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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 typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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Colonial Model 652 5-Tube Broadcast Short-Wave Superhet
Radio Service Data Sheet
March 1935 Radio-Craft

January 1939 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.

For many years now I have been scanning and posting Radio Service Data Sheets like this one featuring the Colonial Model 652, 5-tube broadcast short-wave superheterodyne radio receiver for many years now. 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 real-life Colonial Model 652 was found on the radiomuseum.org website.

Colonial Model 652 5-Tube Broadcast-Short-Wave Superhet Radio Service Data Sheet

The tubes and their functions are: 6A7- Oscillator and Det. 1; 78-I.F.; 75-A.V.C.-Det. 2-A.F. 1; 42-output A.F. 2; 80-rectifier.

In order to prevent interference from 600- meter code stations, when the receiver is located near the coast, a wave-trap is incorporated in the antenna circuit. Although this trap is shown in the diagram as a coil with a condenser (L-C), actually it consists of two multi-layer coils wound on top of each other with one end of' each coil unconnected.

The voltage drop across the 0.5-meg. volume control, due to the diode current of the 75 tube, is used for A.V.C. voltage.

Alignment Procedure

The I.F. Stages: (1) Set the service oscillator to 450 kc. and tune the R.F. transformers. (1) Couple test oscillator to green antenna lead, leaving antenna connected. (2) Set the service oscillator to 1,560 kc. (3) Screw the oscillator padder condenser to approximately three-fourths maximum capacity. (4) Turn tuning condenser all the way out. Adjust oscillator trimmer for maximum output. (5) Set the service oscillator to 1,400 kc. and tune in its signal. Then adjust the Vl trim-mer. on the variable condenser nearer the dial, for maximum output. (6) Set service oscillator to 600 kc. and tune in its signal. Then slowly rotate variable condenser and adjust padder.

Posted February 2, 2017

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.

LadyBug Technologies LB5944A RF Power Sensor - RF Cafe

Colonial Model 652 5-Tube Broadcast Short-Wave SuperhetRadio Service Data SheetMarch 1935 Radio-Craft

Colonial Model 652 5-Tube Broadcast-Short-Wave Superhet Radio Service Data Sheet

Colonial Model 652 5-Tube Broadcast Short-Wave Superhet
Radio Service Data Sheet
March 1935 Radio-Craft