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Looking for a 76.0khz crystal for FM encoder project

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arcenson

New Member
Does anybody know where I could buy a 76khz crystal (or oscillator) ?
I already found 76.8khz values but I need a 76.0khz.
This will be used for a FM MPX encoder project.
This 76khz will be divided by two to generate 2 x 38khz
180deg out of phase signals..
Some 38khz crystals are available but still I need a 76khz.
Any new old stock distributors ??
Thanks
J-Pierre
 

schmitt trigger

Well-Known Member
Crystal and resonator frequencies which were ubiquitous 25 years ago, when most communications were still analog, have become mostly obsolete now.

Back in those days, one would find 3.5795 Mhz (chroma) crystals used everywhere. Although still available, their usage is rapidly declining...it would not surprise me if they become obsolete in the near future.

If you can still find 38Khz crystals use a PLL with a flip-flop on its feedback, to multiply the frequency by 2.
 

MikeMl

Well-Known Member
Most Helpful Member
...
If you can still find 38Khz crystals use a PLL with a flip-flop on its feedback, to multiply the frequency by 2.
Or use a doubler whose output is tuned to 2X, then use a Schmitt gate to square it, and use that to tickle a flip-flop
 

ronsimpson

Well-Known Member
Most Helpful Member
This will be used for a FM MPX encoder project.
When I did broadcast, the radio station sent a 19khz pilot tone that we PLL up to 38khz. I think you need to use the 19khz/38khz that is in the FM MPX signal.
edited:
I think having the same frequency will not be good enough. I think you need to be in phase with the signal from the MPX.
Your 38khz and the 38khz (from the source) must be in phase to with in 10 degrees or you will not like the sound. If you could find a 38,000.000hz crystal the MPX signal will not match your 38khz. I think you will not be able to decode stereo.
 
Last edited:

Ramussons

Active Member
You can try to "pull" down the frequency of the Xtal by adding a small capacitor ~5 -10 pf across it. The variation would depend upon the inherent internal capacitance of the Xtal.
 
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