Hi Frank,

thankyou for your reply. I already have a Maplin 240-120V
autotransformer which should do the job nicely. The radio has been
somewhat hacked around with and did come with a heavy and ugly UK
transformer wired as an auto-transformer. It is now removed and will be
used in a future valve based project.

From the poor schematic which I have the secondary goes into a
semiconductor diode voltage doubler. There is then some kind of
resistive chain which I assume generates the voltages for the screens of
the valves. I really need a clear set of schematics to see what values
should be found.

The valve heater voltage part of the schematic is a mystery. The valves
are 4 x 6.3V and 1 x 12.6V, but the schematic suggests a different line
up of 2 x 6.3V and 3 x 12.6V. The valve ids are not readable on the
schematic. Perhaps the schematic was from a mk1, although it is supposed
to be from a mk2.

I have now removed all the components which make up the voltage doubler
and the main triple capacitor is now isolated. I will try to reform it
(from a variable DC supply) and check that it is still working. The
resistors in the chain are clearly not originals. They may have been
changed when the auto-transformer was added.

73

--Gary (M1GRY)