[ARC5] WHINK and crystals.

[J. Forster]

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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