There is a Excellent PDF of Crystal Clear by Richard J. Thompson.  

https://oceanofpdf.com/authors/richard-j-thompson-jr/pdf-crystal-clear-the-struggle-for-reliable-communications-technology-in-world-war-ii-download/

Complete book with List of Manufactures.

I have it loaded on my iPad.  It is 5.4 MB.  254 pages.

Verne
W6LPM


On Apr 5, 2026, at 5:19 PM, [email protected] wrote:

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Today's Topics:

  1. Re: Wartime FT-243 xtal mfrs (Mike Feher)


----------------------------------------------------------------------

Message: 1
Date: Sun, 5 Apr 2026 20:18:57 -0400
From: "Mike Feher" <[email protected]>
To: <[email protected]>, "'Doran Platt'" <[email protected]>,
"'ARC-5 Mail List'" <[email protected]>
Subject: Re: [ARC5] Wartime FT-243 xtal mfrs
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"

Scott-



I of course have a copy as he visited me in 80?s to take pictures of some of my crystal sets. I just took a look, and found one on Amazon, https://www.amazon.com/Crystal-Clear-American-Detectors-Crystals/dp/0911572961 . 73 ? Mike



Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

908-902-3831



From: [email protected] <[email protected]>
Sent: Sunday, April 5, 2026 7:06 PM
To: 'Mike Feher' <[email protected]>; 'Doran Platt' <[email protected]>; 'ARC-5 Mail List' <[email protected]>
Subject: RE: [ARC5] Wartime FT-243 xtal mfrs



I have looked for this book for years but have yet to find a copy.



Scott W7SVJ



From: [email protected] <[email protected]> On Behalf Of Mike Feher via ARC5
Sent: Friday, April 3, 2026 6:00 PM
To: 'Doran Platt' <[email protected]>; 'ARC-5 Mail List' <[email protected]>
Subject: Re: [ARC5] Wartime FT-243 xtal mfrs



Not to be confused by the same titled book by Maurice Sievers which is about Antique Crystal Radios. 73 -



Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

908-902-3831



From: [email protected] <mailto:[email protected]>  <[email protected] <mailto:[email protected]> > On Behalf Of Doran Platt via ARC5
Sent: Friday, April 3, 2026 8:20 PM
To: ARC-5 Mail List <[email protected] <mailto:[email protected]> >
Subject: Re: [ARC5] Wartime FT-243 xtal mfrs



The best historical tome for crystals is the book "Crystal Clear".  It lists over 50 wartime crystal providers.  It goes over the Brazil Connection, Leo Meyerson, and a whole lot more.  

Jeep K3HVG

On 04/03/2026 7:46 PM EDT hwhall--- via ARC5 <[email protected] <mailto:[email protected]> > wrote:





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 <[email protected] <mailto:[email protected]> > 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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