Formulas & Data:
- Electronics
- Mathematics
- Physics
- RF & Microwaves

Parts Vendors:
- all hand-selected

- Amateur Radio
- Vintage Articles:
- Electronics World
- Popular Electronics
- QST
- Radio & TV News
- Radio Craft
- Short Wave Craft
- Wireless World

- Events Calendar
RF Cafe Homepage
Copyright 1999-2015   •−•  ••−•    −•−•  •−  ••−•  •   "RF Cafe" in Morse Code  >> Listen to It <<
- EW & Radar Handbook
- Quizzes       - Software
- App Notes
- Calculators
- Advertise on RF Cafe
- About RF Cafe™
- RF Cafe Shirts & Mugs
- RF Cafe Archives
RF Cafe Book Contest
- RF Cafe on Visit RF Cafe on Facebook Visit RF Cafe on Twitter Visit RF Cafe on LinkedIn
- Tech Humor
- Forums Archive
- Job Board
- Donate to RF Cafe
- Kirt's Cogitations
Custom Search
More than 10,000 searchable pages indexed.
Greetings: There is so much good stuff on RF Cafe that there is no way to list or link to all of it here. Please use the Search box or the Site Map to find what you want - there is a good chance I have it. Thanks!

Crystal Reference Oscillator Design - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


darcyrandall2004
Post subject: Crystal Reference Oscillator Design. Posted: Sun Oct 21, 2007 3:25 am

Colonel


Joined: Tue Feb 27, 2007 6:16 am
Posts: 46
Hello,

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 to +/-200Hz
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 -> 0.44PPM.
Where PPM is parts per million.

If these 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


Top

IR
Post subject: Posted: Sun Oct 21, 2007 5:14 am

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello Darcy,

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.


Top

darcyrandall2004
Post subject: Posted: Sun Oct 21, 2007 9:03 pm

Colonel


Joined: Tue Feb 27, 2007 6:16 am
Posts: 46
Legend. Thankyou

_________________
Regards, Darcy Randall, Perth, Western Australia







Posted  11/12/2012

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger… single-handedly redefining what an engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5th MOB: My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website