Silicon Valley was Built on Tubes of Glass



Lee de Forest

Bill Shockley brought the transistor to a pasture in Palo Alto, but he didn’t land there by chance. There was already a plot afoot which had nothing to do with silicon, and it had already been a happening place for some time by then.

Often overshadowed by Edison and Menlo Park or Western Electric and its Bell Labs, people forget that the practical beginning of modern radio and telecommunications began unsuspectingly in the Bay Area on the shoestring-budgeted work benches of Lee de Forest at Federal Telegraph.

As the first decade of the 20th century passed, Lee de Forest was already a controversial figure. He had founded a company in New York to develop his early vacuum tubes as detectors for radio, but he was not very good at business. Some of the officers of the company decided that progress was not being made fast enough and drained the company of assets while de Forest was away. This led to years of legal troubles and the arrest of many involved due to fraud and loss of investors’ money.

De Forest, who thought that the only problems in his way were technical and could be solved in time, made his case to Federal Telegraph. In very short order his early patents were licensed to others including Bell Labs who quickly developed them into the first telephone relay tubes.

Federal Telegraph was interested in the development of Continuous Wave (CW) radio as opposed to the then more common spark type transmitters. The technology was developed by Valdemar Poulsen in Holland, and used an arc converter transmitter to produce a stable sine wave that was more efficient and less noisy reducing interference with other stations. With this in mind, Federal and de Forest realized that de Forest’s tube could be used for linear amplification and could be applied to it for modulation of speech transmission.


1 MW Federal Arc Converter Transmitter

Most of de Forest’s enforceable patents expired in 1925, and an arms race took off with companies such as RCA, GE, Sylvania, and Westinghouse. At that time these companies were aggressively pursuing, mainly through patent litigation, new companies developing better tube technology.

To get the real story you must follow three very important people who worked at Federal and their subsidiary, the Heintz and Kaufman tube company. Charles Litton, William Eitel, and Jack McCullough were all amateur radio operators and understood the limitations of the currently available tubes being offered by large eastern firms.

Litton in particular spent much time devising machinery and new practices at Federal Telegraph’s Heinz and Kaufman tube division that not only side-stepped other patents, but got him many of his own. Soon, Federal was making better more reliable tubes capable of higher efficiency and frequencies than the large makers. Unfortunately Federal Telegraph was acquired by ITT. In their race to consolidate companies they slashed Federal’s budget and moved operations to New Jersey before the new tube designs could attain market success. This led to a technology gap between what was available and what these men knew could be done. Necessity being the mother of invention, these three founded companies to produce these designs and kick off modern radio communications electronics.


Eimac Power Tube, CC-A-SA by Jeff Keyzer

Unwilling to move with Federal to New Jersey, William Eitel and Jack McCullough founded Eitel-McCullough (later shortened to Eimac) to continue producing new and better power tubes, selling them directly to hams and engineers alike. At the same time, Charles Litton founded Litton Engineering to design and manufacture laboratory grade tube assembly equipment for any company wishing to enter the business. His glass lathes are still to this day the standard in the laboratory glass working industry. Together these two companies laid down the fertile soil from which precision high power designs could grow.

Enter Frederick E. Terman

A New Arrangement Between Business and Academia

Widely regarded as the father of what we consider electronics today, Frederick E. Terman’s 1955 fourth edition of Electronic and Radio Engineering still stands as the best textbook on classical electronics and radio engineering. Terman attended graduate school at MIT and saw how eastern business and education operated. He thought that if true advancements were to be made a new attitude toward commercialization of research discoveries was needed.

Terman returned to Stanford as a member of the faculty and his first order of business was to hire Charles Litton and Carl Spangenberg to help him found his Vacuum Tube Laboratory. Spangenberg later went on to become a tube industry expert and writer of the book simply titled Vacuum Tubes. The result of these first hires was a lab dedicated to educating students in not only electronics, but the manufacturing methods needed to push the field forward — a very novel approach in those days. In 1938, Charles Litton gave a $1,000 grant to the lab to hire Terman’s favorite student David Packard on and Bill Hewlett was brought in by Karl Spangenburg. Charles Litton served as a mentor to Bill and Dave in the founding of Hewlett Packard in 1938.

From Radios to Radar

Tube technology in the valley didn’t constrain itself to radio communications. An important invention from brothers Russel and Sigurd Varian affected radar research throughout the world. The British were already using radar system, but the weight of those designs prevented radar from being deployed in aircraft. The Varian’s invention of the klystron solved the weight problem.

