12-21-2020, 06:24 PM
i'm working on a [Radiola] 7070 radio from a 1947 ford [ https://www.radiomuseum.org/r/ford_7070_...05_b2.html ]. basically the same as a Zenith 6MF780.
not a transitone obviously, but i searched for "spark plate" and came up with one other thread. which led me to think that philco did use them.
the radio works perfectly, but one of the spark plates measures 4-5 ohms to ground yet reads 6 volts when the radio is on, and the radio only draws 4 amps with or without the spark plate in the circuit. no short thru the spark plate that is, in spite of the low resistance. the resistance of the other spark plate is infinite, which it should be, i think. it measures 600pF.
i see no damage to the one with the low resistance. but worry that it could short out. am i missing something here??
could i just replace the spark plate with a 600 pF cap, say rather than try to rebuild it [it's riveted on.]?
or just eliminate it entirely?
PS
Antiqueradios had several threads but not a definitive answer that i could find.
not a transitone obviously, but i searched for "spark plate" and came up with one other thread. which led me to think that philco did use them.
the radio works perfectly, but one of the spark plates measures 4-5 ohms to ground yet reads 6 volts when the radio is on, and the radio only draws 4 amps with or without the spark plate in the circuit. no short thru the spark plate that is, in spite of the low resistance. the resistance of the other spark plate is infinite, which it should be, i think. it measures 600pF.
i see no damage to the one with the low resistance. but worry that it could short out. am i missing something here??
could i just replace the spark plate with a 600 pF cap, say rather than try to rebuild it [it's riveted on.]?
or just eliminate it entirely?
PS
Antiqueradios had several threads but not a definitive answer that i could find.
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