So laying a sock over the insulated oven can doesn't count? Its a thick sock. Still not at the stage of needing a chamber I am 45 Hz off.
On Fri, Jul 26, 2013 at 2:36 PM, Bob Camp <[email protected]> wrote: > 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 <[email protected]> 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 -- [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.
