Voltage Letters

11/20/2006 1:23:15 PMMike L.

What do all of the old voltage letters mean?, ie B B+ A

11/20/2006 3:48:17 PMMark

:What do all of the old voltage letters mean?, ie B B+ A

The B+ is the plate supply voltage. In the old radios it can be 135,90,67.5,45,or 22.5 volts. The A is the filament supply voltage. It can be 5, 1.5 or various other voltages depending on tube filament voltage and/or circuit configuration i.e. parallel or series connections. The C designation is the grid bias voltage. It can be -9,-4.5, or other voltages. In an old radio you may find the C battery still inside the set. I found one several months ago. It had a date of 1923. I was still able to measure voltage with my digital meter. The voltage was close to the rating on the battery. The volage dropped to zero under a small load. Hope this helps

MRO

11/20/2006 4:52:12 PMMike L.

Is there a B voltage?

11/20/2006 5:06:33 PMMark

:Is there a B voltage?

B voltage is the plate voltage for the tubes. It can also be designated B+. B- is the negative usually ground. B- can also be the negative side of the battery on a battery radio.

MRO