I had built a full wave rectified B+ supply for my HB rig. I used two Microwave Transformers parallel-primary, series secondary worked FB, tested and would put out ~ 0.5 amps at 2200 volts all day long with out breaking a sweat (it did hum a bit while it worked, but then so do I
).
However, while both tranies looked identical they were not. One had ALUMINUM wire on the secondary! (cheap!) It still worked ok, but the only connections I could make were crimp type, I wasn't happy with how that worked out. While I was trying to make a better mechanical connection I broke the wire off, right at the bobbin! (GONE). Aluminum seems to have an issue with fatigue
. Thus rendering this layout NFG...
So...
I added two more rectifier tubes for a full wave set-up, (added two additional filament windings to my HB fillament transformer with extra insulation too). I have a huge beast of a transformer that I pulled out of a commerical MW that was at the dump (2kW unit!). I'll drop that in there with a booster (the alum 2ndry one with the secondary chiselled off and rewound with COPPER as a LV 60-80V) and get about 2800 (or more!) volts out! I thought about using a couple of taps and a switch on the booster to have a high/low power out setup, but decided to just go for the gusto, this is going to be a QRO rig so, no messing about with low power stuff.
Initial tests look like this is going to be more robust than the twins in full wave. I'll have to put the salt-water load back in service and really work it hard to see if it'll survive.
You could easy make a plate supply for a pair of 813s with these guys, they have about the right voltage "out of the box", plus they come with diodes that are rated for them too.