Jeff Liebermann wrote:

On Fri, 15 Feb 2013 16:12:12 -0500, "Michael A. Terrell"
wrote:

I want a rechargeable battery pack
with built in DC-DC converters for the 90 V plate & 9 V filament
supplies.

Maybe...
http://www.maximintegrated.com/app-notes/index.mvp/id/1751
While the above example can only deliver 1ma, the basic idea should
scale nicely to something with more power.

More general and more interesting:
http://www.maximintegrated.com/app-notes/index.mvp/id/1109

I would be tempted to take a 12v to 117VAC cheapo inverter and modify
the output circuit to produce DC instead of AC.

That would require a lot of filtering to keep hum out of the audio
and harmonics out of the RF.

The feedback should
be adjustable so that the output can be set to 90VDC. The trick is
finding one that includes a schematic.


Where is the fun in that? it's more fun to start with a blank page.
;-)

I want to run at least 100 KHz, but would prefer a higher frequency.
The estimated average current is 10 mA from the datasheets for the
tubes. A torritdial transformer will raditae less noise, be more
efficient and the entorecirccuit should fit a deep drawn box the size
ioof an Altoiods box, or one of the hundred or so NOS bathtub caps with
bad seals I have in the shop. They are easy to open, with a propane or
aceteleyne torch. Melt the solder around the edge, and find the
soldered over vent hole. Shove a dental pic in, and pop it open. The
lazy way is to solder up a box out of scrap PC boards.