Ah. That seems right, Charles, going by the behavior. In that case, what and where is the reference for the heater servo? The ambient temperature? Not too wise a choice, but what else? So it may be that the temperature is the controlling element but it, too, is an open system? It can be open, too, just second order? This is a knotty one! Don Charles P. Steinmetz > Don wrote: > >>This is typical for an underdamped second order servo. The oscillation >>is the penalty for a shorter settling time. A critically damped system >>would not oscillate, but approach the final value smoothly in a >> slightly >>longer time. It may have been designed for a slight overshoot... > > Yes, I understand and I don't doubt that it is performing as > designed. My point was that most crystal oscillator frequency > adjustments (at least, the ones that I have seen) are open-loop > (variable capacitor or pot to a varactor diode). Finding the fine > frequency control apparently in a servo loop was a surprise. And it > cannot be a PLL or FLL, because there is only the one reference -- > the one you are adjusting. Since the startup dynamics are so similar > to the fine frequency adjustment dynamics (not to mention that the > oven loop is pretty much the only possible servo in the oscillator), > the evidence appears strong that the fine frequency adjustment is an > oven temperature adjustment. Unless there is something truly > diabolical going on inside a 9462. > > Best regards, > > Charles > > > > > > > _______________________________________________ > 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. >
-- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind." R. Bacon "If you don't know what it is, don't poke it." Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ 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.
