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WSHU Chief Engineer Paul Litwinovich explores aspects of vintage radio, from the radio sets themselves to the people and technology that made it all possible.

Regeneration Under Glass

P. Litwinovich collection

The rare 1923 National Browning Drake "Regenaformer" table top radio is rich in the history of the early art, a story of collaboration, litigation, competition  and excitement. This particular radio is built in an all glass case which is what makes it so rare. I’ll get into the reasons behind the glass case shortly, but first, who was the National Browning Drake company and what is a Regenaformer?

If you are a long time radio enthusiast or an amateur radio operator all three of those names are probably familiar, but they are not usually thought of together.

The National Company began as Stone and Webster Engineering Inc., a supplier of sheet metal materials to the growing power plant industry at the turn of the century. Looking for an additional source of income and already having shops capable of turning out sheet metal products, Warren Hopkins, president of Stone and Webster, along with associates Walter Balke and Rosewell Douglass, incorporated the National Toy Company in October of 1914. They landed their first order with retail giant Woolworth’s and soon secured a patent for the manufacture of talking toys. By 1916 the company was highly successful, supplying toys to F.A.O. Schwarz, Gimbels and others. By the early 1920 the company added radio components to its product line. Tuning capacitors in particular, are made from plates stamped from aluminum or brass sheet metal.  Soon after, the company dropped the word “Toy” from its name and became “The National Company”.  (*1) The company was located in Cambridge Massachusetts.

In the early 1920s, Fred H. Drake and Glenn Browning, both Harvard engineering graduates, were conducting research at the university on methods to improve the efficiency of radio frequency transformers (note 1), then typically only 20 to 30 percent efficient.    Mr.  Drake suggested (and I quote from his own paper) that they should use “a mathematical treatment of a tuned radio frequency transformer, in order to determine the proper constants necessary for maximum amplification”.  The results when built and tested in the lab proved to work better than he and Mr. Browning had hoped for. (*2)

Credit Paul Litwinovich collection
National Browning Drake company label

Based on their success with their radio transformer design, they went on to develop the “Browning Drake Tuner.” It was a combination of the Tuned Radio Frequency (TRF) circuit, and Lee DeForest’s Regenerative circuit (note 2). DeForest was by now embroiled in patent litigation vs. Edwin Armstrong over who invented the regenerative circuit (DeForest eventually won). (*3)  Browning and Drake approached The National Company to manufacture the tuner and soon a kit radio under the name National Browning Drake was on the market. Later, both Browning and Drake would start their own successful radio manufacturing companies.  In the future, I’ll spend more time on each of them and The National Company, as they all contributed richly to the technology.

The term "Regenaformer" was simply the trade name, more likely a catchy marketing phrase, for a regenerative receiver using the new improved radio frequency transformers that Browning and Drake had developed. Marketing or no, the set was an instant hit with radio enthusiasts. It turbo charged the performance that people expected from the average set. Articles about the new kit appeared in just about all of the radio magazines of the day. The set, like all 1923 offerings was battery powered, and like most regenerative receivers, was a bit complicated to tune. It tunes the AM broadcast band, and would have been used with headphones or a horn type loudspeaker. The model had an extremely long run as radios go, with Regenaformer kits still being sold at the close of the decade.  So where, you may ask, does the glass cabinet fit in?

Credit P. Litwinovich collection
From 1923 “Radio Broadcast Advertiser” trade magazine

In the early days of radio, kit building was very popular. This picture is an advertisement for the "tuner only" version of the radio, intended for use with headphones or to feed an additional audio amplifier and its horn style loudspeaker.  The technology was new and exciting, while at the same time simple enough to be understood by someone with the time and desire to read a few books or magazines about how it worked. Factory-made radios, especially the better ones, could be quite pricey. The kit radio offered similar performance at substantial savings. Kit radios had one other area of advantage, adaptability. The technology was improving rapidly, and the kit radio had the ability to evolve with it. Kit manufacturers could quickly add the newest and improved parts to their kits, and they could offer upgrades to previous models that the hobbyist could install themselves.  The kit industry had become a substantial and highly competitive portion of the early 1920s radio market.

