>
> 1 - does anybody know, how good is the wire insulation in MOT
> (varnish)? That is - what temperature does this varnish can face
> without considerable decreasing its life time?
In my experience the varnish is less of a concern than the type of
insulation on the wire. The only insulation between adjacent wires is
that of the wire itself and the quality (read melting point) and
hardness directly affects its integrity. Wire with red insulation on
it is low quality. I once had it on good authority from a transformer
winder that he used it preferentially in power transformers "because
it is easy to solder". After hearing that revelation I began to wind
my own and to this day have wound hundreds for myself and others. I
would not guarantee the use of self-fluxing (red) wire in any
application where it could/would be subject to significant heating
and/or friction (e.g. magnetostriction). Most MOTs I've seen use this
wire. The *only* wire I use in transformers I build is polyesterimide
coated. The supplier I use won't stock self-fluxing wire on principle.
Possibly there is little demand for it as they sell mainly to motor
rewinders.