Fairbanks-Morse Model 81 2-Band 8-Tube 2 V. "Farm" Set
Radio Service Data Sheet
March 1936 Radio-Craft

March 1936 Radio-Craft

March 1936 Radio-Craft Cover - RF Cafe[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.

Fairbanks-Morse Model 81 2-Band 8-Tube 2 V. "Farm" Set Radio Service Data Sheet

(Ranges - 540 to 1,740 kc., 5.5 to 16 mc.; full A.V.C.; class B output; R.F. stage; new type speaker.

This set has provision for use on either dry cells, storage cell, or air cell. An Amperite 6-1 ballast tube is needed for 3 V. operation. For air-cell use, a resistance link is inserted in the socket provided for it in the set. A jumper link is plugged into the same socket when a storage cell is employed.

Fairbanks-Morse Model 81 2-Band 8-Tube 2 V. "Farm" Set Radio Service Data Sheet, March 1936 Radio-Craft - RF Cafe

When a doublet antenna is used on this set one lead connects to the blue wire, and the other to the blue and black wire.

I.F. alignment is made with the band switch in the broadcast or left-hand position. Supply a 465 kc. signal to the cap of the 1C6 tube and adjust trimmers on first I.F. transformer and then on the second.

R.F. alignment on the broadcast band is made first on 1,400 kc. with the signal fed in through the antenna post. The oscillator trimmer is adjusted first, then the antenna trimmer. Then a 600 kc. signal is used and the oscillator padding condenser adjusted.

Feed a 15 mc. signal to the antenna circuit and, with the dial set at 15 mc., adjust oscillator for highest output. Then set the shortwave R.F. trimmer for best signal with least input from the service oscillator. It is advisable to rock the condenser back and forth across the signal while making this adjustment to make sure the peak of greatest intensity is obtained.

*Anode grid-165 V. All voltages measured from ground with 1,000 ohms-per-volt meter, 300 V. scale.

After re-aligning, it will often be necessary to reset the dial. This is done with the chassis bolted in place. The set-screw in the travelite dial hub is loosened and the dial turned to the correct location.

The speaker may be adjusted by means of the 3 screws on the rear.



Posted July 13, 2015

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 219 Radio Service Data Sheets as of November 15, 2017.