Quote:
Originally Posted by Reece
having a 12V heater and made to be soldered in. Most of the subminis I've run across have low voltage filaments.
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It's 6.3V @ 150ma, though I suspect that current rating is an upper limit spec. And that the tube would draw a little less off a true 6.3V source. I decided that this tube heater looked a little too bright, so I paralleled a 1K resistor with it to drain off about 6.3ma of the 150ma series heater string current. So the tube heater looks closer to the normal orange color.
I haven't seen any 12V heater subminis, though I have several with 26V heaters. Not sure, but maybe aircraft had 26V power. 12V would make sense for mobile equipment in cars, but wiring a pair of 6.3V heater tubes of the same current demand would get you there. These are the indirectly heated cathodes
The filament submini tubes run at a volt or two. I haven't messed much with those, they tend to be microphonic.