The 1944 Crystal Conferences – notes by Ken Burch
These two conference proceedings record some of the intense activity of the quartz crystal resonator industry during World War II. 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.
Much of the documentation of this period has apparently been lost. However, summaries of the history of this period can be found in:
C. Frondel, “History of the quartz oscillator-plate industry, 1941-1944”, American Mineralogist, Vol. 30, Nos. 5 and 6, May-June 1945, pp205-213.
Raymond A. Heising, “Quartz Crystals for Electrical Circuits: Their Design and Manufacture”, D. Van Nostrand Co., Inc., New York, 1946. (Reprinted by the Electronic Industries Association, Washington D.C., 1982.)
John P. Buchanan, “Handbook of Piezoelectric Crystals for Radio Equipment Designers”, WADC Technical Report 56-156, Wright Air Development Center, October 1956, AD 110448, available from the National Technical Information Service, E-mail: info@NTIS.fedworld.gov, http://www.fedworld.gov/ntis/search.htm
The Signal Corps Inspection Agency (SCIA) held a conference on 7-8 May 1944 to discuss several problems regarding quartz crystal resonators.
The Crystal Impedance (CI) meter had not yet been invented. Crystals were tested by operating them in a test oscillator. The number of crystal manufacturers had increased eight fold in just two years and many of these oscillators were “home made” by the crystal manufacturer. Thus, the correlation of these test oscillators was a major problem. Even the correlation of the test sets at the Galvin Manufacturing Company (now Motorola Inc.) and the Hallicrafters Company (no longer in business) was unacceptable.
The aging problem was widely recognized in 1942. Some manufacturers attempted to cure the problem by heating the blanks. Other manufacturers simply finished the crystal to operate at a frequency that was a few hundred cycles low and allowed them to age to a higher frequency. The activity would decline as the crystal aged, but there was little that could be done to prevent it.
Virgil Bottom explained at the May conference that the phenolic compounds used in crystal holders often caused a loading effect on the surface of the crystal which allowed the entrance of water vapor. He went on to explain how chemical etching might solve the problem.
“The Laboratories stated that in the near future all contractors would be informed that they must utilize the etching procedure in their final finishing process.” [paragraph 19]
This particular conference was a small gathering. (34 people are known to have attended) However, this important meeting included Capt. E. F. Mitchell and Virgil Bottom (Camp Coles Signal Laboratory), Dr. K. S. Van Dyke (OCSigO), and other who have contributed significantly to the quartz resonator industry.
The 11-12 July 1944 Chicago Crystal Conference was held at the Stevens Hotel in Chicago, Illinois. This gathering was held at the request of the Galvin Manufacturing Company (now Motorola Inc.) and attempted to bring together all of the radio crystal manufacturers and SICA (Signal Corps Inspection Agency).
The Allies’ D-Day invasion at Normandy had occurred one month earlier and there was now widespread anticipation that the war would soon be over. Each of the keynote speakers emphasized that the fact that the war was not yet won.
“Well as I see the problem for you fellows you must do a little postwar dreaming and thinking, but don’t let it take a minute of your active efforts away from this job. The very fact that there is this type of conference at this time, indicates the momentum of our task.”
– Paul Galvin, founder and president of the Galvin Mfg. Co. [page 11]
The Signal Corps also emphasized the ongoing critical need for crystal resonators.
“… Our decision to go into crystal controlled radios for widespread tactical use has been more than justified by the results obtained. The Army had radio before they had crystals. Now the Army has communications. That’s the difference. Crystals gave us communications.”
– Major General Roger B. Colton, U.S. Army Signal Corp [page 12]
Previously, the focus of the Signal Corps was on increasing the volume of quartz crystal resonators produced. Now that the huge quantities had been achieved, the emphasis was shifting toward improved quality.
The crystal manufacturers were frustrated with new regulations that required new holder materials and the etching of quartz blanks to final frequency to solve the major problem of crystal aging. New inspection procedures were being put in place.
The solution to the crystal aging problem had not yet been accepted by many of the crystal suppliers.
“… The experiments are so conclusive as to convince the Signal Corps that the conditions to be satisfied in its radio circuits can be achieved only by etching quartz plates to frequency. Thus the Signal Corps is out to buy not just quartz crystals but etched quartz crystals.”
– Dr. .K. S. Van Dyke, Chief Physicist, Crystal Section, Engineering & Technical Service, OCSigO.
Nearly all of the crystal holders of this time were hand assembled. Most were constructed from Bakelite or similar plastic and held together with bolts. Moisture would often find its way into these holders and contribute to the aging problem. To solve this problem the Camp Coles Signal Labs was working on two new hermetically sealed metal holders. Lt. J. J. Maguire showed a 15 minute film which demonstrated the assembly of these enclosures.[page 44] This was the beginning of the familiar HC-6/U and similar holders which were the industry standard for the next 40 years.
- The original consists of 7 pieces of paper (8″ x 10.5″) which are stapled together in the upper right hand corner.
- Pages are single sided with the date stamped on the back of the last page.
- The original consists of paper (8″ x 10.5″) which are bound together using three staples along the left edge.
- Page 53 is blank because the original is blank.
- Pages are double sided.
- The covers are gray with lettering in blue ink. The crystal and right pen stripe are in red ink.
These proceedings are transcripts of recordings which were made during the conference on 78 rpm records. Three of these records presently exist in the archives of Motorola Inc.
I believe that copies of these proceedings are quite rare, however there may be another copy among the personal papers of Dr. Virgil Bottom. These have been entrusted to Roger Ward for several years but will soon be going to Dr. Richard Thompson at McMurry University.