Alan Very nice! Boy that write-up is a labor of love! Great job.
Eric -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Lux Sent: Friday, February 03, 2006 6:06 PM To: Alan Davis; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] An OCXO for the SDR-1000 At 02:29 PM 2/3/2006, Alan Davis wrote: >An OCXO for the SDR-1000 > > >In 2 days of spare time I produced a prototype 40mHz OCXO unit built on a >small perfboard that is mounted on standoffs behind the terminal block of >the SDR's chassis. All that is necessary to use the new OCXO is to go to >the Setup Menu and change the Clock Offset to 0 and the PLL Multiplier to >5. After a 5+ minute warmup, adjust the Clock offset so that the rotating >vector in the Phase Display Window slows down to a minimum -while tuned WWV. > >My OCXO equipped SDR-1000 is now within 0.05Hz of 15mHz WWV and it >doesn't deviate more than 0.5Hz under varying temperature due to long >transmissions! I no longer need to 'tweek' the VFO to compensate for my >rig drifting, what a relief! For the 1st time I can rely on the frequency >readout of my SDR-1000 - down to ONE HERTZ. That $150 OCXO has made the >SDR as stable as the $10000 Icom IC-7800. > >For complete info on my SDR-1000 OCXO project, including the stability >study and photos of the OCXO board installed, see >"http://www.n9vv.com/K2WS-OCXO.html"; . > >73, Alan K2WS Excellent writeup on your webpage. You make some great points about not necessarily needing "atomic clock" precision. For others looking to do this, Bliley is one source of OCXOs, Vectron, Frequency Electronics, and Wenzel are some others. I bought some 10 MHz Wenzel OCXOs last year (Premium Streamline SC for $249), but Wenzel also has other frequencies, and the costs should be comparable. 5ppb frequency accuracy over 0-50C, aging is 1E-10/dy after 30 days. (Wenzel part # 501-04609a) You can save 20 bucks if you go with the lower performance "non-premium" which has 15ppb frequency accuracy and 1E-9 aging. You can also find inexpensive high quality 10 MHz HP OCXOs(i.e. 10544) on eBay, etc., but the accuracy, stability, aging, and phase noise will depend on the exact model: Some instruments need good absolute accuracy, at the expense of phase noise (e.g. a counter), others need good phase noise, but can tolerate more error (e.g. a spectrum analyzer or signal generator). These seem to be in the $50 range. You might be able to scavenge one from a "broken" piece of test equipment from a hamfest, too. I bought an working HP counter with some dead nixies very cheap ($20), but it has the high stability timebase option, and I'm sure, I could extract it out of there if I needed it. There is an advantage in going higher in frequency, because the noise gets multiplied up inside the DDS. _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
