Sonora Model TW-49 Radio Service Data Sheet
November 1939 Radio-Craft

November 1939 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.

I have been scanning and posting Radio Service Data Sheets like this one featuring the Sonora Model TW-49 radio receiver for many years now. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics and/or tuning information. The thumbnail image of the Sonora Model TW-49 came from the RadioMuseum.org website.

Sonora Model TW-49 Radio Service Data Sheet

5-Tube Superhet.: A.C.-D.C. Operation; Automatic Tuning;. Automatic Volume Control; Tuning Range: 535 kc. to 1,720 kc, (includes 1,712 kc. Police Band); Provision for Television or Phonograph Connection.

Lack of sensitivity and poor tone quality may be due to any one or a combination of causes such as weak or defective tubes or speaker. open or grounded bias resistor. bypass condenser. etc. Never attempt to realign set until all other possible sources of trouble have been first thoroughly investigated and definitely proved not to be the cause.

Correct Alignment Procedure: The inter-mediate frequency (I.F.) stages should be aligned properly as the first step. After the I.F. transformers have been properly adjusted and peaked, the broadcast band should be adjusted.

I.F. ALIGNMENT. With the gang condenser set at minimum, adjust the test oscillator to 456 kc. and connect the output to the grid of the 1st-detector tube (12A8GT) through a 0.05-or 0.1-mf. condenser. The ground on the test oscillator should be connected to the chassis ground. Align all 3 I.F. trimmers to peak or maximum reading on the output meter.

Posted April 12, 2017