wrote in message
...
In the 1KD-5 amp there is a RCA jack in the Fil centertap line just
below the Bias Zener..The jack has a shorting plug ...Nothing in the
manual ,what is it`s purpose? Thanks Harold

I'm not familiar with this AMP, but in the "olden days" cathode current
was often measured by inserting an ammeter (OK, a milliammeter) in the
filament (it is the cathode) transformer's center tap to ground. (the
shorting plug provided current path when the meter was not in the circuit)
Isn't that how this 3-500Z works too?

Old Chief Lynn, W7LTQ