RF Cafe Software
About RF Cafe
1996 - 2022
BSEE - KB3UON
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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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January 1939 Radio-Craft[Table of Contents]
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 from Radio-Craft.
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.
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.
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 trimmer. 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 185 Radio Service Data Sheets as of April 12, 2017.