The 70V windings could be put in series with the 340V winding.
What did this come out of? In any case it is likely that the "0.1A" etc is _AC_ not DC.
340V+70V+70V = 480V AC.
Times 1.4 is 672V DC(!!).
The "0.1A"is probably 0.062A DC.
This leads to an amplifier with 21K CT OT, of around 20 Watts audio output.
Note that because you have a *single* winding, a full-tube rectifier is impractical. Good utilization of a single winding means a FOUR-diode plan with three separate cathodes. The voltage is high enuff that the few split-cathode twin rects are at/past limits. This leads to three bottles and three separate heater windings, in addition to your amplifier heaters.
There is a tube/Silicon diode bridge which will work and gives roughly what Paul says (never know with hollow rectifiers).
As you and Paul say, just the 340V winding gives up to 476V DC. Taking 0.062A DC current this leads to a 15K load and around 15 Watts audio output. This again is a fairly unreasonable design; special parts and poor use of tubes. You *could* run two 6L6 near 60mA total and 15 Watts output, but where do you find a 15K (or 12K-20K) OT? Maybe a Hammond 125E (not ESE), but the bass response is liable to be poor, because this "universal" (like any OT) is wound for best response at lower impedance. The hi-Z connection saves your butt when fixing a dead radio so it "plays", but may be lame worked as a stage-amp at high levels.
Perhaps the best is a 2-6V6 amp with the usual hollow rectifier plus two 1N4007 (400V DC) and the usual DeLuxe OT. This may draw more than 0.062A (more like 0.090A) but the un-used 70V windings and way-underloaded 6V winding represents a lot of surplus capacity which allows a little more from the 340V winding.
The real problem is "most" of the rated power is in turns you won't use:
340V @ 0.1A = 34VA
70V @ 0.3A = 21VA
6.3V @ 6.6A = 41VA
A 34VA DC power amp will be 2*6V6, 2*EL84, 2*6L6.. 12VA at most. So 3/4 of the 6.3V is just dead weight.
The 70V windings are inconvenient for tube Power amplifiers, more dead weight.
I guess you end up with 44VA of good load, on a 96VA lump. Half waste, but a lump in the hand is a dang sight cheaper than shipping a more-appropriate lump to you. If your roadies don't complain, that is.
Actually there may be a happy set-up. However I experimented with the idea for a while and abandoned it. One 6550/KT88 can be worked single-ended near 650V and 60mA with a 10K load and deliver around 15 Watts (13W clean, 17W guitar-clean). However the 125ESE at 10K drops-off the bottom octave of guitar. And the screen really wants to be nearer 300V (else G1 bias and drive get absurd), which leads to multiple supplies. Ah, you need multiple supplies because feeding 600V to your 12AX7 is rude and accident-prone. It gets complicated fast.
Put two dozen 12AU7 together and build an organ.
Or a 44-stage distorter.
Topic: What to do with this PT? (Read 4357 times)