Hi The only practical way to set the 10811 or 10544 is with a >= 10 turn pot on the EFC. I never have worked out just why there are so many instruments that don’t have a pot on the EFC.
Bob > On Nov 4, 2016, at 11:35 AM, Peter Reilley <[email protected]> wrote: > > I gave up on trying to use the GPS 1 PPS signal to calibrate the 10 MHz > OCXO's that > I have. The reason that others have pointed out is that the uncorrected 1 > PPS > signal from the GPS is has just a little too much a jitter to use it for > calibration > with your eye using a scope. If it were sawtooth corrected then it would be > better > but you really need a GPS disciplined oscillator. > > Not to be outdone, I brought out a rubidium oscillator that I had put away > because > it did not appear to work properly. It only put out a 1 PPS signal and > nothing else. > I compared that with the GPS PPS and could get a good comparison on the scope. > The rubidium drifted about 40 nS over 12 hours. So it seemed to be good. > > With that I could adjust the OCXO's in my 5370's. The spec for the HP 5370B > with > a HP 10811 OCXO is better than 1 X 10^-10 RMS for 1 sec average. That is, it > should > take more than 1,000 seconds for one 10 MHz wave to shift by 360 degrees. > That > is very hard to do using the screw adjustment in the OCXO. Even the > slightest > movement possible will cause a frequency change greater that is spec'ed. How > do cal labs do it? > > My HP 5370A has a 10544 OCXO which is spec'ed for short term stability of > better than 1 X 10^11 for 1 second. Even better than the 5370B! The > adjustment > screw is much coarser and it is not possible to get any better than a few > seconds for > one cycle phase shift of the 10 MHz OCXO against the standard. It seems > that I can't > get even close to the spec. > > These have been running for a few days. It that enough? > > Pete. > > > > On 11/3/2016 8:20 AM, Peter Reilley wrote: >> I am the proverbial man with too many clocks and I don't know what time it >> is. >> To correct this situation I have decided to calibrate everything. >> >> I have a HP 5370B, a HP 6370A, and a HP 5328A all with the TCXO option. I >> also >> have some TCXO modules. I figured that I would calibrate them against my >> Trimble >> Resolution T GPS receiver. >> >> I put the 1 PPS signal in one channel of my scope and one of the 10 MHz TCXO >> signals in the other channel and look at the phase relationship. The TCXO's >> are >> already close enough that I should not be out by more than a fraction of a >> waveform. >> I understand that I have to deal with the 1 PPS without sawtooth correction. >> >> I expected to see the 10 MHz signal bounce around but not move more than 1/2 >> of a wave length. Instead I see the 10 MHz waveform appear steady for a >> few seconds >> then jump a significant portion of the wave. The jump is too much to be >> confident >> that I have not slipped one cycle. >> >> Can I do what I am trying to do or am I missing something? >> >> Pete. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
