"Ed Huntress" wrote in message
...
On Wed, 19 Aug 2015 22:43:23 -0500, Martin Eastburn
wrote:

Small tubes were popular in Hand Transceivers and all
sorts of stuff. Battery radios had them. Typically they
drew lower current on the filaments (heaters) and had them
on one battery. B+ was on another battery.

I got rid of my 1T4's just a few years ago. That was 1.5V filament,
and the B+ was 45V, IIRC, which was an Eveready about the size of a
pack of cigarettes. My first shortwave radio used them -- a one-tube
regen that would run for a long time on the 45V and a D-cell.

The US military was developing a new "vacuum tube" configuration,
for
the sake of their higher (but not total) EMP resistance, around 15
years ago. They were ganged in groups, with the "tubes" being
cavities
cut in blocks of some kind of ceramic.

In the early 90's I dreamed up an alien sci-fi technology that had
never invented transistors, instead they made repairable integrated
tube circuits for their spacecraft by soldering the elements onto a
printed substrate in a large chamber ventilated to space. When the
gain decreased they repainted all the cathodes with Caesium or Radium
in an Argon glove box.

I mentioned the idea to an engineer at work (Mitre) who told me about
ongoing research in that direction.
http://science.dodlive.mil/2013/12/0...ps-meet-tubes/

-jsw