[AMRadio] What's A Compactron?

Merz Donald S merz.ds at mellon.com
Thu Apr 1 12:40:30 EST 2004

I went out and read up on this and wrote up the following summary. With thanks to those of you who replied--I may have stolen some of your words. Unless anyone has a problem with this, I may send this in to ER in case others would find it useful.

What qualifies a tube as being a compactron? The name "Compactron" is a marketing name General Electric used in 1960 (shortly after the release of the first RCA Nuvistor tube) to signify a new type of tube. GE created the name for much the same reasons that RCA created the Nuvistor name-because they didn't want their new products to be considered as vacuum tubes! 

GE's marketing goal seems to have been to sell Compactrons against both tubes and transistors. In both cases, GE said that Compactrons would be cheaper because you needed fewer Compactrons than tubes or transistors to do the same job. GE also claimed that Compactrons would be "smaller than tubes", would outperform tubes and transistors, and would have long life and reliability.

GE further claimed that the Compactron was the first tube designed specifically for printed circuit board devices, though this claim seems dubious. The Compactron was released with a new "Duodecar" pinout configuration. This is 12 pins arranged in a ¾ inch circle with a gap to act as a key and no base-just a glass button like the well-established miniature tubes of the day. The new base almost immediately spurred RCA to release it's own new tube base configuration--the "Novar". Over time, all these button type based tubes with 9 pins or more have come to be referred to as "Compactrons."

While multi-section types (triple-triodes, double-triode/diode, double-diode/pentode, etc.) were the focus of the Compactron tube lineup, single section types were also included-even in the initial release of 6 Compactron types. Compactrons had a ready market in the TV manufacturers. There was even some public discussion by GE about including capacitors and resistors in the Compactron circuit envelope. But nothing ever came of this idea. 

Compactron sweep tubes found another willing market as final tubes in Amateur Radio transmitters, transceivers and amplifiers. Excluding the amplifiers (too numerous to list), it looks like Heathkit aggressively deployed Compactrons in its product line, as did Yaesu. Drake also eventually adopted Compactron finals in a big way.  

--Don Merz 
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