Hello the Group:
I accept the fact that a few rocks will be thrown, but allow me to describe
my source for a 5 Kw plate transformer. About in 1996 I started building
large Tesla Coils, in the 15 Kw input range. The ideal source for high
voltage power was a Pole transformer, run backwards. Over the years, I
obtained 4 in the 5-25 Kw range. These had a 14,400 VAC primary, with a
120/240 VAC secondary on the smaller ones, with a 22,600 VAC primary and a
120/240VAC secondary on the biggest one. The Tesla Coils worked well,
stopping traffic during each run at night, with 12-16 foot arcs !
OK, so I lost interest in my 61 KHz, 15 Kw Tesla coil work. Sold the main
system and still had 3 pole transformers. Amateur Radio called again, and
after getting active I decided to build a Linear. On the shelf were four
3-400Z tubes I got for free new in the box in 1969, so I designed an amp
around those tubes, which can be referenced as a low cost alternative.
Where to get a decent plate transformer became a real issue for me. The
shed had those two 5 Kw 14,400 to 240 VAC pole transformers, so I took a
closer look. Actually, they were both wound with two 7,200 VAC primary
windings and the standard 120/240 VAC output for residential use. A switch
allowed selecting primary series or parallel connections, at the
descrrestion of the power company who purchased the pole transformer. OK, I
paid $45 for these puppies, so I pulled it out of the can, let the oil
(NON-PCP) drain for a month and then started to modify this transformer.
The unit I had decided to work on was wound in a beautiful manner. With the
two 7,200 VAC windings on the outside, I simply cut off one layer at a time
from each winding. Sounds crazy, but it was extremely easy to do! I went
layer by layer, then would inject 10 VAC into the 240 VAC "Secondary" and
extrapolate the present AC output. I paralleled the two original 7,200 VAC
windings to provide the current I needed. I did check the wire size and
found I would easily be able to supply the required current, based on 500
CM/amp. Good enough for a 50% duty cycle.
The finished plate supply provided 2850 VDC under no load and 2700 VDC under
a 1300 watt output load, around 2,000 watts input. Ah, 168 mfd in the
filter cap. I used a boost/buck transformer in the circuit, the primary of
the boost/buck was fed by a autotransformer. So, it was easy to dial in the
planned for plate voltage. 1N5408 diodes and a step start allowed things to
If anyone wants pictures and further details, just ask. Pole transformers
are really low cost, if you have friend at the local electrical co-op!
This is NOT an approach for the beginner, consider this a marginal set of
details----Just some comments to consider---
Just another alternative,
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