[Boatanchors] Anyone remember Tubesters?

[jhhaynes at earthlink.net]

I think the first were some things called Fetrons, made by one of the
companies making FETs.  They were designed to be plug-compatible
replacements for vacuum tubes in Bell System carrier equipment.
The circuit had two FETs more or less in series, and they operated
at the full 130V plate voltage of the tubes.  There was a type to
replace the 6AK5 pentode and a couple of types to replace the 2C51
dual triode - seems like there was one type to use if the tube was
used as an oscillator and a different one to use in other cases.
The actual tubes replaced were 407-A and 408-A, similar to the types
I mentioned except for heater voltage.

Then as someone mentioned there was a company making replacements for
the tubes in Collins S-line gear, and they advertised in QST for a
while.

There was a recent article by somebody who replaces tubes in old gear
with FETS. I can't remember where I read it.  But he replaces the tubes
one at a time doing cut and try, and reduces the "plate" voltage down
to something the ordinary FETs can handle.  So you have to do a whole
radio; you can't replace individual tubes with his designs.


jhhaynes at earthlink dot net