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Stewart-Warner 5-Tube Models 97-561 to 97-569 (Superhet Chassis 97-56)
Radio Service Data Sheet
October 1938 Radio-Craft

October 1938 Radio-Craft

October 1938 Radio Craft Cover - RF Cafe[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.

Stewart-Warner 5-Tube Models 97-561 - RF Cafe

Stewart-Warner 5-Tube Models 97-561 (RadioAttic.com image)

For many years I have been scanning and posting "Radio Service Data Sheets" like this one featuring the Stewart-Warner 5-Tube Models 97-561 to 97-569 (Superheterodyne Chassis 97-56) radio, in graphical format and with some or all of the text after running it through OCR software. Electronics magazines back in the day would publish these for the benefit of servicemen and do-it-yourselfers who did not have access to manufacturer information documentation or could not afford to buy it from independent companies like Sam's Photofact. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics and/or tuning information. The thumbnail image of a beautifully restored example of a Stewart-Warner Model 97-561 came from the RadioAttic.com website (click it for more photos). I keep a running list of all data sheets to facilitate a search (see below).

Stewart-Warner 5-Tube Models 97-561 to 97-569 (Superhet. Chassis 97-56) Radio Service Data Sheet

Stewart-Warner 5-Tube Models 97-561 to 97-569 (Superhet. Chassis 97-56) Radio Service Data Sheet, October 1938 Radio Craft - RF Cafe

Band (540 to 1,720 kc.) 117 Volts, A.C.-D.C.; Pushbutton and Manual Tuning.

Alignment Procedure for Alignment:

An output meter and an accurately calibrated signal generator with a tuning range from 465 kc. to 1,500 kc. are required.

1. Connect the output meter across the voice coil or between the plate of the 25L6G output tubs and ground. depending on the type of meter. (The more sensitive type should be connected across the voice coil.)

2. Connect the ground lead of the signal generator to the chassis of the receiver through a 0.1-mf. condenser and keep it connected in this manner throughout the entire alignment procedure. Failure to do this may have serious results as one side of the power line may be grounded in the signal generator.

3. Turn the volume control to the maximum volume position and keep it in this position throughout the entire alignment procedure.

4. With the gang condenser in full mesh, set the indicator to the last mark on the top end of the dial scale. If the pointer is only slightly off calibration, it may be possible to slip the dial drum just enough to correct for this slight miscalibration. If the dial is several divisions off-calibration, loosen the set screw on the condenser shaft. Then grasp the end of the tuning shaft and turn the dial until the last division of the scale is directly under the indicator, when the gang is in full mesh. Then retighten the set-screw.

Socket Voltages

The voltages shown below are measured between socket terminals (underside view) and chassis unless otherwise shown. Use a high-resistance voltmeter, at least 1,000 ohms/volt. Note A: Bias control for 25L6G control grid is 6V. Due to high resistance in the grid circuit, voltage will read low. Note B: Due to the high resistance in the plate and screen-grid circuits the voltages measured at these terminals will be very small.

 

 

Posted February 4, 2022
(updated from original post on 10/9/2014)


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.

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Copyright: 1996 - 2024

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RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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