I’m a great fan of the Prelinger Archives which is home to so many items like this video I’ve heard about recently from various ham radio email lists.
I like how the components of the earliest electronics and wireless were so basic and ‘natural’. Think of hand made capacitors and resistors using traces of graphite on paper. Valves (or tubes) of course were another story but still capable of being ‘homemade‘.
I love the idea that an accurate, literally rock solid frequency could be achieved using a piece of a very common rock – admittedly a pure piece of quartz cut just so.
This video details the elaborate and meticulous manufacture of quartz crystals during World War 2 by Reeves Sound Laboratories in 1943.
The 41’24” video can also be viewed (free of youtube ads etc) and downloaded via the Prelinger Archives.
Most of the ‘radio quality’ quartz was mined in Brazil which ceased its neutrality in 1942 and joined the Allies.
The story of quartz crystals during WWII is told in ‘Crystal Clear‘ by Richard J. Thompson Jr. (Wiley) 2011.
“In Crystal Clear, Richard Thompson relates the story of the quartz crystal in World War II, from its early days as a curiosity for amateur radio enthusiasts, to its use by the United States Armed Forces. It follows the intrepid group of scientists and engineers from the Office of the Chief Signal Officer of the U.S. Army as they raced to create an effective quartz crystal unit. They had to find a reliable supply of radio-quality quartz; devise methods to reach, mine, and transport the quartz; find a way to manufacture quartz crystal oscillators rapidly; and then solve the puzzling “ageing problem” that plagued the early units. Ultimately, the development of quartz oscillators became the second largest scientific undertaking in World War II after the Manhattan Project.”(from the book’s blurb)
Illustrating the precise angles needed for the AT and BT cuts of a quartz crystal…
You can read more of the detailed earlier history of the evolution of the US quartz crystal industry at https://ieee-uffc.org/about-us/history/uffc-s-history/a-history-of-the-quartz-crystal-industry-in-the-usa. It tracks how early manufacturers developed techniques for cutting and grinding the natural quartz for the most accurate results.
Frequency measurements were made by determining the difference between the frequency of the test blank and that of some reference frequency such as a secondary frequency standard consisting of a one MHz crystal unit controlling a frequency generator which developed a set of radio frequencies having integral multiples of 10 kHz. Measurement of the difference frequency, detected by a radio receiver, was a major problem which was solved in various ways. One of the early manufacturers, E. L. Shideler, used the family piano as an interpolation oscillator. More affluent manufacturers could procure an excellent analog frequency meter from General Radio Co. and within a short time David Packard and William Hewlett developed the HP-200 audio oscillator which not only met a need in the quartz crystal industry but also launched the Hewlett-Packard Corporation.A History of the Quartz Crystal Industry in the USA
Proceedings of the 35th Annual Frequency Control Symposium, pp. 3-12, 1981
Virgil E. Bottom