On Fri, 10 Oct 2003 09:47:26 +0100, "Airy R. Bean"
wrote:

I wish to make a master oscillator for the shack, and am considering
cutting my own crystals in order to reduce ageing. Is there a source
of raw material?

Also, for temperature compensation, I am considering the use of bi-metals.
(I've never seen one, but what is the mechanism used in Oxley's
Tempatrimmer?)

My dear Airy, I am so pleased to hear of your proposed project. The
'Raw Material' is readily available here in Cornwall, its called
Quartz, and is free for those willing to collect it. However if you
send me a large SAE I'll send you a few tons. HI

I'll assume the question is a genuine one about the Oxley trimmers
so...
AFIR it was two variables in one encapsulation, one with a positive
temp coeficient and the other negative. when you varied the trimmer it
added one coeficient and reduced the other, without changing the
capacitance.. At least thats the way it was explained to me many years
ago. I hav'nt seen one for years except in my junk box, and come to
think of it I hav'nt seen those for a while.

hth Mike W