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Agilent Purchases Varian


Last week Agilent Technologies announced it had completed its acquisition of Varian Inc..

I note this event, as Varian played a key, perhaps essential, role in the development of UHF television broadcasting. Engineers at Varian invented the klystron, a vacuum tube that could generate a huge amount of power at UHF frequencies. Although Varian sold its electron tube division in 1995, the klystron played such a large part in the company's history that it's interesting to trace its evolution.

I found "An Early History – Invention of the Klystron" by E.L. Ginzton on Varian's Web site. Ginzton wrote that in his first meeting with one of the Varian brothers, Russell, the inventor used traffic on the road from San Francisco to Palo Alto to illustrate how the klystron worked:

"Just picture a steady stream of cars from San Francisco to Palo Alto," Varian was quoted as saying. "If the cars left San Francisco at equal increments and at the same velocity, then even at Palo Alto they would be evenly spaced and you could call this a direct flow of cars. But suppose somehow the speed of some cars as they left San Francisco could be increased a bit, and others could be retarded. Then, with time, the fast cars would tend to catch up with the slow ones and they would bunch into groups."


Varian reasoned that if the velocity of cars was sufficiently different or the time period sufficiently long, then the stream of cars would be broken into bunches and would arrive in Palo Alto in clearly defined groups. This bunching, as applied to electrons flowing within a vacuum tube, is the principle upon which the klystron's operation is based.

In Russell Varian's article on The Founding of Varian, there's a picture of brothers Russ and Sig Varian standing next to Varian's first TV klystron, and surrounded by the engineers that built it.

In 1965, Varian merged with Eitel-McCulough, Inc. Eimac also manufactured several popular tubes used by broadcasters and amateur radio operators. The merged company developed the Klystrode inductive output tube. This technology is still used in virtually all high power (greater than 30 kW output) tube type UHF TV transmitters in the United States.

Varian sold its electron device business to Leonard Green and Partners, L.P., a private equity fund, and members of management in 1995. Together, they formed Communications and Power Industries (CPI). CPI continues the Varian legacy of building high power electron tubes and microwave amplifiers for use in communications, medical, scientific, manufacturing, radar and defense (electronic warfare) industries.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.