AMRAD Model 81 ("Bel Canto" Series) Receiver
Radio Service Data Sheet
June 1930 Radio-Craft

June 1930 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.

These images of an AMRAD model 81 "Bel Canto" radio images retrieved from eBay.

AMRAD Model 81 ("Bel Canto" Series) Receiver

The AMRAD Model 81 chassis is fused at three amperes. The "antenna compensating control" is the 10-plate variable condenser marked CIA; while while the remaining trimming condensers are adjustable, through the shield can, with a screwdriver. Binding posts at the rear of the chassis permit selection of the correct tap on the antenna input inductance L1 , for the required degree of selectivity and sensitivity. When the tube is renewed at V4, it will probably be necessary to readjust the setting of R8. If circuit oscillation should appear in the receiver, it may usually be traced to a defective '24 tube, which should be replaced. The cord which operates the tuning dial is kept in tension by an adjustment which compensates for stretching; this is regulated by putting a screwdriver through a hole cut in the edge of the dial drum. Each of the R. F. transformer primaries (Ll1, as well as P in L2, L3 and L4) consists of a winding of about 200 turns on a bobbin at the grid end of the secondary; it has a direct-current resistance of about 80 ohms.

The metal placard shown in the eBay radio image reads as follows:

"Licensed only for radio amateur experimental broadcast uses and for electric phonograph reproductions from grooved records. Licensed for use in connection with electric phonograph devices sold or manufactured and sold under license from Radio corporation of America. Except as in their license notice expressly provided the sale of this apparatus confers no license under any any of the foregoing patents or under any other patents under which Radio Corporation of America may have the right to grant licenses to make use or sell any other with resect to broadcast reception and electric phonograph uses licensed only for private use in homes and for entertainment and educational purposes otherwise than in combination or in connection with apparatus in the field of wire telephony or apparatus for projection or production either directly or by electric currents waves or impulses of still or motion pictures. Licensed in Hazeltine and Latour Patents Issued and Pending."

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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AMRAD Model 81 ("Bel Canto" Series) ReceiverRadio Service Data Sheet June 1930 Radio-Craft

AMRAD Model 81 ("Bel Canto" Series) Receiver
Radio Service Data Sheet
June 1930 Radio-Craft