[ARC5] Wartime FT-243 xtal mfrs

[hwhall@aol.com]

Resurrecting an old thread.  But I'm fascinated by crystals. Lemme grab some popcorn! I think AF4K's old website had a list (incomplete) of manufacturers.

 https://af4k-crystals.com/RadioCrystals-Holders-Companies-History.htm#companies

Wayne
WB4OGM

On Friday, April 3, 2026 at 05:11:52 PM MDT, Richard Knoppow via ARC5 <arc5 at mailman.qth.net> wrote: 

    I don't know if there is a list of companies but there is certainly 
a lot of historical material out there. Making good crystals was black 
magic until it was discovered that synthetic crystals could be made. 
Most crystal material came from Brazil and was difficult to get during 
war time. A great many crystals turned out to be defective. It was then 
discovered the bad ones could be crushed up and new, synthetic crystals 
grown, which were nearly perfect. Other discoveries were etching and 
plating. At the beginning of WW-2 making crystals was a sort of 
specialized cottage industry. There had been a relatively small market, 
which exploded with the requirements of the war.
    Let me see what is in my files and if I can find on-line sources.
    It is an interesting subject, somewhat akin to the discovery of how 
to make optical glass (mostly by Bausch & Lomb)  and how to coat lenses.

On 7/30/2023 6:28 PM, Paul Thekan wrote:
> I recently obtained a box of close to 800 or more FT 243 xtals ,haven't 
> counted them all yet, and was going through them looking for any useful 
> freqs on the ham bands and noticed how many different companies were 
> making xtals during the war. So far I've identified at least 45 
> companies making these xtals.
>   Is there any info out there that talks about how many companies were 
> involved in making these xtals.
> Thanks
> Paul
> N6FEG
> 
> 
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-- 
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

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