[Amps] YC-257 VS 8877

[Tom W8JI]

> There is o significant difference worth mentioning. The 
> filament voltage of the 3CPX1500A7 is
>  specified by Eimac to br 5.5 volts at 11.2 A while the 
> 8877 is specified at 5.0 volts at 10.5 A.
>  If the amplifier filament transformer only produces 5 
> volts, it may reduce the life span of the YC-257 since the 
> filament will be 10% lower than specified.

I think you will find the internal structure other than 
better insulation is the same as an 8877 and that Eimac only 
runs the regular filament/cathode hotter by jacking up the 
filament voltage. Other than some very small physical 
changes to the envelope the internals are the same. That is 
recollection when I was considering running a YC-257. That 
being the case emission life should be longer at 5.0 volts 
provided peak cathode current is kept within 8877 limits.

Maybe someone can actually contact Eimac instead of 
guessing.

73 Tom