Reason I'm asking this is that I have a general-coverage HF receiver
which originally came with an external power supply, which was long
missing by the time I acquired it. I can get close enough to the top
B+ voltage by using a 120:220 voltage adapter transformer and a silicon
full-wave bridge rectifier. (Everything in the AES catalog either has
an insufficient current rating, or is criminally expensive. Even a
low-end adapter transformer can handle 100 VA, which is plenty enough
for my purposes and costs a fraction as much as an official "B+"
transformer. Getting the "A" and "C" voltages is no problem so I'm
not discussing them here.)
 Hammarlund SP-400-X in case you're interested.
 Yes, I've put out feelers for an original replacement, but haven't
had any luck.
 350 volts. I should be able to get 300 volts out of the
arrangement above, and when the set is operated from a (large!)
stack of B batteries, it made do with a B+ of 225v. So I think it
should be plenty happy with 300.
I have the schematic for the original supply, which uses a multi-stage
filter and draws out successively lower B voltages behind subsequent
chokes. I plan on substituting power resistors for these chokes, and
it would be nice to get a rough idea of what values I should initially
try. I suppose I am going to have to experiment a bit, but it even a
ballpark figure will help give me an idea of what values I should have
handy before I start experimenting.
"Rats and roaches live by competition under the laws of supply and
demand; it is the privilege of human beings to live under the laws of
justice and mercy." -- Wendell Berry