[R-390] Capehart made R-390A Serial #312

Karsten Simon karstenpg.simon at web.de
Thu Apr 10 07:53:32 EDT 2025


I am currently working on realignment: checking and tuning Crystal
Oscillator subchassis. Frequencies measured with an accurate  8-digit
digital counter. Everything appears to be ok. One exception: oscillator
output on band 30 is 22 MHz (2nd harmonic), should be 33 MHz (3rd harmonic).
Active crystal is Y403 (11 MHz). Trimmer capacitor C431H appears to be ok.
Output (pin 3 of T401) is in the range of 3 to 5 volts and can be adjusted
by turning C431H. Band 8 (11 MHz osc. output) is ok. Band 19 (22 MHz osc.
output = 2nd harmonic) is ok. Any ideas why band 30 output is 2nd harmonic
and not 3rd?

Regards

Karsten



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