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1925 Masterphone
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In the 20's battery sets were operated
from a series of batteries, all required "A" batteries (tube
filament supply, "B" batteries (high voltage or plate supply)
and some required "C" batteries (bias supply).
Most used a 6 volt car battery for the
"A" supply, some sets (especially so called portables) used low
filament drain tubes that would work from 1.5 volt dry cell
batteries.
The "B" requirements varied from 22.5
volts to 135 volts with many using multiples of these.
The "C" battery was required when
tubes designed for more power in the output stage were introduced,
these were usually 4.5 volts and some sets required several.
The best way to operate a battery set
today would be with a quality power supply designed especially for
early battery radio operation, such as the
ARBE III (this
is what I use and recommend).
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