For sale is this good tested 12 to 14V (its the same thing- 12V with vehicle off, 14V with vehicle running)

dynamotor outputs 250VDC at 85 ma.

I can send you pictures of it being tested if you want.

has a common ground, +12 to 14V input, and output about 270VDC under light load 14K is lightest load recommended,

250VDC at 85ma.   A radio expert told me don't run it with no load, and it was made for oil caps up to 5 uF.  With a power supply choke, 5uF oil cap can be plenty-

here's the funny thing- i had a 160W peavey six x 6L6GC amp with 100uF cap, always hummed somewhat even at minimum volume.  I sent to recap it, and only 500V cap i had was 22uF F&T low ESR, that completely removed the hum, 22uF low ESR filtered better than 100uF.  I've been told oil filled caps can be even better at lower uF like 5uF.  The radio expert told me

the spikes from this dynamometer will eventually make cheap cheap chinese electrolytic caps fail, so we are selling this as-is. 

size- about 2 3/4 x 3  x 4 3/4"

battery consumption- 3.4 amps, runs very smoothly