[R-390] 200KC calibration crystal source

[Roy Morgan]

At 05:43 AM 3/30/2007, you wrote:

>I don't think it will hurt the stability of the radio much at all either for
>typical swl and amateur.

Phil,

I agree, though I have not done any tests.

>... Many of us use our  R-390A's with the ovens turned
>off anyway.

You may know that the OVENS switch does not control the little round octal 
plug-in oven that houses the 200 kc and 17 mc crystals. The OVENS switch 
runs the PTO oven and the Crystal Oscillator deck oven.

I have heard of one or two failures of the little plug-in oven: the 
thermostat stuck ON, and overheated the thing. I n at least one case it 
damaged at least one crystal.  Maybe a switch in that line would be a good 
idea - it runs on 6.3 volts filament power. The other ovens run on the 25.2 
volt line.

Roy


- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing
13033 Downey Mill Road, Lovettsville, VA 20180
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