[BC] 4CX400C

[Brew]

Kevin says:

> I used to use the Amperex 4-400s in the CCA AM1000D at WCKI,
> but they would go flat faster in the RCA for some reason. The RCA
> always did good on the Eimacs, but the CCA did not like 'em.

Originally the CCA AM1000D used 4-400A (or maybe C?).   There was a
tapped wire wound resistor to adjust the screen voltage (I think it
was adjusted to get the S/N numbers down, not sure).

By the time I was testing AM-1000Ds in the CCA factory in Gloucester
City in 1974, we'd switched to Amperex 7527A tubes (which I think was
the Amperex replacement for the 4-400C).  The plate was a piece of
solid carbon like stuff.  You put them in, turned it on, and the rig
made power and S/N ratio was fine.  Distortion was around 2.5%, even
below 2% in the middle of the audio spectrum.  The tapped resistor was
no longer used, it was replaced with a fixed wire wound resistor of
the same value.

The 7527A tubes are listed for $80 a piece at
http://www.audiotubes.com/bjtubes.htm

Sounds pretty cheap, wonder if he still has any?

brew  Bruce Schiller  CBS-TV NY Master Control Maintenance and WA2ZST