22 Apr
2005
22 Apr
'05
9:33 a.m.
From: ard at p850ug1.demon.co.uk
Hi
Higher quality AM receivers used the two diode tubes.
One diode was for the detector while the other was
used for the AGC. That way the loading could be optimized
for each function.
Dwight
It has a B9A (9 pin miniature) base,
Certainly, multifunction tubes were around - the
first ones were the dual
diodes and rectifiers of the 1920s, then later twin triodes, extra diodes,
and yes, to the ultimate Compactrons.
The most complex common multi-section valve in the UK (i.e. with the most
sections), is the triple diode triode. It came with a variety of heater
ratings -- the EABC80 (6.3V heater), UABC80 (100mA series string heater,
by far the most common version) and the oddball PABC80 (300mA series
string heater). It turned up in numerous AM/FM radios in the 1960s, where
it was used for the AM detector (1 diode), FM detector (the other 2
diodes) and audio ampifier (triode). so there must be some commoning of electrodes going on,
probably the
cathodes.
-tony