1996 - 2016
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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August 1931 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.
This Radio Service Data Sheet for the RCA-Victor Radiola "Superette" Model R7 Superheterodyne was published in the August 1931 issue of Radio-Craft magazine. The Model R7 is a tabletop, or "mantel," radio set that is the first of its kind for RCA-Victor. It is fairly large at 14 x 19 x 10 inches, and weighs 37 pounds, per data on the RadioMuseum.org website.
The circuit of this receiver is of particular interest, as being the first of the mantel radio sets brought out by these companies. It is seen, by reference to the diagram below, that this superheterodyne uses a limited number of tubes, in the following manner: One stage of signal-frequency R.F., V1, using the new type '35 variable-mu tube; a type '27 as oscillator, V2; a '24 screen-grid first-detector V3; a type '35 variable-mu first stage of I.F. amplification, V4; a type '27 power second detector, V5; push-pull '45's, V6, V7, in the power A.F. circuit; and the usual '80 rectifier V8.
The resistance values of the choke coils and transformers in this model chassis are shown in parentheses in the diagram (Fig. I); other constants are given below.
Posted October 5, 2016
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.