Topband: Common Mode Isolation

Paul Elliott paab at
Wed Dec 28 23:42:58 EST 2005

Bill:  Tom, most seem to recommend ferrites on the outside of coax to reduce
common mode.  Why wouldn't a 1:1 isolation transformer with 2 turns on both
sides of a binocular core do the same thing?


Tom:  It's just easy to do it all in the one unit by using a primary
secondary transformer, so that's what I do.


I am feeding a Ewe with a matching transformer whose primary and secondary
are isolated, and the coax is not grounded at the antenna.  Would placing an
isolation transformer in the coax, near the receiver, and grounding the coax
between the two transformers be useful in reducing the common mode problem?
Is there something better?


73 Paul W5DM

More information about the Topband mailing list