12-17-2022, 02:09 PM
I just finished resurrecting a Truetone Tiny Four from about 1938. It's a portable with 90 (2x45s) and 1.4 volt batteries, no model number so I located a Truetone D1020 that has the same chassis and matched the wiring. One of the major problems was the open primary in the oscillator transformer. I was unable to find a visible break and knowing that AES has a universal replacement I wasn't much interested in rewinding the original. So I ordered one and when it arrived I followed the diagram that closely matched the Truetone circuit. After wrestling with the 1A7 oscillator tube the radio came to life. Soon discovered the band was badly shifted and no matter how much I adjusted the oscillator trimmer and coil slug it wouldn't bring it close enough. Had to double check all parts and connections then decided on trial and error with a fixed capacitor across the oscillator trimmer. Ended up with a 33pf, which gave a slightly spread-out band (830 is at 800 and1500 is about 1530) but the owner is happy with that. So now he can show nieces and nephews what great grandma and grandpa listened to back in the day. I did try an oscillator coil from a parted-out radio but it didn't function at all. AES produced a good one.
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