Hi Well if you get desperate to try it, I have CO2 and a chamber sitting in the garage. The biggest issue is that if we use too much CO2 for the chamber, the beer may go flat…
Bob On Jul 26, 2013, at 4:09 PM, paul swed <[email protected]> wrote: > Bob > I think the power bill exceeds the cost of a 10811. The chamber and CO2. > Going to pass.Though I am sure I can run down to work and throw a unit in > the various walk in units we have. Suspect they will not appreciate me > adjusting the temps though. > Back to work as they say. > Regards > Paul > WB8TSL > > > On Fri, Jul 26, 2013 at 3:53 PM, Bob Camp <[email protected]> wrote: > >> Hi >> >> Tossing a nice fluffy towel over it works pretty well. Just the thing if >> you are doing a bench turn hunt on an AT based OCXO. It's also a quick way >> to answer the age old question "is it broke or is it just all the people >> walking by while I'm trying to test it". >> >> You need something that will let you go say 25C 5C 25C 45C 25C. Each time >> you make a change and re-test, you want to run the same temperatures. You >> need enough air circulation (and proper ducting) so that the device OCXO >> stabilizes quickly. 300 to 600 CFM is the range most chambers run in. Dead >> air = hard to know what temperature you are at / large delta T within the >> chamber. A dwell of maybe an hour at each one is about right. A Tenny Jr is >> a pretty good chamber for home use (no CO2). Keeping the refrigeration >> repaired can be a chore though… >> >> Bob >> >> On Jul 26, 2013, at 3:33 PM, paul swed <[email protected]> wrote: >> >>> 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. >> >> _______________________________________________ >> 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.
