Friday, March 20, 2009

Charles Herrold, Pt. 2

Originally published in the February, 2009, Old Radio Times.(

Charles Herrold: A Father of Broadcasting
Barry Mishkind

Charles "Doc" Herrold
A decade before Frank Conrad built the radio station that would become KDKA as part of a bet on the accuracy of his watch, Charles Herrold was experimenting in San Francisco. But it was the initiation of voice transmissions from his "Herrold College of Wireless and Engineering" at San Jose, CA in 1909 that made Charles "Doc" Herrold a true pioneer.

Herrold was born November 16, 1875 in Illinois. His father was both a farmer and inventor. With this sort of example, it was natural that Charles was also keenly interested in science and mechanics. Like his father, he was an inventor, developing new products in many fields, including dentistry and surgery, photography, and music.

As part of his early love of astronomy, he invented a clock driven telescope. However, it was the loss of his school's only astronomy professor that caused him to move to physics, and electricity and the wireless took over his life.

Eventually Herrold built a 15 watt spark gap transmitter. He wanted more, however, than just telegraphy. He wanted to transmit voice information. A carbon microphone was connected in series with the B+ high voltage supply to the spark transmitter. As much as 50 watts of output power could be developed this way.Early listeners begain to hear "This is the Herrold Station" or "San Jose Calling". The call letters "FN" were adopted for a while, as were 6XE, 6XF and SJN. However, transmission time was curtailed by the need to replace the carbon element every one or two hours. Improvements were made, leading to the invention of the "Arc Fone." The Arc Fone was essentially six arc lights in series which developed a high frequency arc carrier upon which voice could be carried. At first, the necessary 500 volts was tapped from the streetcar lines. A special water cooled microphone had to be built to prevent it from burning out. The Arc Fone was patented on December 21, 1915.

In the meantime, Herrold had decided one of the best uses for his invention was to feed the interest of experimenters with regular programs that would publicize his College. He set up a listening room with chairs and 24 sets of receivers at a local furniture store. Later he would set up another transmitter at the Fairmont Hotel in San Francisco, becoming a pioneer "two way" broadcaster in 1912.

- Barry Mishkind, aka RW's "Eclectic Engineer," can be reached at 520-296-3797, via the Internet. You can find his home page at


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