[time-nuts] Vremya-ch Hydrogen Masers

Bob Camp lists at rtty.us
Wed Mar 3 00:47:47 UTC 2010


Hi

The dielectric constant of water is also highly temperature dependent. If it's a direct dielectric thing, it should show up as a secondary temperature effect.

Bob


On Mar 2, 2010, at 6:30 PM, Joseph M Gwinn wrote:

> time-nuts-bounces at febo.com wrote on 03/02/2010 04:51:15 PM:
> 
>> From:
>> 
>> "Bob Camp" <lists at rtty.us>
>> 
>> To:
>> 
>> "'Discussion of precise time and frequency measurement'" <time-
>> nuts at febo.com>
>> 
>> Date:
>> 
>> 03/02/2010 04:55 PM
>> 
>> Subject:
>> 
>> Re: [time-nuts] Vremya-ch Hydrogen Masers
>> 
>> Sent by:
>> 
>> time-nuts-bounces at febo.com
>> 
>> Hi
>> 
>> Without doing a lot of digging, I doubt we'll find out just what they 
> did
>> (or didn't) find and fix. They certainly started with a "from scratch"
>> design. They may have multiple points of departure from the US approach.
>> 
>> Then again, it may just be a better brand of coating they spray on the
>> boards.
> 
> It does not take much moisture absorption in printed circuit boards and 
> conformal coats to cause significant variation in electrical delay with 
> variation in humidity, given that the dielectric constant of water is 
> about 80.  The solution may be no more complex than use of only 
> low-absorption materials surrounded by hermetic metal enclosures also 
> containing a cloth bag of moisture absorbing chemical granules.
> 
> Joe
> 
> 
>> Bob
>> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Magnus Danielson
>> Sent: Tuesday, March 02, 2010 3:05 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Vremya-ch Hydrogen Masers
>> 
>> Bob Camp wrote:
>>> Hi
>>> 
>>> I hear that the US ones look better than the Russian ones when you 
> have
>> them
>>> spinning around on a frozen pond. Nether one does a very good
>> triple axle
>>> jump though. At least that's what I read on the internet....
>>> 
>>> ---------------
>>> 
>>> There's always been a *lot* of debate about exactly what the source of
>>> humidity impact on the US built masers is. It's been talked 
>> about for at
>>> least 30 years. It's not real surprising if somebody 
>> somewhere has found
>> the
>>> answer and fixed it.
>> 
>> Rather, what did the Russians figure out and fixed?
>> 
>> Cheers,
>> Magnus
>> 
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>> 
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