[time-nuts] Bye-Bye Crystals

jimlux jimlux at earthlink.net
Mon Mar 13 19:11:27 EDT 2017

On 3/13/17 2:59 PM, Alan Melia wrote:
> .....and some micro-soldering kit to attach the plated unit to the lead
> frame. Our factory used homemade hot air jets, I have no idea what the
> solder was prob LMP.
> Lapping a single blank is difficult, one tends to get rounded edges(even
> with the best machine) which affect the activity. See the video, they
> are lapping several at the same time. The unplated blanks are put into a
> skelton holder and measured and the most promising one proceded with.
> First an evaporated contact to fix the blank to the lead frame. Then
> electrode evaporation which brings the frequency down, so the final
> stage evaporates electrode while measuring the mounted crystal
> frequency. Allowances need to be made for the can.
> I doubt most small modern firms would have a X-ray goniometer (?) The
> one I saw in the 60s would never pass H&S criteria now. They probably
> buy cut blanks in bulk, I think they are relatively cheap this way. My
> supplier in the 90s did this.
> The whole job is quite labour intensive, making a single crystal might
> easily eat $1000 worth of manhours for an amateur, not even allowing for
> the occasional "oops".
> :-))

But you would wind up with some nice "artisanally hand crafted" crystals 
to plug into a retro radio.
Definitely good for one-upsmanship at the local craft brewery.

I put this in the same sort of bucket as grinding your own telescope 
mirrors - maybe something to try once.

Not all crystals are plated, either. I recall pulling crystals out of 
holders and using toothpaste to raise their frequency, and a pencil to 
lower it. (I will not claim high quality or stability or anything good 
about it).

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