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50v Filament supply

B

brud

Active Member
I need to test some 50CA-10 vacuum tubes - these have a 50 v filament supply . These are from a Luxman SQ38FD amplifier .

i have an eTracer tibe tester that i can use however i need to supply a external 50 v filament supply .

what is the easiest way to do this?

? if i remove all the output tubes from the Luxman is this ok for the output transformers ??
I will then have a 100volt supply from the transformer !

i do not have a benchtop supply of 50v

?? Can i run my variac at 50v for the filament supply to the one tube under test in the tibe tester .

cheers and thanks in anticipation for a solution
 
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if its done like the schematic indicates, there is no winding on the transformer for those. It appears they run straight across the power line.

If you have an isolation transformer, that plus the variac will do. I just wouldn't want to tie it straight to the line in case that would be an issue with the etracer. Failing that, have any solid state gear or a pair of reasonably stout filament transformers? SS gear often has AC in that general range, or a pair of stout filament trafos wired back to back will serve as an inefficient but effective iso transformer. That plus the variac will get you what you need.
 
gadget73 said:
if its done like the schematic indicates, there is no winding on the transformer for those. It appears they run straight across the power line.

If you have an isolation transformer, that plus the variac will do. I just wouldn't want to tie it straight to the line in case that would be an issue with the etracer. Failing that, have any solid state gear or a pair of reasonably stout filament transformers? SS gear often has AC in that general range, or a pair of stout filament trafos wired back to back will serve as an inefficient but effective iso transformer. That plus the variac will get you what you need.
Click to expand...

That's exactly how I'd do it (iso tx plus variac). And the idea of using a transformer from an ss amp plus the variac is also great.

Another idea I can think of is if is if you happen to own another tube tester, it could be jerry rigged to provide the voltage.
 
Not a viable solution. You need to feed it 55vdv to get 50vdc out of it. If you had 55vdc you would just use that.
 
It was designed for a daisy chain of tubes to add up to 120volts so if you have one more of them and two 12voltntubes that need the same current you can put the heaters in series. Or find a tx out of a solid state amp that has two 24v windings or a center tapped 48v.
 
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