HI What frequency is the crystal and what sized package is it in?
Bob > On Feb 14, 2017, at 11:20 AM, Scott Stobbe <scott.j.sto...@gmail.com> wrote: > > Taking a second look in the manual, they specifically call out that its not > an AT or BT, so I'm not sure what it would be. > > Interestingly they describe the thermometer as space-saving and trouble > free alternative to a heater and thermostat apparatus (I guess they weren't > called ovens yet?) > > On Mon, Feb 13, 2017 at 10:11 PM, Bob Camp <kb...@n1k.org> wrote: > >> Hi >> >> >>> On Feb 13, 2017, at 8:15 PM, Scott Stobbe <scott.j.sto...@gmail.com> >> wrote: >>> >>> On Mon, Feb 13, 2017 at 6:41 PM, Bob Camp <kb...@n1k.org> wrote: >>> >>>> >>>> >>>> I think what you would find is that it *is* a fairly normal AT cut and >> the >>>> data book >>>> that came with the instrument plotted out the data for the specific >>>> crystal in >>>> the device. The usable temperature range was fairly small, so the plot >> will >>>> be pretty linear. >>>> >>> >>> Attached is a plot of crystal calibrators temperature stability. Span is >>> roughly 65 degC. >> >> Which eyeballs out to be pretty close to an AT. Without knowing the PPM >> scale there isn’t much way to be sure. >> >>> >>> One of the other aspects I think is intriguing is the DC PSRR of a vacuum >>> tube crystal oscillator. In the case of a bjt based oscillator you have >> the >>> C-V relation for depletion capacitance and the base-emitter dynamic >>> capacitance as a function of collector current. I would suspect that for >> a >>> one active device oscillator, tube vs bjt, a tube crystal oscillator >> would >>> be less sensitive to small power supply variations (+- 10% ). >> >> Except you *do* have miller effect which pretty much messes things up >> for a triode. A pentode is a bit less sensitive, but you still have issues. >> >>> Which is a >>> convenient attribute for a poorly/unregulated battery supply in the >> vacuum >>> tube case. Unless filament current has an appreciable impact on >> frequency, >>> I wouldn't think so… >> >> Umm… errrr …. check it out :) >> Oddly enough, I remember a high school physics lab where they had us plot >> the effect of filament voltage on plate current and gain. Seemed like a >> weird >> thing to do to me at the time. Turns out the teacher grew up with >> microwave tubes >> that were tuned by varying the filament. Who knew ??? Pretty strange >> stuff if >> you ask me. >> >> The bigger issue is the tubes get hot. The heat varies with supply voltage. >> Temperature change is the result. That temperature change messes up >> oscillator stability. You pretty much have to wait for things to hit >> equilibrium >> before you do useful stuff ( = let it warm up for an hour or four). >> >> Bob >> >> >> >>> <Lampkin105_CrystalTempCo.png>______________________________ >> _________________ >>> 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. >> > <Lampkin105_CrystalText.png>_______________________________________________ > 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.
