Re: FT243 crystal grinding.


Leland L. Bahr
 

When grinding crystals it is imperative both planes of the crystal stay parallel. If they don't, it will not oscillate. Beveling the edges help restore activity if the blank becomes sluggish. Grinding crystals over just a few kHz is feasible in my book. I have done it. Penning a crystal works too. However I have found etching crystals allows me to go more then a couple khz. Maybe 25 khz or so before activity falls off. This idea or notion you can grind on a piece of plate glass figure 8s and move the crystal 100 khz is nonsense in my book. I have tried it too many times using different compounds. I have found it impossible to keep the two planes parallel for this far an excursion. I have talked to other hams, I respect, and have found they too came to the same conclusions as myself. A crystal manufacturer uses a lapping machine which keeps the two planes parallel. So you guys out there who have been listening to malarkey, think twice before you attempt grinding crystals yourself. There are a lot of unusable FT-243 crystals out there and there are guys re-stuffing cases, but how many guys are actually grinding a crystal to a usable frequency and then selling them? I can tell you NADA! So for the guys out there that insist this is "A piece of cake", how about grinding some for me? I'll send you the blanks and give you $5.00 each you grind for me. You pay me $1.00 each for each one you screw up. All I am saying is, I've been there, done that too many times, too many different ways to know this is a very difficult task. Maybe you will be lucky. It's been mostly a failure for me as I said beyond a couple khz bye grinding or 25 khz bye etching. However, I must say, trying to grind crystals yourself is a great learning experience.

Lee, w0vt

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