Ulrich, What are you using to produce the graph you attached please?
73, Steve 2009/6/17 Ulrich Bangert <df...@ulrich-bangert.de>: > Gents, > > yesterday I received the Z3805 that I had bought from fluke.I on eBay and > immediately put it to work. I recorded the EFC value as well as the PPS TI > value over about 20 hours. Attached is the graph of thes two values. > > I interprete this graph in this way: > > 1) Immediately after power up (perhaps up to the end of the site survey) the > regulation loop seems to work with a very short time constant which is able > to bring the PPS TI close to zero although the OCXO has lots of drift at > this time. > > 2) Then the loop time constant seems to switch to a significant higher value > which does not keep up with the oscillator's drift, which leads to the > negative excursion of nearly 500 ns. > > 3) This seems to be too much for the regulation which leads to switching > back to the short time constant and to bring the PPS TI back to near zero > and to return to the longer time constant again... > > 4) ...which lets the procedure repeat again and again: Drift to -500 ns and > pullback. > > 5) Note that I thought it was a kind of malfunction and send a > :system:preset command to the device after the last negative PPS TI spike. > The result was, that the total procedure repeated: About 2 hours of PPS TI > close to zero then again the drift and pullback procedure however with a > reduced drift rate. > > 6) After 11 hours or so the regulation loop's time constant seems to match > the OCXO's drift and a "real" lock of the pll seems to take place. (The lock > led had been on already hours ago...) > > Since I do not have an manual for the Z3805: Can any of you Z3801 owners > second this behaviour to be normal or would you think that it is kind of > special for the Z3805 or even a real malfunction (in the sense that the > OCXO's drift is above the specs in the beginning)? > > Best regards > Ulrich Bangert > > Ulrich Bangert > www.ulrich-bangert.de > Ortholzer Weg 1 > 27243 Gross Ippener > > _______________________________________________ > 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. > -- Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW A man with one clock knows what time it is; A man with two clocks is never quite sure. _______________________________________________ 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.