Whatever pretext was used to ban them, a very useful family of chemicals has been outlawed.
There was nothing like a Freon Vapor Degreaser for cleaning PCBs and other things. Essentially inert, not flamable, non-toxic, and a very good non-polar solvent... very sad. They were also very useful for HV insulation in things like TWT amplifiers and other high power avionics. -John ============= > Almost John I dont think they are Greenhouse gases, though I would not be > surprised..... more certainly Ozone killers. > > Alan > > ----- Original Message ----- > From: "J. Forster" <[email protected]> > To: "Discussion of precise time and frequency measurement" > <[email protected]> > Sent: Tuesday, September 20, 2011 8:46 PM > Subject: Re: [time-nuts] Making a 10811 better > > > Likely one of the Freons (TM) or Sulphur Hexafluoride. > > Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor > pressure of some of those compounds is low at 70F, but they do have to be > sealed. > > Unfortunately, virtually all Freon useage has been banned by the EPA (they > are said to be "greenhouse gases") and the stuff in now almost unobtanium. > > -John > > =============== > > >> Long ago and far away, I recall a friend using a gas that had its >> liquid/gaseous transition near room temperature and was inert (not an >> inert gas) to pressurize a vessel having high impedance circuits in it. >> I'm darned if I can remember what it was. Available in so-called "lab >> bottles" ie not monster cylinders. >> Would have to be sealed, though. >> Don >> >> Tijd Dingen >>> Yeah, I was wondering about that. There's a reason they use helium to >>> search for leaks on vacuum chambers. Those pesky small atoms go >>> everywhere... >>> >>> >>> >>> ________________________________ >>> From: J. Forster <[email protected]> >>> To: Discussion of precise time and frequency measurement >>> <[email protected]>@qkmail9.01trend.com >>> Sent: Tuesday, September 20, 2011 9:00 PM >>> Subject: Re: [time-nuts] Making a 10811 better >>> >>> Helium in contact with Dewar walls is a very bad idea. He diffuses >>> through >>> many glasses and will completely destroy the vacuum in a Dewar in >>> hours. >>> >>> -John >>> >>> ================= >>> >>> >>>> Depends what you mean by "much higher". Helium has almost 6 times >>>> higher >>>> thermal conductivity. Hydrogen is higher, but has certain drawbacks. >>>> ;-) >>>> >>>> regards, >>>> Fred >>>> >>>> >>>> >>>> ________________________________ >>>> From: Dick Moore <[email protected]> >>>> To: [email protected] >>>> Sent: Tuesday, September 20, 2011 8:39 PM >>>> Subject: Re: [time-nuts] Making a 10811 better >>>> >>>> Is there a relatively inert gas that has much higher thermal >>>> conductivity >>>> than air? Then a flask makes sense and is not the size of the >>>> basement... >>>> >>>> Dick Moore >>>> >>>> >>>> On Sep 20, 2011, at 5:00 AM, [email protected] wrote: >>>> >>>>> ------------------------------ >>>>> >>>>> Message: 2 >>>>> Date: Mon, 19 Sep 2011 18:21:30 -0700 >>>>> From: ed breya <[email protected]> >>>>> To: [email protected] >>>>> Subject: [time-nuts] Making a HP 10811 better >>>>> Message-ID: <[email protected]> >>>>> Content-Type: text/plain; charset="us-ascii"; format=flowed >>>>> >>>>> One last thing regarding oil-filling. My previous comment was made >>>>> picturing oil inside the oscillator block only - not outside, or >>>>> between the outer parts - if there is a resistance wire heater (I >>>>> think it's heated with Qs only on the 10811) it is held together with >>>>> various tapes and adhesives that could soften or dissolve. Also, the >>>>> insulation would not insulate very well of saturated with oil, and >>>>> could possibly soften or break down somehow. I would not recommend >>>>> dunking the whole thing in a vat of oil. >>>>> >>>>> And one final, final note: If oil is somehow effectively contained in >>>>> the oscillator block, then a void (bubble) of some sort, or an >>>>> expansion facility or vent would be needed to relieve the pressure >>>>> changes during warmup. Otherwise, when started up, the expanding oil >>>>> would have to either leak out, or deform (or damage) something. This >>>>> would be equivalent to dramatically increasing barometric pressure, >>>>> and certainly effect the oscillator frequency. >>>>> >>>>> Ed >>>>> >>>>> >>>>> >>>>> >>>>> ------------------------------ >>>>> >>>>> Message: 3 >>>>> Date: Mon, 19 Sep 2011 23:20:28 -0600 (MDT) >>>>> From: "Don Latham" <[email protected]> >>>>> To: "Discussion of precise time and frequency measurement" >>>>> <[email protected]> >>>>> Subject: Re: [time-nuts] Making a HP 10811 better >>>>> Message-ID: >>>>> <[email protected]> >>>>> Content-Type: text/plain;charset=iso-8859-1 >>>>> >>>>> Ah well. Just a thought. I was thinking of simply dumping the whole >>>>> thing into a picnic jug full of baby oil :-) >>>>> Sorta scatterbrained, but I have seen mentioned on the list a >>>>> basement >>>>> sized steel block ... >>>>> Don >>>>> >>>>> ed breya >>>>>> One last thing regarding oil-filling. My previous comment was made >>>>>> picturing oil inside the oscillator block only - not outside, or >>>>>> between the outer parts - if there is a resistance wire heater (I >>>>>> think it's heated with Qs only on the 10811) it is held together >>>>>> with >>>>>> various tapes and adhesives that could soften or dissolve. Also, the >>>>>> insulation would not insulate very well of saturated with oil, and >>>>>> could possibly soften or break down somehow. I would not recommend >>>>>> dunking the whole thing in a vat of oil. >>>>>> >>>>>> And one final, final note: If oil is somehow effectively contained >>>>>> in >>>>>> the oscillator block, then a void (bubble) of some sort, or an >>>>>> expansion facility or vent would be needed to relieve the pressure >>>>>> changes during warmup. Otherwise, when started up, the expanding >>>>>> oil >>>>>> would have to either leak out, or deform (or damage) something. This >>>>>> would be equivalent to dramatically increasing barometric pressure, >>>>>> and certainly effect the oscillator frequency. >>>>>> >>>>>> Ed >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> 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] >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>> >>>>> End of time-nuts Digest, Vol 86, Issue 55 >>>>> ***************************************** >>>> >>>> >>>> _______________________________________________ >>>> 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. >>> >>> >> >> >> -- >> "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. >> >> > > > > _______________________________________________ > 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.
