FYI,

The tubes designed to work on 12 v for the plate might be best, but there
are a number of battery filament tubes that also migh give you some
results. eg. 1L4,1T4,1U4,1R4,1R5, etc (all 7 pin miniatures). (there was a
series of 8 pin octal tubes, too). Most of them ran filament voltages of
1.4 volts at 50 ma current. I built a audio oscilator with a 1T4 (pentode)
as a kid and it would oscilate down to 7 volts on the plate!! Most of those
tubes were designed for up to 90 v on the plate. Power audio tubes were like
3S4, 3Q4, 3A4, etc (which would run 3.0 v at 50 ma, or center taped filament
at 1.4 v and 100 ma). The 3A4, pentode, as RF amplifier was good for
something like 1/2 watt output or so, not bad for QRP and no transistors.

There was an older series of battery fillament tubes, designed for lead
acid cells (all were 2.0 v on filaments and not much amperage, either).
You'll have to consult an older tube manual for those if you want to try
them.

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On Sun, 7 May 2006, wrote:

Anybody know any tubes...st or gt shape preferred that will work on 12
volts plate voltage for small 1 tube regens...possibly a stage or two
of amplification also.

I know there were automobile radio tubes made that didnt need vibrators
but dont know any numbers myself.