For sale are new in original box (we have 9 more in sealed outer boxes also), analog power supplies,

5V 6amps w/overload preset at 6.2V +/-0.4V,  12V 2.5A avg 7.5Asurge.

These are perfect for 300B vacuum tube amp filament supplies.

Amps with AC to 300B filaments are junk, you adjust the hum buck, and see the filaments sag or rise at different volumes, and the hum comes and goes.

DC to the filaments would be great if you want to spend a fortune on batteries.  Try a switching power supply and you'll hear the high frequency switching.

These analog supplies work great.  5V powers up to four 300B filaments, and 12V powers 6V preamp tubes with heaters in series, or 12ax7s etc.

price is $39 each (we have another listing of the same titled 300B tube amp DC filament power supplies)

size is about 3x5x8" google their specs

these have dual primary can also run on 230-240V 50Hz...