So it seems like I need to wire up the heater winding to four 6l6s and 6 12ax7s then measure for a voltage drop to see if the transformer can handle the load. If not, a supplementary 6.3v transformer will be used for the preamp's heaters. How would I adapt the power supply to compensate for the 370 - 0 winding, instead of the 420v center tapped winding of the fender?
Ive got the Duncan Amps PSU designer application but I cant figure out how to add components or change some of the things.
Way to test current rating of a power transformer?
Moderators: pompeiisneaks, Colossal
Re: Way to test current rating of a power transformer?
Why worry about guessing in this case? Guessing is fine when you have a really old PT and you have no other way of finding the info. But in this case, there probably is more accurate info to be got from looking at the schematic. A Deuce is not a really old amp - and PV is still making amps. So the schematic probably exists somewhere.
A 6L6 draws 0.9A on the heater.
If you put 4 x 6L6 in parallel, that is 3.6A @ 6.3VAC.
If you put 4 x 6L6 in series that is 0.9A @ 25.2VAC.
I don't have the deuce VT schematic, so I don't know how they wired the heaters. But in other PV amps, heaters are wired in series, which would suggest it could be wired in series. In which case they will have rigged up a DC supply for the heaters. So if you are figuring out the heater winding spec, you'd need to make an allowance for the voltage dropped through the rectifying diodes (0.6V each) plus any voltage dropped through any resistance in the heater supply, because you won't want to rig up the output with too much DC voltage (if the tubes do happen to be wired in series, which they may or may not be). JM2CW
A 6L6 draws 0.9A on the heater.
If you put 4 x 6L6 in parallel, that is 3.6A @ 6.3VAC.
If you put 4 x 6L6 in series that is 0.9A @ 25.2VAC.
I don't have the deuce VT schematic, so I don't know how they wired the heaters. But in other PV amps, heaters are wired in series, which would suggest it could be wired in series. In which case they will have rigged up a DC supply for the heaters. So if you are figuring out the heater winding spec, you'd need to make an allowance for the voltage dropped through the rectifying diodes (0.6V each) plus any voltage dropped through any resistance in the heater supply, because you won't want to rig up the output with too much DC voltage (if the tubes do happen to be wired in series, which they may or may not be). JM2CW
Re: Way to test current rating of a power transformer?
The heaters are wired with 6.3AC in parallel with one side to ground. The way I interpreted that excerpt was that for heater current, since the resistance is so minimal you have to measure the diameter of the wire used in the winding itself, or to measure for a significant voltage drop under the load you plan to use.
Re: Way to test current rating of a power transformer?
I reposted it into the files section a while back Cliff.Cliff Schecht wrote:This one is what I was referring to. I couldn't find the damned thing in my bookmarks or with a search..Firestorm wrote:Is it this one?
http://www.diytube.com/phpBB2/viewtopic ... 65&start=7
https://tubeamparchive.com/viewtopic.php?t=13747
Should be able to do a search under dumpster iron.
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