"Antonio Vernucci" wrote in message
...
Measure the supply voltages and compare with the schematic. If they
are all too high, add in a dropping resistor.

Putting a series resistor would degrade the power supply regulation
performance. This may or may not be important, depending on application.

The safest way to proceed would to put a (properly polarized) zener diode
(or a series of several zener diodes, up to getting the required voltage and
dissipation power) in series with the circuit, so that voltage drop gets
(nearly) constant, independently of load variations.

73

Tony I0JX

What about the internal IR losses of the original vacuum tube? The
regulation should be
nearly the same if done right.

Pete