[HBR] HBR -- Part 12

[Tim Shoppa]

Walt writes:
> I'd sure like to know the history of the 6J6. It must have been
> developed around 1939-40 but it is YEARS ahead of the surrounding
> tubes on the nomenclature charts: think 6F6, 6G6, 6H6 ... 6K6 ... It
> was (to the best of my knowledge) the first serious UHF 7-pin
> miniature tube, being rated to operate as a mixer at 600 Mcs and
> working fine as an oscillator in the same territory. I think it
> appeared for the first time in the BC-788 radio (radar) altimeter.
> That was in production in 1942; I don't know how much earlier.

Ludwell Sibley's _Tube Lore_ says that the 6J6 number was registered
in September 1942. The 6C4 miniature was registered a few months earlier, in
May 1942. Another miniature good for VHF/UHF stuff was the 6AK5,
and it was a few months later in May 1943. I'm guessing the
9001/9002/9003 miniatures must've been about the same time
but I don't think they were registered the same way; tubemuseum.org
says 1940.

There were earlier flexible-wire-lead "peanut tubes" going back to
the 20's and 30's, but it looks like to me that RCA at least was
concentrating on the "acorn tube" for UHF purposes - the sockets
for those look incredibly unwieldy.

Tim.