B batteries provided the high voltage to the "plates" of tubes. I recall 90
volt units.

A batteries provided filament voltage (1.5 volts) to a lot of tubes like the
1EQ5, where the first digiot indicated the filament voltage, and the letters
the type of tube characteristics, and the final digit the number of pins that
were active.
6 AQ 5 was a 6 volt amplifier with two filment connections, a plate
coonection and two grids.
However sometimes there was a cathode too (I'm getting hazy on this stuff),
maybe the filament didn't count as two.

BTW, your question brings up an interesting point.
You slightly mislead us by talking about battery sizes (defined by NEDA?)
A, B, C, D, and AA and AAA

But in the old days, the usage designations were widely used A was for
filament, B for plate supply and C for tube bias. If your tube plates needed 90
volts, the grids might need 45.

You used C batteries because to drop the voltage from a B battery was very
wasteful (resistor heat), and batteries were expensive.
The B batteries were almost always square or box-like, and C and A could be any
shape. The D cells were used for illumination (dial lights and the like).

Batteries could be designed for high current, low voltage, or low current high
voltage, or some variation thereof to suit the purpose.

Even today, if you go into Radio Shack and get the l;ittle coin-sized
batterries used in calculators and the like, you'll have several different
versions of the same shape.

Some have their internal chemistry optimized for low current, long life
(digital clock or memory battery backup in a PC), while others are designed for
infrequent bursts of high current draw (garage door openers). That is why if
you're in a bind, you can probably substitute another battery number for one
that's not in stock, but it won't last as long because it won't be optimized
for the job. But the size has to be the same, of course.

(Radioman390) wrote in message ...
B batteries provided the high voltage to the "plates" of tubes. I recall 90
volt units.

A batteries provided filament voltage (1.5 volts) to a lot of tubes like the
1EQ5, where the first digiot indicated the filament voltage, and the letters
the type of tube characteristics, and the final digit the number of pins that
were active.
6 AQ 5 was a 6 volt amplifier with two filment connections, a plate
coonection and two grids.
However sometimes there was a cathode too (I'm getting hazy on this stuff),
maybe the filament didn't count as two.

And "C" cells provided the bias voltage. This was before cothode resistors
became common. I built such a radio years ago. 3 stage TRF. I used "hearing
aid" vacum tubes, with several hundred turns for a "loop" andtenna around the
edge. It was about the size of a VHS tape, but about a third thicker.
Terry

On Sun, 3 Oct 2004 07:41:17 -0700, "Keyboard In The Wilderness"
wrote:

Hey I can buy A batteries, (AA, and AAA), and C batteries -- right
What happened to the B battery ???

They fell out of use after portables requiring a high plate
voltage source were no longer made -- age of the transistor.

I used to have one such radio in the 50s. I believe they pot
out about 90 volts.