Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
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My Hobby Website:
Crystal Reference Oscillator Design - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: Crystal Reference Oscillator Design.
Posted: Sun Oct 21, 2007 3:25 am
Tue Feb 27, 2007 6:16 am
For the sake
of learning and my own interest, I have been designing a UHF data radio.
Is this correct ?
If my carrier freq is 450.325MHz accurate
Lets say Im using a 20MHz Crystal reference oscillator
for my PLL.
Then a rough calculation tells me that my crystal must
be accurate to within -> 20*PPM*(450.325*10^6)/(20*10^6) < 200
Where PPM is parts per million.
calculations are correct, can anyone recommend where I can find a crystal
reference ocillator with a TTL or CMOS output, accurate to 0.44PPM?
I believe an oscillator from 5MHz to 25MHz would be suitable.
FYI my channel width is 25kHz, Im using National's LMx2346. Thankyou
Regards Darcy Randall, Perth, Western Australia
Regards, Darcy Randall, Perth, Western Australia
Post subject: Posted: Sun Oct 21, 2007 5:14 am
Joined: Mon Jun 27, 2005 2:02 pm
Your calculation is correct.
For such a tough spec as you have a simple Crystal is not good enough.
You should use a TCXO. I found an example for one with 0.28PPM and
a CMOS output:
http://www.valpeyfisher.com/openlink.as ... FTX160.pdf
You can also ask for samples and define the frequeny that you
need. Please contact the manufacturer for further help.
Post subject: Posted: Sun Oct 21, 2007
Joined: Tue Feb 27, 2007 6:16 am
Darcy Randall, Perth, Western Australia