[ARC5] Wartime FT-243 xtal mfrs

[Tom Lee]

As did Al Klase a couple of years ago, I strongly recommend "Crystal 
Clear": 
https://www.amazon.com/Crystal-Clear-Struggle-Communications-Technology/dp/1118104641

It mentions many of the pioneering companies and is a great read overall.

-- Tom

On 4/3/2026 4:11 PM, Richard Knoppow via ARC5 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.