HI Tom, I realised when I read your reply that I had not said how I was observing the result. I am feeding these signals into a 100 MHZ CRO not a counter and visually observing the 2 signals in relationship to each other. 1 being the Trimble which I believe to be good to 3 parts in10^12 and the Sulser up in the 10^11 range..Have a couple of HP5245L counters but I have not arranged an external reference for them yet. I hope that clears up what I am doing. Regards, Don VK3YV....
----- Original Message ----- From: "Tom Van Baak" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Saturday, March 03, 2007 1:40 PM Subject: Re: [time-nuts] Setting Osc Frequencies >> HI All , first time request. I wish to know how I can accurately set some >> oscillators on frequency. I have 3 Sulzer oscillators .. 1 x 2.5A and 2 x >> 2.5C's and 1 matching P/S with dead nicads. > >> My main reference is a Trimble Thunderbird which was the second source >> to >> the HP unit was used in cellular phone installations in the US a while >> ago I >> think that they maybe Nortel pulls like the HP's that were around. > >> I have tried in the past by putting the main reference into input "A" and >> triggering 1 cycle of 10 MHZ and feeding one of the other oscillators >> into >> input "B" and adjusting the Sulzer to be totally overlaid with no >> movement >> over many hours.. All Sulzers had been on for 36 hours before the >> test.and >> the Trimble has been on for 2 years. > >> What accuracy can I expect from this method, and is there a better method >> with the equipment I have. >> Regards, Don VK3YV....... > > It would depend on the specs of the time interval or frequency > counter you're using. You mention, 1 cycle of 10 MHz; that's > 100 ns. And you mention "many hours". The upper limit based > on that alone is 100 ns over, say, 10 000 seconds which gives > you a resolution of 1e-7 / 1e4 seconds = 1 part in 10 to the 11th. > > That's than enough accuracy, since, during that couple of > hours a 36-hour warmed-up Sulzer will likely have drifted in > frequency by about that amount. > > /tvb > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts