I am not specifically fsmiar with the SX-71 but this seems excessive. Certainly mechanical. Could be the oscillator tube? or more likely something loose.? Check the tuning cap and tube by tapping around with the eraser end of a pencil.? Can also be a cold solder joint or even an unsoldered joint. Also look for cracked resistors.? Have you already cleaned the band switch and cap wipers???
? ?Is this a new problem?? Does it jump in SSB?? Should be the same in both modes.? It's probably doing it in AM but will be harder to hear.
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-------- Original message --------
From: John Green <radio1956@...>
Date: 1/12/23 7:54 PM (GMT-08:00)
Subject: [HallicraftersRadios] SX-71 frequency shift
The SX-71 I am working on is tuned up and operating fine. However, when operating cw, the frequency shifts as much as 400 Hertz if the table is bumped or radio tapped.
Even after good warm up and drift stabilizes, shift is readily induced.
Any suggestions for fix much appreciated.
Best 73,
John, kx4p?
