[R-390] 200-kHz calibrator crystal

[Bob Camp]

Hi

Be careful of the phase noise on some of the parts out there. If you  
put in a poor phase noise source for the 17 MHz oscillator you will  
significantly degrade the performance of the radio.

Your best bet probably is to grab an old cell phone TCXO and divide  
it down to 100 KHz. Mount it under the deck where you can get  
voltages to it.

Bob


On Feb 27, 2007, at 8:52 AM, Mark Huss wrote:

> 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.
>