Can you tell me how is the transformer built (e.g. secondary over =
primary, or physically separated windings)? Do you see any air gap in =
the lamination?

I am trying to determine whether the secondary is lightly coupled to the =
primary. Taking into account the scope of the equipment, this could have =
been done to limit maximum power transfer onto the secondary.

Tony, I0JX=20

"Mike Knudsen" ha scritto nel messaggio =
...
This may be OT but could apply to some high-voltage transformers that =
supply
hihg-powered TX finals.
=20
Does anyone know why the 4 KV secondary of a medium-sized transformer =
used in
an electrostatic precipitator air cleaner should have a 0.01 uF cap =
across its
secondary? My suppy failed when this cap opened up. Without it, only =
a small
fraction of the voltage was developed across the two diodes and 0.08 =
filter
caps in a voltage-doubler circuit that produces about 8 KV at up to 5 =
mA.
=20
When I replaced it with half the original value, a 0.047 6KV cap from =
an old
color TV parts bin, I got enough DC output to draw a 1/4" arc. But =
when I
paralleld a second such cap, to pretty much equal the original value, =
I got a
3/8" or more arc, and the transformer made buzzing noises like it was =
really
doing some work.
=20
I permenently soldered in the two replacement caps and put the air =
cleaner back
together. It works good as new again. Oh yes, I added a fuse to the =
primary
side, just in case my new caps short out. Odd there wasn't one =
already.
=20
Anyway, I at first thought that shunt cap was just to protect against =
line
spikes, but apparently it tunes a resonance in the secondary winding, =
or
something. Has anyone else encountered such a cap? Obviously a =
dangerous
place for a cap to be, so I can understand this isn't used often. 73, =
Mike K.
=20
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