On 8/27/2010 2:48 AM, Ian Wade G3NRW wrote:
From: John Smith
Date: Tue, 24 Aug 2010 Time: 13:20:44

You could just pass the coax though a suitable toroid.

Like this:

http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm

Just goes to show you, if you can think of it, most likely, someone else
has already done it.

I would use a core with no air gap (but, if it was all I had, I'd use
one such as the author of the article did.) If you have/like ferrite
material, a FT114-43 (FT114-61, FT114-77, etc.) should work. If you
like iron a T130-2, T130-6, etc. should work. I simply mention these
because the ID would pass over a pl259 with a few turns of thin wire,
larger ID toroids should be fine. I would think you can use whatever
you have which will fit over the connectors you are using on your coax.
Simply wrap the turns on the toroid, pull the connector off the
tuner/rig, slip coax through, reconnect coax.

I just happened to have a T200-6 in a drawer here. So, I wrapped a few
turns on, slipped it on the coax, ran the secondary through the 50ohm
shut, diode/cap, and to a cheap VOM. With ~100w and the coax into a
50ohm dummy load, the reading I get is just reflecting the loss in the
coax from the 95% braid I am using, most likely. With the coax from the
ant, it appears it would be usable from 40 - 2m (bands limited to my
antennas.) This should easily cover 160m to well below 2m. For SHF and
EHF you may wish to choose a torid of differing material.

Thank you for finding and posting that article. It was a fun read!

Regards,
JS