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

Richard (Rick) Karlquist richard at karlquist.com
Thu Jul 24 20:06:17 EDT 2014

On 7/24/2014 9:37 AM, Tim Shoppa wrote:
> The data and tests presented in this source:
> http://www.cliftonlaboratories.com/imd_in_broadband_transformers.htm
> 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

At HP, we once had a bad run of Mini Circuits transformers that would
fail if used in a high impedance circuit that had different DC
voltages on the windings.  Turns out MCL left off the "Parylene"
coating on the cores that protected the magnet wire insulation.

Rick Karlquist N6RK

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