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 Bosch Models 60 and 61 was published in the August 1931 issue of Radio-Craft magazine. Features like automatic volume control (AVC) were considered deluxe niceties available to the consumer willing to pay extra for it. I could not find a photo of the Bosch Model 60 or Model 61.
The Bosch Model 60 receiver incorporates an automatic volume-control tube, V8; a "mute switch" SW4 (which should be closed, during the operation of tuning, to short the voice coil of the dynamic reproducer; thus eliminating the sounds incidental to tuning in programs, the automatic volume control's panel-meter being the resonance indicator) and connections for a phonograph .pickup, The pickup circuit is controlled by an automatic switch, SW2, which, in the tuning dial's "0" position is designed to replace a 1,000-ohm resistor and its bypass condenser by a pick-up of approximately 1,000 ohms, At the same time, a ground spring makes contact with condenser C4; shorting it out of circuit and eliminating the need to de tune the R.F. portion of the receiver.
The trimmer condensers are located on the condenser gang. The antenna coupling condenser C1A is adjusted from the side of the chassis, when the set is installed, in the following manner: tune in a somewhat weak station at some point between 40 and 60 on the dial; reduce the volume until the station can be barely be heard; and then turn the adjustment knob of C1A until the signal is received with maximum volume.
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.