[time-nuts] backfill (was: Poor man's oven)

Bob kb8tq kb8tq at n1k.org
Thu Jun 8 22:34:07 UTC 2017


Hi

You really want to use Helium. Hydrogen is a bit reactive. 

Bob

> On Jun 8, 2017, at 5:49 PM, Alan Melia <alan.melia at btinternet.com> wrote:
> 
> Hi Bob, it also depends on what you allow to leak into the vacuum. Hydrogen is a pretty effective remover of heat :-))
> Alan
> G3NYK
> 
> ----- Original Message ----- From: "Bob kb8tq" <kb8tq at n1k.org>
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Sent: Thursday, June 08, 2017 9:19 PM
> Subject: Re: [time-nuts] backfill (was: Poor man's oven)
> 
> 
>> Hi
>> 
>> If you look at the thermal conductivity vs very low pressures, the conductivity
>> comes up pretty quickly from a hard vacuum. There is essentially no impact
>> on Q.
>> 
>> Bob
>> 
>>> On Jun 8, 2017, at 4:03 PM, Attila Kinali <attila at kinali.ch> wrote:
>>> 
>>> On Thu, 8 Jun 2017 06:55:07 -0400
>>> Bob kb8tq <kb8tq at n1k.org> wrote:
>>> 
>>>> The simple answer is that the backfill is done because it does matter in a lot of
>>>> cases.
>>> 
>>> This raises the question, why there is backfill (just for thermal conductivity?)
>>> and how much it affects the Q of the crystal.
>>> 
>>> Attila Kinali
>>> 
>>> 
>>> -- 
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