Bosch Models 60 and 61 Radio Service Data Sheet
August 1931 Radio-Craft

August 1931 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.

This Radio Service Data Sheet for the American Bosch Models 60 and 61 was published in the August 1931 issue of Radio-Craft magazine. I searched high and low on the Internet for a photo of an actual radio. Models 5, 28, 30, 48, and 200 are aplenty, but alas, no 60 or 61. Features like automatic volume control (AVC) were considered deluxe niceties available to the consumer willing to pay extra for it. There are five vacuum tubes in the signal path, not including a separate tube for the AVC circuit. Two rectifier tubes are in the power supply, and a neon bulb is used as a power on indicator. With this number of tubes, it could be either a high-end tabletop job or a console type floor model. Bosch was first a German electronics company before expanding to America.

Bosch Models 60 and 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 con-trolled 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 25, 2023
(updated from original post on 10/5/2016)

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 227 Radio Service Data Sheets as of December 28, 2020.

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Bosch Models 60 and 61 Radio Service Data SheetAugust 1931 Radio-Craft

Bosch Models 60 and 61 Radio Service Data Sheet
August 1931 Radio-Craft