[R-390] 200-kHz calibrator crystal

[Mark Huss]

Good Luck. The only source I know of is to buy the 17 Mc Oven Plug0in, 
then see if it works. I did this for my R-390A, and had an extra 17 Mc 
crystal left over. Getting crystals cut for under 1.0 MHz is very 
difficult nowdays, with the exception of 32.768 kHz. This is one of 
those places where someone may need to design a 17 MHz and 200 kHz 
oscillator that will work as a plug-in ( a 17 MHz programmable osc block 
with a divide by 85 circuit to generate 200 kHz squarewave?). How about 
using two of those Programmable Oscillators that cost about $7 each? Buy 
two surface mount ones, one for 17 MHz and the other for 2 MHz. Add a 
tank circuit for the 17 MHz one to round it off, and a divide by ten for 
the 2 MHz one. The 20 ppm ones would only be off about 350 Hz at 17 MHz, 
and off 4 hz at 200 kHz.

100 kHz crystals are more readily available. Has anyone tried to 
substitute a 100 kHz crystal for the 200 kHz one? Looking at the 
schematic, this should work as V205A should oscillate fine at 100 kHz. 
Then V206 should divide it to 50 kHz, and the tank circuit on V205B 
should give you 100 kHz markers with suppressed 50 kHz markers.

Charles A Taylor, WD4INP wrote:
> Group,
>
> I looking for a current source for the 200-kHz HC-6/U calibrator crystal.
>
> Looked that the usual crystal manufactures.
>
> Their sites don't give much information: I don't want a quote. I want a
> per-crystal price plus shipping.
>
> Thanks to all.
>
> Charles
>
> -----
> Charles A Taylor, WD4INP
> Greenville, North Carolina
>
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