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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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2nd Feb 2018, 3:02 pm | #1 |
Retired Dormant Member
Join Date: Feb 2013
Location: Québec City, Québec, Canada
Posts: 42
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Looking for a 76.0khz crystal for FM encoder project
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 |
2nd Feb 2018, 3:18 pm | #2 |
Heptode
Join Date: Dec 2014
Location: Lincoln, Lincolnshire, UK.
Posts: 583
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Re: Looking for a 76.0khz crystal for FM encoder project
Use a lower frequency and multiply up?
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2nd Feb 2018, 3:54 pm | #3 |
Retired Dormant Member
Join Date: Feb 2013
Location: Québec City, Québec, Canada
Posts: 42
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Re: Looking for a 76.0khz crystal for FM encoder project
This will need some kind of phase lock loop circuit..
Easier to divide a higher frequency ? But I checked multiples of 76khz and I did not find any value close enough to be divided to 76khz.. Thanks anyway for your reply. Still searching.. |
2nd Feb 2018, 4:12 pm | #4 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Re: Looking for a 76.0khz crystal for FM encoder project
Have you looked for 1900kHz or 3800kHz crystals?
Do you actually need a crystal? A carefully adjusted LC oscillator (perhaps on a harmonic, then divided) should be good enough. Last edited by G8HQP Dave; 2nd Feb 2018 at 4:20 pm. Reason: suggest LC |
2nd Feb 2018, 4:26 pm | #5 |
Retired Dormant Member
Join Date: Feb 2013
Location: Québec City, Québec, Canada
Posts: 42
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Re: Looking for a 76.0khz crystal for FM encoder project
I'm trying to clone part of the circuit of a Sencore SG-165.
The stereo MPX generator part. Everything in this circuit is derivated from a 76khz crystal/oscillator. Of course I could use an LC oscillator but it won't be rock solid stable as a crystal.. |
3rd Feb 2018, 12:09 pm | #6 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Re: Looking for a 76.0khz crystal for FM encoder project
Another option is a cheap DDS.
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3rd Feb 2018, 2:23 pm | #7 |
Heptode
Join Date: Mar 2009
Location: Portsmouth, Hampshire, UK.
Posts: 674
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Re: Looking for a 76.0khz crystal for FM encoder project
Maybe a 7.6MHz crystal and an PIC12F683 to generate 38kHz, inverted 38kHz and 19kHz all synchronous in one 8pin DIP. (Also has inhibit input for mono.)
I started this a couple of years ago and got as far as simulating the program (code attached) before deciding to use a Si4713 to give me an integrated solution including RDS. It would certainly replace an awful lot of circuitry on the MPX board, if you want originality then it would be simple to change the PIC to give 76kHz only and feed the output to TR202. In either case the PIC requires a 5v supply, LM78L05 from 12v supply? 7.6MHz crystals are common, they are used in a lot of the cheap low power FM transmitters (BH1415F series based)> Jim |