finally a little progress...

[Ed/KB1HYS]

One hand in pocket!
I got the plate power supply up and running for my HB 4-250rig.
Choke input, filtering is a bit light with 7H and 8Uf but I may add a second section later.
Its a pair of 2200v MOT's wired up as a 2200-0-2200 CT.  Rectified by a pair of 866's. filament trany (for the 4-250 and 866's) and a 6.3v windingis rewound on another MOT core.  All built on a 3/4 plywood base with 4in bb casters.

2kV @ ~500mA under test into a 4kohm load, which matches my figures (well close enough anyway) and could put out a lot more current I think, limited only by the 866's and the supply circuit. 

Plenty of power should I ever "upgrade" to a pair or 4-400 or what ever.

I'm figuring to pull 400v for the screen from a tap off of the bleeder resistor.

Now to work up a grid bias supply .

Now to put in some provisions for interlocks and a timer.

[N3DRB The Derb]

sounds good Ed.  I am starting up my own HB project - impatient to get going so I went on a ebay buying spree. Stuff should start arriving today. I still need a lot of iron. I guess as of right now I have 200 bucks invested.

I wanted a 2 holer but I think I'm only going to get one. as of now, I only have 110 watts of audio to play with. That may change for the better, if it does, then we are lookin at 300 watt carrier instead of 150. 

I'm also buying the wire I need to put my antenna back up today, and putting the rack on wheels. Gonn be hard but wifey is going to help me lifting and with teh drillage and blastage. ugh, 16 holes. 

it will be so nice to just roll it around tho.

[Ed/KB1HYS]

The wheels are a must. These things seem to get heavier with every year that passes. Take it easy and do what you can. 

I was thinking of a two-holer, but right now I've only got the one tube. This thing is on a 19x24 inch base so I'll have room to spare I think.  I am making the chassis big enough for a second tube&socket should I ever decide to.

[N3DRB The Derb]

my tubes are (a lot) smaller - I might just get the second hole punched out now and just leave it there. But that would be kinda weird.

I think I'll just go for one final and build it that way. with the right plate iron I'll still get 200 watts out. thats enough for now.

I think. 

the little devil on my shoulder is telling me to get both holes punched out and just run small plate voltage to them until I get a bigger mod xfmr.  I want more power....more.....drool 

I gotz 4 tubes.....2 with 2 kv =  a maul.

[Ed/KB1HYS]

If you've gotten everything 'cept iron, I'd do it up as 2 x 2 and just run them conservatively until you get some big iron.  I'd figure that replacing the tranny with something bigger would be a lot easier if you built the rig with the eventual HV in mind and then just swapped the tranny sometime later.  If you never find a new xformer, well then you'll have a real Battleship boatanchor there that will last forever!

[Opcom]

glad to hear this. The apprentice will want to use the same PS scheme to operate the four-811 tesla coil. It's being built in a 4-FT rack that has a sloped top section. He left tonight with a dual 15A variac and two rackmount PS chassis having plenty of 4-pin ceramic sockets, as well as some uni-strut! He already has the 866's.

Once the new coil is hissing away, it'll be modulated so we can listen to music.. We did not have this magic size of plate transformer, only some larger and smaller. But he has lots of MOTs left over from previous tesla experiments. I'm grateful you put the truth to the method.

[Ed/KB1HYS]

Well, I can't claim the idea was original, but it does work. 

Use care with the choice of MOT's  two I thought were Identical turned out not to be. one has Aluminum wire on the secondary. Very hard to solder to that!

in my case I lifted the lead off of the core and have them isolated on a wood base, I think if I had phased the primaries differently I could have just bolted them together and used the core leads as my CT which would have been much better.

I'f I was adventurous, I'd try the scheme with a couple of Neon Sign Trannies and see what I could do with 30kv!