Hi Doing any real adjustment on these OCXO's pretty much requires you have a temperature chamber and a pretty good standard. A GPSDO will do for the standard, the chamber is a bit harder to come by.
Bob On Jul 26, 2013, at 1:38 PM, Rick Karlquist <rich...@karlquist.com> wrote: > Ed Palmer wrote: >> Hi Paul, >> >> Did you see this page that talks about tweaking the 10811 oven controller? >> >> http://www.realhamradio.com/z3801a-turning-point.htm >> >> Ed >> > > Although this article anecdotally claims success, it overlooks > a number of important issues. First of all, a large proportion > of 10811 crystals DO NOT HAVE A TURNOVER. They merely have a > very low TC around 82 degrees. It is ALWAYS 82 degrees for these > crystals. The crystals that do, technically, have a turnover, > still have very low TC even if the oven is slightly off the turnover. > Secondly, the tempco of the electronics, specifically > the selected 2N5179 oscillator transistor, is a significant player. > The thermal gain, if properly adjusted, is around 1000 at the > crystal, but is much less at the oscillator transistor. It may > very well be the dominant factor in overall oscillator tempco. > Possibly, if you have a crystal with a turnover, you should > deliberately operate off the turnover at a point where the crystal > drift cancels the drift of the electronics. > If you want to tweak a 10811, you should also tweak the thermal > gain by custom adjustment of the heat balancing resistors for > the heater transistors. This has to be done by converting the > oscillator to mode B and then converting it back to mode C > afterwards. > > Rick Karlquist N6RK > > _______________________________________________ > 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.