I've come across a clearly marked Tung-Sol type 257 Power Pentode. this is unlike the type 57 sharp cut-off amplifier that we all know. It is in a globe shaped envelope and in all ways appears to be identical to a type 47 or PZ except that it has a 6.3 volt filament, presumably for use in Automobile radio service. . I vaguely remember reading a description of this tube in some vintage magazine some years ago, but I have been unable to find any information since. Does anyone recall any sets which use this odd duck?

Hi Bob

Tube Lore says it's a power pentode with 6.3 volt @ 300 ma filament. "800 mw output for DC line operated receivers like Fada". Made by NU and TS. NU filament was 5 volt.

I've never seen this tube used.

Norm

:I've come across a clearly marked Tung-Sol type 257 Power Pentode. this is unlike the type 57 sharp cut-off amplifier that we all know. It is in a globe shaped envelope and in all ways appears to be identical to a type 47 or PZ except that it has a 6.3 volt filament, presumably for use in Automobile radio service. . I vaguely remember reading a description of this tube in some vintage magazine some years ago, but I have been unable to find any information since. Does anyone recall any sets which use this odd duck?

hi bob,
sorry to bother you in the wrong forum! i have a question re: cabinet restoration-something you posted few months ago...can you pls check my question? it is burried back under your original post! many thanks!