[time-nuts] IMD in Broadband Transformers and be careful with that enamel insulation!

Tim Shoppa tshoppa at gmail.com
Thu Jul 24 12:37:50 EDT 2014

The data and tests presented in this source:


is a great resource on measured large-signal performance of
binocular/toroidal transformers. One factor found that can really degrade
IMD performance it turns out, is not the magnetic material itself, but  but
physical damage to enamel insulation in winding around corners of
unfinished cores.

My large signal usage of BN73-202's aka 287300202's, is that not only do
they make great 160M transformers, I've also been putting them to use in
multi-watt DC-to-DC step up converters! Similar to the Clifton labs test,
in HV step-up usage I usually find the enamel insulation limits and/or
winding-around-corner damage to be a much more prominent limitation on
performance than the magnetics.

Tim N3QE

On Sat, Jul 19, 2014 at 6:09 PM, Attila Kinali <attila at kinali.ch> wrote:

> Hi,
> I'm currently looking at some way of breaking the ground loop between
> several systems. The obvious idea would be to use transformers. I would
> like to have some kind of rule of thumb to guess how much noise such
> a transformer would add. But unfortunately i cannot find any theory
> or measurements of this. Does anyone have some pointers to documents
> on what kind of noise i could expect (type, and strength) and
> what/how strong the non-linear behaviour of transformers would be?
> Thanks in advance
>                         Attila Kinali
> PS: although this started as something with a real application in mind,
> i'm now interested in this as an endavour of its own. So all and any data,
> theory or rule of thumb would be appreciated
> --
> I pity people who can't find laughter or at least some bit of amusement in
> the little doings of the day. I believe I could find something ridiculous
> even in the saddest moment, if necessary. It has nothing to do with being
> superficial. It's a matter of joy in life.
>                         -- Sophie Scholl
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