[Boatanchors] Crystal Holder Pressure

[Bry Carling]

It;s interesting. I have been dissecting various crystals for many years.
Especially the FT243 ones.

You woul dbe amazed at HOW many different internal designs there are!
The SPRINGS have a HUGE variety.  Th epressures must be ALL over the map. Not only from the spring but MANY other factors. That being said. You can move a blank from one crystaol holder to another without much change in frequency with spring pressure etc.

What seems to have REALLY put the whammy on older crystals was to put a SCREW through the front of the top plate and start stressing the quartz crystal with it. This was a technique used by Bliley and others who would commercially supply these monstrosities to hams so they could VXO their quartz crystals I understand that this owuld quite often bring a very sad look to Junior's face whenever he would try to VXO "Too Far" in the hopes of working that "Rare One!!" Of course some guys made their own too, by drilling and tapping a hole. Not as fancy looking as the commercial ones in appearance. Probably equally disastrous results for many(!)

73 & HNY - Bry AF4K


________________________________
From: boatanchors-bounces at mailman.qth.net <boatanchors-bounces at mailman.qth.net> on behalf of Gary Peterson <kzerocx at rap.midco.net>
Sent: Tuesday, January 1, 2019 7:29
To: boatanchors at mailman.qth.net
Subject: [Boatanchors] Crystal Holder Pressure

Absent any other information, I would be inclined to measure the frequency of a crystal blank in its original holder.
Then, remove this same blank from its holder and place it in your open, horizontal holder.  Next, add known amounts of weight,
until the frequency measures very nearly the same.

If you want the modified crystal to be very accurate, you may have to go back and forth between etching and measuring
the blank in its real holder with the associated transmitter.

Gary
K-zero-CX


“Does anyone have an idea how much
weight should press-down on the crystal blank to
correctly simulate the holder?
Dave AB5S”
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