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Message-ID: <003601c6c4f9$56fba130$1f03210a@Hugh>
From: "Hugh_m0wye" <m0wye@radiouk.com>
To: <rsgb_lf_group@blacksheep.org>
References: <20060819.164627.3204.4.riese-k3djc@juno.com> <000f01c6c490$4b9616e0$0301a8c0@p1800>
Date: Mon, 21 Aug 2006 09:10:55 +0100
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Subject: Re: LF: TIP: modifiying X-tals
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Hi All,
I have successfully used this method to retune 27MHz radio control crystals 
to produce a couple of channel frequencies around 433.500 MHz (when 
multiplied by 16).
I used a pencil rubbed gently on the surface of the crystal.

The crystal cans were of the "solder seal" type and all you had to do was 
heat the case of the crystal with the tip of a soldering iron, and the lid 
would come off. Unfortunately modern crystal cases are welded, and I have 
not been able to get in without destrying the crystal element. (Anyone know 
any tricks here ?)

I found it quite educational, because it make you realise that a crystal 
frequency is determined by a mechanical resonance. Adding mass to the 
surface lowers the resonance.
Nice to see it happen before your eyes.

73
Hugh M0WYE


  On Sat, 19 Aug 2006 21:16:13 +0200 "Dick" <knaap159@zonnet.nl> writes:
    For those who didn't know, use following 'trick' to tune your own X-tal. 
(found it in a magazine from the VERON)

    Take an permant marker pen ("Edding, or similar) and put a little 
stripe/line on the X-tal plate.
    You will notice that the frequency goes down a bit.