[R-390] Xtal Question

[Dennis McLaughlin]

I think the round oven in the back left corner of the RF chassis
is on all the time.  It has the first crystal oscillator (17MHz) and the 
calibrator crystal (200 KHz) in it.  Only the second crystal oscillator 
chassis and the PTO ovens are controlled by the ovens switch on the 
back.  I did a test a while back and the 17MHz oscillator started 342Hz 
high at a cold start and after 47 hours the oscillator was 223Hz high.
The spec is 20ppm or 340Hz.  Mine is running on the high side but still 
within spec after 40 years.  Not bad.  What a great radio.
I guess of you disconnected the oven and realign the RF chassis you 
could use the other crystal.  The stability on the 0-7MHz bands might 
suffer.

Dennis McLaughlin