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" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
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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