Success with 6 MOT power supply

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Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Hhchicken1-at-aol-dot-com>

Hi everyone,

Just tested my new 13kV (measured) 6 mot "stack" with great success.  I made 
it by screwing the transformers, chosen for primary-core and secondary-core 
clearance, in two rows of three onto an 8mm acrylic baseboard, which was then 
screwed onto 13mm plywood for added strength - this thing weighs 65kg (nearly 
10 stone!)  I screwed two shelf brackets to the top of the baseboard, and 
then attached a piece of broom-handle to the tops of these to lift the beast 
by. (See http://hot-streamer-dot-com/temp/6MOTguts.jpg)  Although this is 
slightly wobbly it seems to do the job.
I then lifted the whole thing into a plastic storage box, as used for toys, 
clothes etc and filled it with Shell transformer oil.  I think it's quite 
important to use good quality clear insulating oil... my previous attempt was 
similar, using 4 MOTs but I filled it with cheap motor oil, and it only gave 
half the 8000V output it should have - I haven't yet done an autopsy on those 
MOTs but I think the oil may have dissolved some of the insulating paper etc. 
 The plastic box cannot support the full weight on its own (at least it bends 
alarmingly when I try to lift it, and I used the strongest-looking box I 
could find)  so I made a simple trolley with a large piece of plywood and 
some casters, and the box now rests on that.
As you can see in http://hot-streamer-dot-com/temp/6MOTwiring.jpg all the 
primaries are brought up out of the tank onto a board with terminal blocks.  
This makes it much easier to phase the MOTs!  I phased them by applying 12vac 
to each primary at a time and measuring the output voltage.  On top of this 
board there is another which acts as a lid to make it look neat and keep out 
any splashes of oil etc.  (http://hot-streamer-dot-com/temp/6MOTlid.jpg)  Since 
the photos I've added nut-and-bolt style connections for the secondary side 
(the red "ears") and primary side (on a piece of yellow acrylic that comes 
off the side of the board, not shown).

For ballasting, so far I've used a single large MOT for 2.5 kVA (measured).  
I hope to go for capacitative like Greg once I can collect 20 microwave caps!

Thanks to Tim Johnson and everyone else for hints!  This supply should be 
perfect for my big 4" twin system once I've built a gap and primaries for it.

Henry Hallam