OT Don't read this (was Re: Altair MBL source)

[Dwight K. Elvey]

>From: ard at p850ug1.demon.co.uk
>
>> 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).

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, 
>so there must be some commoning of electrodes going on, probably the 
>cathodes.
>
>-tony
>
>