Russel and Sigurd Varian were born in California. Russel attended undergraduate school at Stanford, worked in the oil industry earning him his first patent for a vibrating magnetometer, and later worked under the great Philo Farnsworth. Sigurd was not very successful academically, and left college to work a number of different jobs. He found his way into the aviation industry as both a pilot and mechanic. While flying, he would envision the need for an electronic navigation and warning system to allow safe travel at night, in bad weather, and likewise identify the location of a plane in flight from the ground for defensive systems. Russel suggested this could be accomplished with microwave signals. With an eye towards the unavoidable war with Germany they set about to create their system. They failed, at first.


The First Prototype Klystron

Enter their friend William Webster Hansen. At this time William was a professor at Stanford and on his recommendation the physics laboratory (and not the tube research lab) decided to hire the brothers to develop their system in exchange for lab space and a small budget with the understanding that half of any royalties earned from their discoveries would be shared with the university.

With this backing they developed their own method of velocity modulation in 1937. Velocity modulation had already been demonstrated by A. Arsenjewa Heil and Oskar Heil in 1935, but not published anywhere the Stanford team would have found it. Russel designed, and Sigurd figured out how to build the first klystron, the first practical mobile microwave device. The brothers, Hansen, and Edward Ginzton founded Varian Associates. Now called CPI for Communications and Power Industries they continue to produce power tubes, klystrons, and magnetrons and now own Eimac as well. They also were instrumental in creating radio therapy and radiation treatments for medical use in oncology.

Valley Talent Recruited for War Effort

The war effort put intense focus on the development or radio technology. All of these scientists were hired by New England firms and universities to work on radar systems. Much of it was never made public, but many advances made in tube manufacturing techniques were made during this time. In particular, Charles Litton was the one who made microwave tube manufacturing possible using new tube manufacturing methods he had pioneered.


Groundbreaking for a Kodak Factory, Stanford Research Park, 1953.

After the war all of these men returned to their businesses in California. Eitel-Mcullough, Litton Engineering, and the Varian Brothers, Bill and Dave, and the Stanford professors were well versed in selling tubes to the military and what the road map ahead of microwave design would be. Whole new areas of high frequency design and experimentation were now unfolding at a rapid pace, enabled by the research done on the radar projects and the now available war tested high power microwave products now available and Stanford wanted to be the place business went to to commercialize these new technologies.

Fredrick Terman realized that they needed to entice companies into investing with Stanford. Proximity seemed to be a good place to start. The decision was made to set aside some university land, most of which was either marsh or farm land at the time, to develop into the worlds first industrial park. Varian Associates were the first tenants, followed by HP, GE, and a number of aerospace firms such as Lockheed.  The businesses got cutting edge research and the university got industry-leading guidance and assistance, and most importantly funding. This partnership is really what started technology in the Santa Clara Valley, not transistors.

Goodbye Glass Tubes, Hello Semiconductors

Nobody would deny that the solid state transistor would change the world. In microwave the smaller you can make a device the more efficient it will be, and these companies understood that. They also understood they needed to be at the forefront.

William Shockley, having grown up in Palo Alto, needed a place to set up shop. He had burned his bridges at Bell Labs, and some of his colleagues there felt he did not deserve his acclaim as inventor of the transistor. Stanford was now producing world class engineers fully up to speed in the newest technologies. The Valley was the logical place for him to go.

William Shockley. Evidently nobody liked him, but that’s another story.

Sources for this Article:

You should read The Secret History of Silicon Valley by Steve Blank. Its an excellent book that covers many topics not touched on in other typical Silicon Valley books. Much of the information in this article was sourced there, but is backed up with the countless conversations I was blessed to have with retired engineers in my personal research into the history of vacuum tubes and technology. I would like to thank them all, but many of them are unfortunately no longer with us.

I would like to thank in particular Mr. Howard M. Brady who passed away several years ago. He worked for Federal Telegraph during their New Jersey years and also with Chatham, United Electronics, and Electron Technologies Inc where he was still making strides in research in high vacuum measurement technology right up until the end. When the world was in trouble, he was one of the “experts” who was called to consult with when the answers couldn’t be found in any textbook. Many of the devices and techniques he developed as far back as the late 50’s are still considered trade and security secrets. Over the course of many pleasant conversations he gave me directions to research to put together the story of why things are the way they are in electronics and on who’s shoulders we really stand.



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