[SignalOne] CX11A warm up drift

[RZaepfel at aol.com]

Greetings List!
 
My CX11A (late production -- May 1981 according to Paul's reckoning)  
exhibits excessive warm up drift with concomitant readout inaccuracy. From a  cold 
start the readout displays about 400 Hz high and slowly, over about two  hours, 
comes to rest at the correct indication. The radio has the adjustable 10  MHz 
plug-in oscillator board and I know that the 10 MHz is moving with time and  
temperature. I experimented with a resistor glued to the 10 MHz crystal to act  
as a rudimentary oven, it helps, but the drift continues. I replaced the +15 
and  -15 volt regulators recently and checked the synthesizer and bfo. They 
seem to  be at spec. The 34.2 MHz oscillator in the bfo box comes to rest 
quickly as the  oven warms to temperature. It's quite possible that silver micas in 
the 10 MHz  oscillator are getting "old" and moving a bit with temperature 
change. 
 
Your thoughts and experiences are welcome. A TCXO would be a good  
acquisition. Should anyone on the List have a TCXO for the CX11A that they wish  to 
sell, please contact me. 
 
Bob K4HJF




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