Alignment Problem

[Les Dickson]

I have a Philco 57-123 with an alignment problem. I can hear the station at 540 all across the dial. This is not a local station, it’s relatively weak signal compared to local stations. When I turn the tuner to a local station – 900 – the signal from 540 disappears and the signal from 900 comes in clearly; the same with other relatively local stations.

Following the alignment procedure doesn’t fix the problem.

1. The IFs adjust nicely with the signal generator at 460 and the tuning capacitor fully meshed as instructed with the signal generator through a 0.1 mfd cap to pin 6 of the converter (7A8)
2. At the high end (signal generator at 1600 and dial at 1600) I get the strongest reading with oscillator trimmer so wide open the screw comes out.
3. In the final step – signal generator at 1500, radio dial at 1500 – through 100 mmf to aerial connector – the signal does not strengthen or weaken when adjusting the turner trimmer

Any suggestions are greatly appreciated

Attachments:

1. Philco-57-123.pdf

[Gordon Dann]

sounds like you may have a local oscillator trouble – put a volt meter on pin 7 of the 7a8 and you should get about neg 5v on pin 4 – if not check the osc. coil for opens – also you may be tuning the ifs to a harmonic. if you still have trouble the best thing is for you to call and I can walk you through.good luck Gordon Dann 250-334-2422

[Les Dickson]

Thanks for your reply, Gordon. By playing with the adjustments I got rid of the 540 signal across the dial. The tracking is still off somewhat but I haven’t had a chance to do anything more with the radio. I may still get back to you when I have a chance to work on it again.

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