At 02:06 PM 5/28/2007, Bob Maser wrote: >Mine started in the -150 range and 6 months later, is -2680 and continuing >lower. Maybe this is Flex's way to make money in the after market selling >replacement crystal oscillators.
Surely you jest. Actually, the beauty of the SDR1000 is that you don't much care what the frequency is, because aging can be compensated in software (as you've noted). All crystal oscillators have tradeoffs among aging, spectral purity, and temperature stability. The ability to compensate the change in software means you can spec an oscillator with outstanding spectral purity (low phase noise), and not have to pay an arm and a leg to try and solve it in hardware (ovens, careful selection of capacitor tempcos, etc.) >You can always buy a Bliley OCXO for $400. You can do it for less money ($200-250 for a Streamline OCXO from Wenzel, for instance, $50 for used HP10811s, less if you pull them out of dead test equipment), but even that OCXO has a trimmer adjust to compensate for aging. On modern test equipment, that's probably one of the few adjustments that needs to get made (and, for modern equipment, it's a software adjustment, just like the SDR1000)) Heck, you can build your own little oven for the Vectron part on the SDR1000 board (that's essentially what the "thermistor mod" is). Part of the expense, though, is that the mfr has already run the crystal for a while to get past the "really steep" part of the aging curve, and that costs money. Essentially, you're buying an oscillator that already has 1000 or more hours on it. >Bob W6TR >----- Original Message ----- >From: "Frank Mayer" <[EMAIL PROTECTED]> >To: <flexradio@flex-radio.biz> >Sent: Monday, May 28, 2007 4:45 PM >Subject: [Flexradio] Frequency Calibration > > > >I have had my SDR-1000 since December. When I first got the clock offset > >was set to about +100 for accurate calibration. Since then it has been > >steadily needed to be reset to a lower value. It is at -1300 now. Could > >the problem be the crystal going bad? > > Frank WA3JBT. Jim,W6RMK _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