Credit Paul Litwinovich
National Browning Drake sales brochure

The Regenaformer radio was offered to the public as a Bakelite "breadboard style" chassis with a matching Bakelite front panel and Bakelite knobs. Pictured here is the parts layout from a Browning-Drake sales brochure. It is the larger kit with the audio amplifier included, as is the model in the glass cabinet.  It is pictured with the tube sockets empty. The tubes, along with a wooden cabinet and a volt meter to monitor battery life were options offered at extra cost. Tubes were expensive. When a kit builder upgraded, most often the tubes were moved from the old model to the new one.

                                         Why Glass Radios are So Rare

The glass cabinet was never offered to the general public. A limited number of them were made by The National Company as dealer displays, and even then, they were only sent to the largest and most successful venders. A few other manufacturers also made glass display radios. The thought was that the view of all those shiny new high tech components would entice the kit builder into buying the kit. Over the years I have only seen two or three glass radios, quite often the front panel was the standard Bakelite offering that came with the kit, only the sides, top and back were glass.  Often, I have seen the radios misrepresented for what they are, even by qualified antiques dealers, appraisers and serious collectors. Most often, it is assumed that a hobbyist with access to a glass shop built the cabinet of glass to be unique. While there may have been an occasional instance of this occurring, it is not likely. If you should if come upon one of these sets and the glass is perfect, particularly the holes drilled for the knobs and switches, it is almost certain that it is a rare dealer’s display model.  By the mid 1920s kit radios were taking a back seat to the now numerous production sets, and companies stopped using the glass radio as an enticement.

Credit P. Litwinovich collection
Top-lighted “Regenaformer” table top radio

When illuminated from above, the radio simply glows. Pictured here is the tuner end, the large knob on the left is for the RF amplifier, on the right is the regenerative tuner, and the small knob left of it controls the regenerative feedback. Farther to the right is the first audio stage volume control.

Over the years most of these sets were damaged, lost, or scrapped for their parts.  Thousands of the Browning-Drake kits were sold, and it is not too hard to find one in its consumer form on line or in antique shops. Currently (depending on condition) they sell for $150 to $600 and make a nice addition to an early period collection. If you want a glass one though, be prepared to add another zero to the price. There are very few of the glass display models still known to exist. Of those, a few are in museums. If you should find one, or be lucky enough to own one, please let me know about it. The vintage radio community would love to know about it and get a more accurate picture of how many others may still exist.

Credit P. Litwinovich collection
National Browning Drake “Regenaformer” table top radio tuner

On another note, I am curious to see if there are those in the greater Bridgeport, Connecticut area who might be interested in forming an antique radio collectors club. We would probably meet once per month. It would be a good forum to exchange ideas, resources, parts etc. and could be educational for those interested in getting into the hobby. Please contact me via e-mail by using the "contact us" drop box on the WSHU web site.


Note 1:  Radio frequency transformer- A component used to couple or transfer the radio signal between one circuit and the next in a receiver. By design, they may be tunable, fixed frequency, or broadband (able to pass a wide range of frequencies)

Note 2: Regenerative circuit:  A tuned radio frequency circuit wherein a small sample of the output is fed back into the input to be amplified , or “regenerated” over and over again, greatly increasing the amplification of a single tube. If too much signal is fed back, the circuit will break into a howling oscillation.


(*1) “A brief History of the National Company” By John J. Nagle, K4KJ  first published in the Antique Wireless Association Review ,  Vol 1.  Read more at:  http://www.qsl.net/jms/bio_rem/bhnc.html  and Wikipedia http://en.wikipedia.org/wiki/National_Radio_Company .

(*2) Browning Labs web site   http://www.browninglabsinc.com/browning_drake_corporation.htm  and “Evolution of the Browning Drake Receiver” by Arthur H. Lynch, published in Radio News, April 1927 available in PDF format at: http://www.mcmlv.org/Archive/Radio/BDimproved.pdf

(*3)  A History of the Regeneration Circuit: From Invention to Patent Litigation by  Prof. Sungook Hong, available in PDF format from the IEEE archive at:  http://www.ieeeghn.org/wiki/images/0/08/Hong.pdf

Paul was a design engineer and engineering manager in the broadcast industry for14 years before coming to WSHU in 1990. He holds an FCC commercial radio license, and an extra class Amateur radio license.
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