This is off topic but I'm unsure how to do it properly. I am trying to 'discipline' a couple of sources. I zero beat with 20 MHz WWV but can't tell the difference between fading and the beat, so I am stuck in the vicinity of 1 Hz possible error. That's 50 ppb I think.
What can I do to take the next step to bring the oscillators in closer agreement? I am not ready to go GPS or buy a rubidium standard. Bob ________________________________ From: Bob Stewart <b...@evoria.net> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Thursday, September 26, 2013 6:13 PM Subject: Re: [time-nuts] Shielding a DAC line Hi Bob, I should have mentioned that I added a new 5MHz output, and the coax ran within 1/8" of the single DAC wire going to the OCXO. I don't think anything else changed, but of course there could be some flake of something on the DAC line that I missed. I put on the RG-174 and I see that it's still locking high. I suppose it could be just that it was a long power cycle to the oscillator. Come to think of it, this thing does like to move to a new voltage sometimes when I have it off to mess with something. So, maybe it's just the oscillator being cranky. I haven't had it off for more than just a few seconds in a long time. If I weren't in test and development mode where anomalies are good, I think I'd put the old one back in. Thanks as always, Bob >________________________________ > From: Bob Camp <li...@rtty.us> >To: Discussion of precise time and frequency measurement <time-nuts@febo.com> >Sent: Thursday, September 26, 2013 7:54 PM >Subject: Re: [time-nuts] Shielding a DAC line > > >Hi > >I suspect that you have a ground offset between the OCXO's ground return and >the DAC's ground reference. The signal *should* be DC, Shielding it won't >hurt, but it really should not help much. If anything is an issue a simple >R/C filter at the OCXO pin should nuke it better than coax will. > >Bob > >On Sep 26, 2013, at 8:09 PM, Bob Stewart <b...@evoria.net> wrote: > >> I made some minor hardware changes to my GPSDO today and I see that it's >> locked to a new DAC voltage about 21mV higher. So, I was wondering about >> shielding the short run to the OCXO. I have immediately available RG-174 >> and I'm putting that in. But, should this be some sort of steel shelled >> semi-rigid coax? Maybe it's a dumb question, but I thought I'd ask. >> >> Bob - AE6RV >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > >_______________________________________________ >time-nuts mailing list -- time-nuts@febo.com >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. > > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
