection on the output test meter. During these adjustments, V9 must be removed from its socket.

For the I.F. adjustments, at 175 kc., it is also necessary to remove the chassis from its mounting brackets.

Insufficient volume-control by means of R17 may be due to the use of a tube of wrong constants for V9.

In the receiver, the tubes are arranged in two rows. In one (left to right) they are:

V3, V2, V1, V4, V5, V8; in the other: V9, V6, V7.

Posted July 26, 2023
(updated from original post on 8/7/2015)

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 no-cost bonus for readers. There are 227 Radio Service Data Sheets as of December 28, 2020.

• AMRAD Model 81 "Bel Canto"
• GE Model 250 Radio Service Data Sheet
• Hoffman Model A300
• Emerson Model 505
• Olympic Models 6-501, 6-502, 6-503
• Radiola Models 61-5, 61-10
• Farnsworth Models ET-060, ET-061, ET-063
• General Electric Model 321
• Garod Model 6AU-1
• Truetone Model D4620
• Westinghouse Model H-148
• Wards Models 54BR-1501A, 1502A
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• RCA Models Q22A, Q32
• Zenith Model 5G003ZZ
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• Wards Model 74BR-2707A
• Crosley Model 56TP-L
• 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, 54B-N, 54B2, 54B3 Radio Data Sheet 335
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• RCA Victor Model H-6
• 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" 7-Tube Auto-Radio Receiver
• Crosley Model 6625 6-Tube 3-Band Receiver
• International Model 77 Series 7-Tube Dual-Band Receiver
• Belmont Model 6D121
• General Electric Models 60, 62
• Admiral Model 7C64
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• Sonora Model TW-49
• Stromberg-Carlson 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
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• Fairbanks-Morse 9-Tube All-Wave Model 91
• International Model 500 5-Tube Dual-Range Battery
• Emerson Model 678 "Auto-Dynamic" 5 Tube
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• Montgomery Ward "Airline" Series 7GM 7-Tube High-Fidelity Receiver
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• 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
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• Stromberg-Carlson Nos. 62 and 63, 8-Tube High-Fidelity Chassis
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• FADA "Special" Model 265-A and FADA "7" Model 475-A
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• American-Bosch 524A Automotive
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• Kadette Model 90 Duplex
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• Grunow 11A Chassis 11-Tube All-Wave Superheterodyne
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• General Electric Model GD-52
• Zenith Models 6D302, 6D311, 6D326, 6D336, 6D360
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• Arvin Model 140P
• Emerson Models 501, 502, 504
• Crosley Model 56TD-W
• Hoffman Model A500
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• Zenith Models 6D014, 6D029
• Coronet Model C-2
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• Stewart-Warner Models 9001-C, D, E, F
• Zenith Models 5D011-5D027
• Bendix Models 636A, C, D
• ECA Model 108
• International Model 66 and 666, 6-Tube Superhet
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• Howard Explorer Model W Deluxe 19 Tube All-Wave Superhet
• RCA Victor Portable Table Electrola Model R-95
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• Sparton Selectronne Receivers Models 1068 and 1068X
• Fada Model 155 Super Fadalette A.C.-D.C. Set
• Clarion De Luxe Models AC-280 and 25-280
• Crosley Model A-157 (River Roamio) Auto Radio
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• Arvin Model 28
• Philco Model 818
• Fada Model 266 Motoset
• Bosch Models 736, 737, 738
• RCA-Victor Model 15U, Radio-Phonograph
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• Atwater Kent Model 776 6-Tube Auto Radio
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• Arvin Model 182TFM
• Crosley Model 58TK
• Westinghouse Model H-165
• General Electric Models G-105 and G-106
• Silvertone "F," "FF," "G," "H," and "J"
• Stewart-Warner Model 03-5A1 to 03-5A9 (Chassis 03-5A) Senior Varsity Radio
• Radiola Models 61-6, 61-7
• Westinghouse Models H-104, H-105, H-107, H-108
• Farnsworth Models EC-260, EK-262, EK-263, EK-264, EK-265
• United Models 980744, 980745
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• Detrola Model 105C 5-Tube Dual-Band A.C.-D.C.
• Zenith 6-Tube All-Wave Chassis No. 5634
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• Philco Model 38-116; Code 125
• Stewart-Warner "Ferrodyne" Chassis Model R-136
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• RCA Victor Model C9-4 9-Tube 3-Band Superheterodyne
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• Pilot Model 63 All-Wave 6-Tube Superheterodyne
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• 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
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• Columbia Screen-Grid 8 Receiver
• 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 and FA-61
• Stewart-Warner Series 900
• Howard Model B-5 (715), Series 1 and 2 (Sheaffer Radio-Clock-Pen Desk Set)
• Ford-Philco Car-Radio Models F-1440 and F-1442
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• Emerson Models 38, 42 and 49, 6-Tube Dual-Wave (Chassis U6)
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• Arvin-Ford 17-A Automotive
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• 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
• Stewart-Warner Models 97-561 to 97-569
• 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
• Wells-Gardner Series 062
• Emerson Model AZ-196
• Belmont Model 5P19
• Crosley Fortyfive
• Crosley Model 56FC
• Emerson Models 507, 509, 518, 522, 535
• Garod Model 6AU-1
• General Electric Models 219, 202, 221
• Crosley "Chairside" Model 567
• Belmont Model 408 Battery "Farm"
• Wards Model 74BR-1055A
• Farnsworth Models EK-081, EK-082, EK-083, EK-681
• Philco Model 200-X Radio
• Admiral "Aeroscope" Models 161-5L, 162-5L and 163-5L
• Philco Model 59, 4-Tube A.C. Midget Superheterodyne
• Zenith Farm Model 6V 27, 6-Tube Superhet
• Ward 10-Tube All-Wave High-Fidelity Superhet, Series ODM
• Philco-Packard Deluxe
• Canadian Westinghouse Model 175
• Crosley Model 1155
• Philco Models 39 and 39A
• Arvin Model 35 8-Tube Car-Radio
• Hetro Air-Ace Series M
• Westinghouse Models H-161, H-168, H-168A
• 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)
• Firestone-Stewart-Warner Model R1332
• Fairbanks-Morse Model 81 "Farm" Set
• Clarion Model 423, 470, 471, 472, 480
• International Radio Corp. Model 90
• Belmont Model 578 Series A