Evolution of US Radio

Author: Al Welch

One thing leads to another. After the telegraph came the telephone and then came "wireless". From the electric light bulb evolved the vacuum tube. Italian Marconi is credited for invention of the first radio concept, the wireless telegraph, Marconi sets consisted mainly of huge capacitors, a huge antenna, a headset and a key for transmitting messages in Morse Code. The wireles spread rapidly but not quickly enough to save passengers of the Titanic. At Marconi-USA, Sarnoff received the distress call from Titanic and the story was in the New York Times long before a rescue ship could come to the scene.

The disaster awakened the sleeping giant as to the need for reliable radio communications. Radio to carry voice and music required much better technology and Americans such as Armstrong and DeKalb contributed greatly. Edison labs and RCA contributed to development of the vacuum tube.The photo above shows the progression of tubes from the large antique balloon tube on the left to the first solid state device, a selenium rectifier, on the right.

The first two large tubes used the standard tube socket design which oriented the tube using two "fat" pins. About 1936, the industry created dual function tubes in the form of the 6A7 pentagrid converter and then the octal tubes. Philco developed the snap-in "loctal" tube, third from right.

Miniature tubes, 2nd from right, were developed for special applications but military demands in W.W.II made these the industry standard following the war. The selenium rectifier began to replace rectifier tubes in the 50s and was a harbinger of a solid-state revolution.

The lower horizontal tube is a "Magic Eye", a popular tuning aid in radios of the late 1930s. Many different electronic schemes appeared in radio receivers. Some were called cascades, some were regenerative receivers. The TRF, tuned-radio-frequency, was the first high performance receiver. Eventually the TRF gave way to Armstrongs design, the superheterodyne. The functionaL, practical advantages of the superhets made the design the final standard.

The Radio Cabinets

Attwater Kent 20's

The first commercial radio station began operations in the United Statesin 1920. With the first radio stations came companies like Attwater Kent, which made the early commercial radio receivers. The first receivers had an assortment of tubes and components placed on a flat base and have come to be termed breadboards. The example below is an early Attwater Kent.

Attwater Kent had his own company which led the radio industry for several years. In the 1930s, Kent closed his factory rather than negotiate with labor unions which he considered communists. The following phase was the "coffin" cabinet, a horizontal box cabinet with an access door on top. This coffin style radio below is a Radiola, which was an RCA product. GE bought Marconi-USA and created RCA, the Radio Corporation of America. RCA helped advance American communications and formed the NBC network. The company wasn't profitable in the 60s and residuals of RCA were purchased by General Electric in 1982. The RCA logo is owned by a French company today and todays "RCA" products are imports from Asia.

Late in the 1920s, console cabinets became popular. There were skilled woodworkers available as evidenced in the example below, a Coronado "low-boy" cabinet with a 7 tube tuned-radio-frequency chassis. Coronado radios were sold by Gambels/Skogmo stores.

Table radios improved in the '30s. Manufacturers began building the speakers into the cover of the cabinet and in the early 30's came the tombstone style. This is a rectangular cabinet that stands upright with the speaker mounted above the chassis. The Tombstone below is also a Coronado.

I bought the Majestic Chrome front Tombstone below for $15 and spent the next two years restoring it. This radio is a model 161 made in 1934.

Majestic Chrome front Tombstone, model 161, 1934

Marketing style, manufactures used the cathedral design. Philco established themselves as a leader when cathedrals became very popular in the mid 1930s. Philco 90 below.

Philco 90

In the midst of the depression most Americans were poor but there was a very very rich class of consumers. Zenith utilized the abundant labor supply and materials to create a wide range of elegant consoles aimed at consumers for whom price was no object.


Sears Roebuck sold many radios with the Silvertone name. Nonewere finer than the model 6230as shown below. This radio features a quality Ingraham cabinet, a magic eye tuning tube, two bands and push-button tuning. The 6230 was made in 1939.

6230 was made in 1939

In the late 30s and early 40s, more compact and functional table radios appeared as indicated by the GE and Stromberg-Carlson sets shown here:

GE and Stromberg-Carlson sets

After W.W.II, intense competition set in. Materials were in short supply and labor became more costly. Bakelite plastics gave way to polystyrene. Everybody made the "All American Five". A five tube AC/DC radio using mostly a standard set of five miniature tubes and a permanent magnet speaker. At this time the clock radio was in demand and some wanted one in every room of the house.

radios from Crosley and a Bendix

Above: Clock radio by TravLer top, bottom two clock radios from Crosley and a Bendix

Al Welch

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