Some notes on the World War II supply and demand for quartz crystals for precise radio frequency control, in preparation for reading "Crystal clear : the struggle for reliable communications technology in World War II" by Richard J. Thompson, Jr. (Wiley, 2007). I have the book on its way on inter-library loan from MeL, via the Ann Arbor District Library.
The table of contents from the book:
Introduction : "We were heavily armed, and we had crystals" -- From wire to wireless : the development-- and acceptance-- of tactical radio -- Crystal control-- the great gamble -- The Signal Corps lays the foundation -- Nothing else to do but grind crystals -- Riding the "Flat Wheel Limited"-- overseeing a mass production industry -- Supplying a mass production industry-- the civilian government steps in -- "The whole radio crystal program of the Armed Services depends upon the success of the procurement program in Brazil. Nothing must be allowed to interfere with it" -- "God made lots of small crystals" -- The aging crisis-- stopgap measures -- The aging crisis-- physics to the rescue! -- "Without crystals, you have radio; with them, communications" -- Appendix 1 : Crystal-controlled equipment -- Appendix 2 : Crystal manufacturers.
The US Army's history of the Signal Corps is told in "The Signal Corps: The Outcome". Chapter 3, "The Signal Corps in the ETO to Mid-1944", has this to say about the use and preparation of the crystals themselves at p.89:
Over the strenuous objection of General Vulliamy and the signal staff, the committee took frequencies from the ground forces and reduced the already narrow separation of channels in the 1- to 5-megacycle band from five kilocycles to four. That meant grinding more crystals, and on extremely short notice, for it was 10 May when the revised frequency allocation list was issued. But in this specialty the Signal Corps had become proficient, even to the point where what had once been a most exacting laboratory technique was now transported into the field, and mobile crystal grinding teams were at hand. The task of providing crystals by the thousands, meticulously prepared, emphasized the one drawback to their use. Nevertheless, the American decision to use crystal-controlled mobile FM radio greatly simplified the job of frequency control in the jam-packed spectrum of sky over Europe from D-day on.
Where did these crystals come from? Before the era of lab-grown quartz, the predominant supplier of suitable quartz crystals comes from a few large quartz mines in Brazil. A 1943 US Information Agency short, "Brazilian Quartz Goes To War", is available from an exhibit at the University of Indiana.
The value of Brazilian quartz to the allied war effort is shown as narration proclaims "two-way radio is the one really new instrument in the armory of warfare." Explains the value of quartz in radio communication, showing how a wafer of its crystal makes possible the simultaneous broadcasting of many stations without overlapping. The film emphasizes the necessity for international cooperation in the war effort.
After the war, the supply of war surplus crystals entered the ham radio market. Dennis Monticelli, a Fellow at National Semiconductor, tells the story in an article in EDN.
During WWII crystal making took a leap forward in the US and turned into a big cottage industry supplying the wartime needs. There is a wonderful new book out on that subject that goes through the history and basically makes a “how we won the war” claim. Following the end of hostilities, the cottage industry collapsed and huge numbers of used and NOS crystals in screwed together non-hermetic holders flooded the market. Hams began grinding again and didn’t have to move the freq as much as before because the selection of starting material was huge. Hams could then use mild abrasives like comet or even milder like toothpaste powder. Today you could use wet silicon carbide sandpaper if you wished. I actually succeeded at etching them to freq using a very dilute HF solution when I was 15 and didn’t know how dangerous HF acid was.
You will still hear radio amateurs who talk too long on a local 2 meter repeater to the point that the repeater times out refer to this as winning the "purple crystal award". I wasn't able to pin down any origin story for this phrase, or even to know if this is a regional Michigan thing or in common global use.
A few bits of additional information:
IEEE TV: Richard J. Thompson. A 9 minute 2007 interview with Richard J. Thompson, author of "Crystal Clear".
A brief history of quartz crystals and their aging problem, Planet Analog. A 2021 discussion of how quartz crystals fail and drift due to aging from cracks and microparticles, a problem solved by smoothing the surface with acid etching.
Crystals Go To War, US Army Signal Corps, digitized by Reeves Sound Laboratories for the Prelinger Collection at the Internet Archive. 1943. "A story in pictures of the preparation and manufacture of quartz crystals for radio communication."
Thanks to Jacek KW4EP.
Quartz Crystal Growing, Western Electric / Bell Telephone Labs / AT&T Archives, 1962. A video showing postwar innovation in synthetic crystal growing technology, using a high temperature, high pressure vessel to dissolve and then redeposit quartz onto precision cut seed plates for crystal growth.
UFFC-S History, IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society. The "frequency control" portion of this professional society's archives include records from the 1944 Crystal Conferences. "This period was one of considerable growth, both in the quantity of crystal units produced and in advancing the art in crystal theory, design, and manufacturing. There were approximately 15 companies before the war who were making, at most, 100,000 crystals per year. During the war, this number grew to about 115 companies and 30 million crystals per year."