[Milsurplus] Crystals, et al.

[hwhall at compuserve.com]

For what it's worth, AF4K has been offering batches of cut crystal blanks for finishing. Might be a good way to get one's feet wet.Re buying quartz on ebay, etc., you have to have untwinned crystal and quartz loves to make internal twins. There's lab-grown quartz bars & slabs available.  Grown for the electronics market & often sold at gem & mineral shows.  Avoids the odds of getting an unusable piece otherwise.
These two chapters are worth reading perhaps regarding FT-241 type crystal development:THE BELL SYSTEM TECHNICAL JOURNAL, VOLUME XXIII, 1944 CHAPTER VIII Principles of Mounting Quartz Plates, By R. A. SYKES [ https://archive.org/details/bstj23-2-178/page/n5 ]CHAPTER XIIIThe Mounting and Fabrication of Plated Quartz Crystal Units, By R. M. C. GREENIDGE[ https://archive.org/details/bstj23-3-234/page/n3 ]
WayneWB4OGM
-----Original Message-----
From: CL in NC via Milsurplus <milsurplus at mailman.qth.net>
To: Milsurplus <milsurplus at mailman.qth.net>
Sent: Mon, Jan 6, 2020 1:50 pm
Subject: [Milsurplus] Crystals, et al.

In this modern ham world, folks that knew, and actually did it, are dead, and if you research, you will find articles in the mid 30's in QST, and in the Handbook of that pre-WW II era that told you how to make your own radio crystals.  Projects included the building of a saw to cut the quartz, how and at what angle, even for overtone units, a start thickness to get you somewhere near your freq. of interest and grinding techniques to bring it to freq.  Brazilian quartz is still available on Epay, not too expensive, and the design for the saw is still doable if you wanted to try making your own.  In my hopes of doing exactly that, I looked at a small bandsaw with diamond blade from MicroMark, and found out it could do the job making very thin slices in quartz.  Of course the FT243 style holder would be the surest bet to succeed.  When it comes to the leads soldered to the pad on the crystal itself, not sure how that metal is attached to the quartz, maybe sprayed on molten.  I 
 bought a manual from Tucker Electronics as they were getting rid of stuff, it was for a meter I have that is used in crystal manufacture, they sent the original, not a copy.  In it, was a typewritten document from the Midland Company that had to do with crystal production on the night shift, and it details a sort of quality assurance check list about what processes were followed in making the HC6 and smaller crystals for their gear.  If you are still hoping to use an actual rock, and not a PLL chip and the Hayseehamfest circuit board, it appears Quartzslab in Britain is taking up a lot of the slack for hams needing crystals, even though their holders are limited.  I looked up the cost of one and, unless I got something wrong, it was 10.5 Brit pounds, which is about 14 bucks US ( I do think there is a minimum order though).  Even with shipping, that is a great deal considering ICM charged about $30 for a fundamental rock in an HC6 style holder, and they had a $50 minimum orde
 r.  I have seen ads from BOMAR now for crystals.  When I called them several years ago, after getting past the front desk to the order dept. explained what I needed and what it was for, the person on the other end asked me what Amateur Radio was.  When we finally sorted it all out, the price was $100 for one crystal.  That is the reason my MultiElmac Marine radio has PLL chips and a Hayseedhamfest board.  Hopefully, they have decided to do better price wise, but I have not checked with them since.

Charlie, W4MEC in NC
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