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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 tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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International Model 77 Series (77-777-778-779) 7-Tube Dual-Band Receiver
Radio Service Data Sheet
June 1936 Radio-Craft

June 1936 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.

Seeing a photo of the International Model 77 'Kadette' radio reminds me of the exaggeratedly large heads of invaders in alien attack sci-fi flicks. It has to do with the small dial buried amongst the relatively large cabinet. ...but that's just me. I'm sure it was a fine radio. The thumbnail image of the International Model 77 'Kadette' radio is from the RadioMuseum.org website. Below is the Radio Service Data Sheet as it appeared in a 1936 issue of Radio-Craft magazine.

International Model 77 Series (77-777-778-779) 7-Tube Dual-Band Receiver Radio Service Data Sheet

Ranges: 550 to 1,600 kc, and 5,500 to 15,500 kc. (19 to 55 meters); ballast tube; airplane dial; impregnated coils.

A 15 per cent variation is permissible in these values.

Some of these sets have a 25,000-ohm resistor between the plate resistor of V3 and the coupling condenser.

The 3 trimmers on the bottom of the chassis are, reading from the end of the chassis to the center, broadcast oscillator, short-wave detector, and short-wave oscillator. No trimmer is used across the B.C. detector coil.

The I.F. alignment is made with the service oscillator connected directly to the antenna, adjusting the first, then the second units. Then feed a very weak 1,400 kc, signal to the antenna, and, with the set dial at 1,400 kc., adjust C4 for maximum" Resonance at 1,000 kc, and 600 kc. should be checked, and any needed adjustment made by bending the plates on C6. Short-wave adjustment is made at 15.5 me, at which point C3 is adjusted. Next go to 12 me. and adjust C2. At 6 mc., alignment is made by spreading or crowding turns on the S.W. detector coil.

Posted June 20, 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.

RIGOL Technologies (test equipment) - RF Cafe

International Model 77 Series (77-777-778-779) 7-Tube Dual-Band ReceiverRadio Service Data SheetJune 1936 Radio-Craft

International Model 77 Series (77-777-778-779) 7-Tube Dual-Band Receiver Radio Service Data Sheet

International Model 77 Series (77-777-778-779) 7-Tube Dual-Band Receiver
Radio Service Data Sheet
June 1936 Radio-Craft