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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December 1936 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.
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.
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 156 Radio Service Data Sheets as of December 6, 2016.