[ARC5] WHINK and crystals.

[J. Forster]

The guy used a mirror, probably because it was a cheap 'optical flat'.
Ande distortions are readily noticeable. Today, with 'float glass'
probably any glass plate from a hardware store will work...  thye thicker
the better.

As to grinding medium, fine gvrinding powder for amateur telescope makers
is worth a try. It comes is a wide variety of grits, from gravel to rouge.

-John

================




> Gentlemen,
>
> For whatever it may be worth, I had occasion to observe a fellow radio
> amateur and CAP communications person who regularly ground crystals.  I
> recall that he would accumulate a large number of FT-243 crystals of
> varying frequency and put them on the CAP frequency of 4585 kHz.  He did
> a combination of lapping and etching.  I recall that he used a
> heavy-duty mirror surface for lapping.  The one thing I also recall was
> that, for periodic testing, he used two electrodes (sic) from an FT-243
> holder with leads attached and held the thing together with a stout
> wooden close-pin. This was wired into an oscillator which, in turn was
> hetrodyned with a BC-221 into a receiver (Remember, this was in probably
> 1959).  Apparently, the pressure was what was need to emulate the
> pressure the holder would provide.  He made crystals for CAP for
> probably 20-plus years with very good success.  I recall the "figure-8"
> pattern he'd use to lap/grind the crystals.  I do not know the chemicals
> nor compounds he used, but suspect it what you all mention, here.  I may
> give it a try as I have some crystals near 3885 that are within
> reasonable distance down the band.  We'll see!
>
> Jeep K3HVG
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