Antonio Vernucci wrote:
If the plate supply has it's own power supply with a separate power
transformer or winding the meter can be placed in the negative lead of
the power supply. Be sure to place the meter outside of any bleeder
resistors so you don't measure the bleeder current.

Thanks for your suggestion, but in my initial message I had mentioned
that my power supply is structured in such a way not to permit measuring
plate current on the negative lead as it would otherwise be normal to do.

As a matter of fact the low-voltage supply is part of the high-voltage
supply; they are not separate. Therefore the current flowing in the
negative lead is the sum of the currents of the two supplies, and it is
then not possible to isolate the plate current of the final tube.

Unfortunately no alternative to measuring it on the high-voltage lead.

73

Tony I0JX

Most good panel meters (Triplet, etc) 2" or larger in diameter in thick
Bakelite cases having glass windows are probably insulated well enough
to safely be used in the high voltage side up to at least 1kv (or more).
I wouldn't try it with a cheap imported meter in a thin plastic case
and a plastic window. Back in the days when REAL transmitters were
housed in relay rack cabinets it was the norm to put an ammeter in the
HV lead. Note that trying to switch a single meter between grid,
screen, plate, and HV readings (meter is used as a voltmeter and reads
voltage across shunts for current) gets tricky, a WELL insulated switch
is required with good isolation between selections! Using every other
position of a rotary switch and yanking out the unused contacts might
have been common.