RCA Victor "High-Fidelity Electrola," Model R-99
Radio Service Data Sheet
December 1936 Radio-Craft

December 1936 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.

In the R-99, a new magnetic pickup is used; the magnet is welded to the pole-pieces; the short, light, centered armature has a viscoloid block attached to the center as a "mechanical filter," to make the frequency response more uniform. It can be removed and a new one fastened in place by heat, best applied with a special-tip soldering iron. The pickup feeds into a compensator pack with filters to correct the frequency response; the output, through the volume control, is divided between V1. the "expander," and V5, the "expander-amplifier.

Amplification is continued through the driver tube V2, impedance-capacity coupled to the primary of its output transformer to increase fidelity, since no plate current flows in the primary. The tone control R1 (incorporated in the switch) across the push-pull stage (V3- V4) permits the user to suit his personal preference in the output. The undistorted output (class A push-pull) of this 3-stage amplifier is rated at 12 W.

RCA Victor "High-Fidelity Electrola," Model R-99

Posted May 25, 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 255 Radio Service Data Sheets as of April 30, 2025.

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