[time-nuts] Grinding crystals...

[Bob Camp]

Hi

Crystal processing is typically monitored either by time or by frequency shift. Grind in this lap powder for xxxx frequency change. Etch in xxxxx stuff for 30 seconds. Different factories do it different ways. The ones that I am familiar with seem to mostly monitor by frequency change. 

Bob

On Jun 20, 2013, at 7:57 PM, Gary <nuts at lazygranch.com> wrote:

> 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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