turning transformer into LF choke

Microwave Oven Transformers (MOT's)

- have a high voltage secondary winding,
rated at around 2800V and .5A,
with resistance well under 150 ohm

- have the sides of the I-section of the core line-welded
to the E-section, not meshed with it, and therefore
relatively easy to split off by using a hack saw on one side.

I long wanted to experiment with turning transformers
into LF chokes for vacuum tube power supplies.


MOT's seem particularly apt and available candidates,
but the following considerations should apply to any transformer.

--------------------------------------------------------------------

I plan on

- putting all windings in series (in-phase of course)

- splitting off I-sections to reduce saturation as DC flows

- adding magnetic shielding in the form of a thick ferrous alloy
shield belt
coplananar with the winding, and extending well beyond its height.

--------------------------------------------------------------------

Things I have doubts about:

- should the core I-section be removed
or left in place but insulated and distanced
from the E-section? (I saw both options mentioned)

- is the core supposed to be insulated from the chassis?
and from the magnetic shield?

- is there an advantage in point-grounding core and shield
to chassis, as opposed to bonding them more broadly?

- how do I close the loop in a ferrous alloy mag shield belt?
bolt it?
spot weld it?
line weld it?
or are overlapping layers enough?

--------------------------------------------------------------------

I hope in wise advice.

[x-posted onto sci.electronics.design & rec.radio.amateur.boatanchors]
.

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