[Boatanchors] EF Johnson thunderbolt

[Rob Atkinson]

> I also prefer cathode metering.  The Tbolt has separate metering of the control and screen grid current so if you want the actual plate current those can be subtracted from cathode current.
>

Okay, that's what I didn't know.  Thanks Rodger.  Since g1 and g2 are
current metered then Ip can be easily computed from Ik.


>
> My Johnson Desk uses cathode current metering but did not have separate metering for screen current so you had to guess at the potential of each based upon Johnson’s predicted values.  I added a small external screen current meter which solved that problem.  Any high power grid driven tetrode amp should have screen current metering since it provides the best indication of proper tuning and loading.
>
Same with my 4-1000 rig.  I added a screen current meter for the same reason.

Rob
K5UJ