[time-nuts] How quartz crystals are (were) fabricated

[Alan Melia]

Hi Charles yes I didn't actually run the video....was saving it for later 
:-))  this suggests bond disruption is being used. Like  musical string if 
you stiffen the  material the resonant frequency should drop. One can only 
guess this is what might be happening. The lab I was working in (though not 
on crystals) was producing high quality standards for BC and telecoms, and 
was part of the then Post Office Engineering Department of Research branch. 
I never heard of that method (X-rays) for trimming crystals mentioned. This 
is probably because they were not a bulk manufacturer. The more usual method 
they used was to plate for a little longer in the vacuum evaporation 
stage.....easy on one-offs :-)) the WWII 10XJ and FT243 (or was it FT241?) 
were not plated and you can only raise their frequency by lapping. The Ham 
method with soft lead pencil (or drafting ink) would not be allowed!.

Alan
----- Original Message ----- 
From: "Charles P. Steinmetz" <charles_steinmetz at lavabit.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Thursday, August 01, 2013 4:54 PM
Subject: Re: [time-nuts] How quartz crystals are (were) fabricated


> Alan wrote:
>
>>all crystals would have been subject to X-rays to some extent because this 
>>was how the planes were located and the cutting angles determined. The 
>>dose rate was probably quite low in this case
>
> Right.  The film that Alberto posted a link to also showed (beginning at 
> 35:30) a procedure that Reeves Sound Labs devised to lower the frequency 
> of a crystal after final testing, using "a powerful beam of X-rays" that 
> "alter[s] certain properties of the quartz itself."  The jig looks to have 
> quite a bit of lead shielding, although I thought they could have sealed 
> the gap around the sliding drawer somewhat better (it does appear to be a 
> redundant seal).
>
> Best regards,
>
> Charles
>
>
>
>
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