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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 World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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Crosley Model A-157 (Fiver Roamio) Auto Radio
Radio Service Data Sheet
October 1937 Radio-Craft

October 1937 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.

Installing radios in cars and trucks was big business in the 1930s. Most cars of the day did not include a radio as standard equipment. In fact, the most challenging aspect of installing a radio in an automobile was the antenna and tuning mechanism. Electronics magazines of the era - Radio-Craft, Short Wave Craft, et al - had photos of technicians with equipment spread all over the public sidewalks next to where the car having the radio installed is parked. Yep, the car radio installers came to your location like the guys who replace windshields. This photo of the Crosley Model A-157 Fiver Roamio auto radio was found on he RadioMuseum.org website.

5-Tube Superheterodyne; Automatic Volume Control; Direct Tuning

The Fiver Roamio direct-tuning, auto-radio superheterodyne. The power supply and speaker are self-contained, the latter being mounted on the left side of the housing.

The Crosley Model A-157 auto-radio set is a single unit, 5-tube super-heterodyne receiver. incorporating A.V.C. and many advanced features in circuit design. The power supply unit is an integral part of the receiver chassis and uses a primary-type vibrator.

Tubes and Voltage Limits. The following table gives the functions.. of the tubes used, together with the, voltage readings between the tube socket contacts and the receiver chassis. Voltage readings taken with a 1,000 ohms/volt, 500-V, voltmeter (except filaments) with receiver in operating condition and no signal input.

Connect the output meter to 3 and 4 of the 6K6G output tube socket. Be sure the meter is protected from D.C. by connecting a condenser (0.1-mf. or larger - not electrolytic) in series with one of the leads.

1.Tuning I.F. Amplifier to 455 kc

(a) Connect the output of the signal generator through a 0.02-mf. or larger. condenser to the top cap of the 6A8G Osc.-Mod. tube, leaving the tube's control-grid clip in place. Connect the ground lead from the signal generator to the receiver chassis frame. Keep the generator leads ' as far as possible from the control-arid: leads of the other screen-grid tubes.

Posted August 24, 2017

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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Crosley Model A-157 (Fiver Roamio) Auto RadioRadio Service Data Sheet October 1937 Radio-Craft

5-Tube Superheterodyne; Automatic Volume Control; Direct Tuning

Crosley Model A-157 (Fiver Roamio) Auto Radio
Radio Service Data Sheet
October 1937 Radio-Craft