By Dave Jensen, W7DGJ

We're all familiar with the big names in radio history, but perhaps not with the names of two brilliant radio innovators, Irving Langmuir and William C. White. These two cousins both worked at General Electric R&D during its heyday (1910-1960 or thereabouts). For me, the story of these inventors and their GE colleagues has a strong personal connection. That's because I grew up in a family surrounded by all things General Electric, where imagination and innovation not only drove a business but pulled my family along with it. (If a "sub-standard" Westinghouse lightbulb had been discovered in our home there would have been hell to pay.)

Dad ran the General Electric Lighting Institute at Nela Park; Nela Park (Cleveland, Ohio) was one of two giant R&D centers where General Electric fostered innovation at the time. A huge number of inventions came out of these centers. . . Nela Park and GE Schenectady (formerly Edison Electric) produced some of the most important products for the corporation, including a number of ham radio innovations. (Single-sideband, for example, developed nicely from basic R&D initiated in these facilities.) I'd argue that after Bell Laboratories R&D, these two facilities were the leading career locations for brilliant people like Irving Langmuir and his cousin.

As in the Bell Laboratories demise, those days are gone. Nela Park may have been the first corporate research park in the USA but that didn't matter when GE broke up and was sold off. The history-making landmark in Cleveland -- 90+ acres complete with stunningly beautiful historic buildings -- was sold off for pennies to a residential developer.

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The Langmuir Laboratory Jumps into Radio

Dr. Irving Langmuir was a New York born chemist, physicist and engineer who took an interest in radio at the time that new discoveries were being discussed from people like Howard Armstrong and Lee de Forest. His younger cousin, William C. White was a Columbia University graduate in electrical engineering. An amateur radio operator, White loved to work with his amateur radio on the weekends and rare evenings when he wasn't working at the GE labs.

Upon joining GE after graduation, William was assigned to the Langmuir lab where Langmuir put him to work across many different projects, including vacuum tubes.  (See photo of Langmuir with Edison examining his largest amplifying tube at the time.)

Dr. Langmuir was the consummate curious scientist, whose interests could run across any number of different areas due to the many disciplines he had taken up. This meant that he often crossed over from chemistry to metallurgical engineering to films and physics, and from filaments for light bulbs to the new field of vacuum tubes (DGJ: very similar to lightbulbs.) It was Langmuir's habit to set forth in an area of exploration, make the discoveries and write up the scientific papers, and then pass on the innovation to his cousin William. He was the fellow who could then be counted on for the actual implementation of the design into a commercial product. (See the photo of White standing next to a row of vacuum tubes he brought into the commercial market.) When General Electric received an order for 80,000 vacuum tubes from the US Government, it was William White who developed and scaled up the process for manufacturing.

The years of 1910 to 1915 were absolutely wild and crazy in the field of improvements to radio.  After the vacuum tube was invented, Lee de Forest stepped in to innovate, resulting in the Audion tube -- a type of vacuum tube that amplified an electrical signal. It was immediately taken up by AT&T for long-distance telephone service.

The Audion tube fascinated Langmuir and White in their labs at General Electric. They suspected that if they took their knowledge of gases, filaments and tube-manufacturing prowess, a bigger and better tube could be developed that would be suitable to amplify radio signals. The photo to the left shows just a few of those. The work that Langmuir and White did on tubes later resulted in a popular model that could be used in 100kW stations.

The Regenerative Circuit

The "wild west" nature of these early radio days was really on display during this period, as 5+ laboratories around the world were working on a system of regeneration, where some of the output of the amplifying tube is applied back to its input, resulting in increased amplification. Each of the many innovators working with this circuitry had their own timeline of discoveries; they all came forward when the US Patent Office began to determine who would get this very lucrative US Patent.

De Forest had added a third element, the grid, to the original vacuum tube (the Edison-Fleming diode). One day in 1912 he accidentally connected the output circuit of one Audion to its own input circuit and obtained a loud howling sound, something he later identified as regeneration. But the patent office knew by the way it was presented that the inventor didn’t understand why it was happening. (Initially, after hearing the howling sound that resulted, De Forest had tried to abolish it -- which didn’t add any favor to his application.)

However, when Howard Armstrong began experimenting with the Audion, he took careful note of how the process of regeneration functioned and made clear the circuit designs that allowed it to operate as a powerful amplifier of incoming radio waves; the result was a much more powerful patent application. He also discovered that when the resulting feedback was increased, the same circuit could be used to transmit high frequency oscillations. It resulted in a new type of generator for radio signals.  

It had taken 20 years, and thirteen different court actions by 30 different judges, to settle the US Patent matter. It finally arrived at the US Supreme Court. As with many high-tech issues, the difficulty was to explain highly technical matters to people who have only a basic understanding of the subject. Lee de Forest and his attorneys were finally successful, but over time all of the engineers I've read who have commented on this matter give the credit for the regenerative circuit to Howard Armstrong. (Photo is Armstrong's first regenerative radio set.)

To show you how crazy the world of patent applications was at the time, Armstrong's package of materials arrived at the US Patent Office on the morning of October 29th, 1913. An equally strong and perhaps even more scientifically laid out application arrived from Irving Langmuir of General Electric, on the same day, but later in the afternoon. As a result, it was put aside as arriving after Armstrong's application. If Langmuir and his colleagues had allowed just a bit less formal review and editing, it could have arrived first and history would reveal a different winner of this particular horse race.

Anyone interested in the history of early radio should definitely check out the Ken Burns documentary on the topic, called Empire of the Air -- The Men Who Made Radio. There's also an interesting (but perhaps a bit dry) book which inspired the video.

73 for now,   Dave Jensen W7DGJ

Questions for discussion -- please join us at the link below.

- Clearly, vacuum tubes were an important part of radio history, but they are still in use. Please tell us why you own tube equipment and what benefits are you achieving in your station?

- Does today's US Patent Office operate in the same manner, where two applications received on the same day would see one of them tossed out, as Langmuir's was for the regenerative circuit?

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