EB4APL escribió: > David Blaschke wrote: > >> I used the SDR-1000 exclusively during the EME contest. I found one >> troubling fault: Often after restarting the radio, I would set the >> frequency to 144.129, only to find that it was really transmitting on >> 144.141. I had to restart the radio to clear this problem. It is >> unpredictable when this will happen, but if I get the radio started >> and it is finally transmitting on the shown frequency, it will stay >> there for the duration. >> >> This happens with both Version. 1.6.2 and 1.6.3. >> >> I have now made a habit, now to take the frequency counter and place >> it near the amplifier to assure that I am on the correct frequency >> whenever I have restarted the radio. >> >> If anyone has any ideas on this problem, and its fix - please email >> me directly also as well as this reflector. >> >> >> Dave, W5UN >> Home Page: http://web.wt.net/~w5un/ >> >> > Dave, > I used to have a persistent frequency accuracy issue on my SDR 1000. It > started on (at least) two distinct frequency offsets. After > realizing what the problem was (but not the failure mechanism), I used > on each power on first to tune to a MW broadcast station: if it was off > frequency, I cycled power off and on until the carrier appeared where it > should be. > It was not drift, just a percentual jump in frequency. Also I noticed > sudden phase jumps when receiving wefax stations without any reasonable > explanation for it. > Since it pointed to a problem in the oscillator and I had not any > suitable means of checking its stabulity, I temporarly replaced it by a > recycled 50 Mhz computer clock module and adjusted the DDS multiplier > acordingly. > This confirmed the oscillator as the cause of the problem. I replaced > it (50 bucks) and both problems are gone. > I think mine is not the only faulty oscillator found, and maybe this is > not your case. > > Hi, I have found a table with some measurements I made when I was troubleshooting this issue. Since the cause of the frequency jump is unknow to me it cannot be applied to other failures, but it can ilustrate the symptoms.
/VFO Real freq. Ratio 0.585 0.582939 1.0035355328773679578823856355468 5.9 5.879044 1.0035645251166686284368683071601 7.115 7.089728 1.0035645937333562020997138395154 10.0 9.96447 1.0035656688213221576260453390898 19.99991 19.928763 1.00357016639718180200145889637 Since the ratio is constant, disregarding the measurement errors, it looks like the oscillator sometimes starts on 199.2885 instead of 200.0 Mhz, who knows why. / Yes, the cause was the oscillator. 73 de Ignacio, EB4APL -------------- next part -------------- An HTML attachment was scrubbed... URL: /pipermail/flexradio_flex-radio.biz/attachments/20061116/ec5665f4/attachment.html _______________________________________________ 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 Homepage: http://www.flex-radio.com
