[time-nuts] Grinding crystals...
Gary
nuts at lazygranch.com
Thu Jun 20 19:57:30 EDT 2013
A common scheme in metal deposition measurement is to measure the frequency of a crystal prior to starting the deposition process, then monitoring the frequency shift of the crystal as the metal is sputtered.
I was told crystals are tuned this way at the factory, but don't know this for a fact.
"Burt I. Weiner" <biwa at att.net> wrote:
>Brian,
>
>I remember grinding FT-243 crystals. I had a TV set safety glass
>about 18" square and about 1/4" thick. That and some Comet type
>cleanser mixed with water to make a thin paste would work wonders. I
>was taught to put my finger on the corners and grind an equal amount
>on the 8 corners (4 on each side) so as not to remove the bevel of
>the quartz. Once I applied this lesson I was able to grind crystals
>that were more stable and more active. When I over-leaded them I was
>generally able to remove the lead using alcohol. I've still got the
>old TV safety glass although it has an area near one corner that is
>very opaque do to all the grinding that was done in that area. Those
>were fun days!
>
>Burt, K6OQK
>
>
>>From: Brian Alsop <alsopb at nc.rr.com>
>>
>>Reminds me of the FT-243 xtal controlled transmitter Novice days.
>Xtals
>>of the frequency you wanted were hard to come by. We would grind
>xtals
>>a bit on a bed of very fine abrasive to raise their frequency.
>>
>>The other trick was taking a pencil and adding graphite to the xtal
>>faces to lower it's frequency. You couldn't add too much or it would
>>stop oscillating-- forever. Never did understand the forever part.
>>Removing the graphite didn't bring it back to life.
>>
>>Brian
>>K3KO
>
>Burt I. Weiner Associates
>Broadcast Technical Services
>Glendale, California U.S.A.
>biwa at att.net
>www.biwa.cc
>K6OQK
>
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