Regency TR-6 AM Radio


The 1957 Regency TR-6 AM broadcast band radio is one of the earliest examples of transistor radio technology. Designed by Regency Electronics (then known as I.D.E.A.), it followed by only two years the famous Regency TR-1, the first production transistor "pocket" radio. The TR-6 is not well known, but is among the most collectable of early transistor radios because it featured a large 4" speaker and had an all-leather case, rather than the fragile plastic case that characterized other radios of the genre.

Regency Electronics was the brainchild of former RCA employees, Joe Weaver and John Pies. The parent company, Industrial Development Engineering Associates (I.D.E.A), was incorporated in 1947, the same year Bell Labs scientists Shockley, Bardeen and Brattain invented the transistor.

In October, 1954, Regency brought to market the world's first transistor radio, the TR-1, and less than two years later, the world's first transistor amateur product, the ATC-1 converter. One year later, the TR-6 was introduced.

 Description: The TR6 was based on a conventional AM superheterodyne design with a mixer/oscillator, two stages of 455 kHz IF amplification, diode detector, and a push-pull audio amplifier. By the time it was introduced, Regency had abandoned the 22.5V battery of the TR-1 and had settled on a 9V battery, which became the industry standard.

Top view of the TR-6 circuit board. The oscillator/mixer transistor is visible on the left, next to the tuning capacitor. The two-transistor IF amplifer stages are in in the center and to the right (underneath the audio transformer), and the push-pull audio output transistors can be seen, heatsinked to a metal bracket. The TR-6 used only two electrolytic capacitors (one of which is the aluminum can in the center.) Capacitor failure was a significant problem in the TR-1, so this economy of design was an important advance.  The radio shown here is completely functional and still uses the original capacitors.

The TR-6 used a sheet metal chassis which supported the single-sided printed circuit board. The chassis slides into the leather case and is secured by two screws on the side. An AM ferrite rod antenna provides good sensistivity across the broadcast band.

In the mid-fifties, the transistor's advantage over vacuum tubes was primarily in simple, portable applications, where size and power consumption were important but performance secondary. For most applications, vacuum tubes had a head start of nearly a half century, and it seemed highly improbable that transistor technology could ever catch up. Transistor usage in r.f. applications was initially slow to develop because current gain of early Ge transistors was so low. Transistors used in the TR-6 were color marked on top of their cases, showing they had been hand-selected for the application.


Printed circuit boards had been invented in the 1940s, but it took about a decade for them to find use in consumer electronics. This circuit board was fabricated out of a phenolic material and is quite sturdy and well-made. Contemporary circuit board technology often uses many layers of printed patterns, with the top and bottome layers coated with a solder mask (to prevent solder bridges) and a silkscreened pattern that shows the component outlines and schematic ID labels.

The TR-6 shown here did not work when I acquired it. I worried that one or more of the irreplaceable transistors might be bad, but the problem turned out to be bad contacts caused by oxidation between the brass rivets and the sheet metal chassis. Aligning the radio took only a few minutes. What surprised me was the quality of the sound, which is fully as rich as that from standard 5-tube AM radios of the 1950s, and better than that of most clock radios of the era. When I first turned it on, after it had sat silent for forty years, it came up on the frequency of a local "golden oldies" station playing "Teen Angel."

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