[ARC5] WHINK and crystals.

Fri Jun 28 12:32:55 EDT 2013

Optical flats come in all sizes. I have a 16" one, about 3" thick, that I
got surplus years ago.

I really think a piece of plate glass, like a very small table top, will
work just fine.

I'd go to a local glass shop and ask for a piece of scrap, then pay a few
bucks to get the edges sanded unsharp.

YMMV,

-John

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

> True, though they are much smaller than your typical 8" reticule.
>
>
> On Fri, Jun 28, 2013 at 9:19 AM, J. Forster <jfor at quikus.com> wrote:
>
>> Optical flats, used w/ LASERs are probably a whole lot flatter. They are
>> often good to 1/100th of a wavelength of roughly 500 nM light, or 5 nM.
>>
>> They are pretty expensive though. Think $300 for a 1" OD, 1" thick one.
>>
>> You can sometimes be picked up cheap on eBay.
>>
>> -John
>>
>> =================
>>
>>
>>
>>
>> > Good input, Hutch.
>> >
>> > There is NOTHING flatter than a glass reticule.  We're talking
>> microns.
>> >  These are very hard to find, even here in Si valley among all the
>> surplus
>> > shops.  The reason is not just recycling, it has more to do with the
>> fact
>> > that these masks represent the IC design itself and all such
>> information
>> > is
>> > deemed highly proprietary.  Hence this stuff just does not end up in
>> the
>> > surplus channels.
>> >
>> > Dennis AE6C
>> >
>> >
>> >
>> >
>> > On Fri, Jun 28, 2013 at 8:21 AM, John Hutchins
>> > <jphutch60bj at gmail.com>wrote:
>> >
>> >> Group -
>> >>
>> >> This is good information,  is the procedures and materials and
>> process
>> >> document existing on a web page?
>> >> Can the whole process be summarized?  If so since radio sites go up
>> and
>> >> down, same as with "yahoo group participation" could this be a
>> Wikipedia
>> >> page?
>> >> On the subject of Glass:
>> >> Glass plate you say,  find if you can;  glass used in making IC chips
>> >> called a reticule;  This is very hard and thick glass, flatter than
>> the
>> >> world before Columbus!
>> >> They used be very common and were discarded all the time;  Now
>> reticule
>> >> glass is recycled, but you may still have some sources out there.
>> >> Hutch
>> >>
>> >>
>> >> On 6/28/2013 8:55 AM, J. Forster wrote:
>> >>
>> >>> 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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