In article ,
"Michael A. Terrell" wrote:

Telamon wrote:

Ever look inside the early VHF to UHF converters? The one I had long ago
that used a 6J6 I believe. The units local oscillator changed frequency
by raising or lowering a shield around the tube. This apparently changed
the tubes elements capacitance to ground and the frequency lowered with
the raising of the shield not unlike the tuning capacitor in many
receivers.


Have you ever seen a Mallory "Inductotuner" for UHF?

No I have not but if you have a link I would like to see one.

Other things I seen done with tubes externally is with those little
acorn type tubes. I have seen them used in a way they pass signals to
one another by pointing their tips together. I can't tell you any more
than that as I had no schematic of the device, which was some kind of
military remote control box that went into aircraft.

--
Telamon
Ventura, California