[legg]

On Mon, 30 Jul 2012 13:01:32 -0500, legg wrote:


Anecdotal info suggests that ECC85 (6AQ8) was developed and marketed
after ECC81/12AT7, and that ECC85 was developed specifically for VHF
input/oscillator combinations. An improved inter-device screen
supposedly reduced oscillator stage radiation. This isn't an
input/oscillator schematic application, in any event.Not sure what
6BK7A does that's special.

When converting from 6BK7 to 6AQ8 or 12AT7, the cathode bias resistor
in self-bias is supposed to increase from 56 to 200R, to maintain
similar plate currents.

Looks like this is actually a later revision.

Just wish they'd documented the changes.

RL