10 Nov
2005
10 Nov
'05
7:37 p.m.
From: "William Donzelli" <aw288 at osfn.org>
Running tubes at low plate voltages was not really an
innovation -
engineers had always done this, and many normal tubes will actually work
at a quarter rated plate voltage or less. Purpose built low voltage tubes
never took off too well - ther really is not a huge advantage in the power
department, as the big share of the power bill was always the filament.
I have a couple of valve (tube) radio circuits with an HT (B+) voltage of
only 3V. Mullard made a range of valves designed for 12V anode, and 12V
heater use (intended for car radios in the late50s - they were used as the
RF and IF stages, driving a Germanium power transistor (usually OC16) as the
AF ouput.
Jim.