Folks,
I've used home-brewed and commercial "QRO" ferrite choke 'baluns' before.
With QRO and hi-SWR, they get warm, sometimes hot to the touch: I guess that's
the result of choking off the power on the outside of the coax and/or
saturating the ferrite. With QROo. & extended cooking time, I expect the
ferrite denatures and they cease choking anything.
Somewhere on the web*, I've read that air-core chokes are better: abt 6 inches
of coiled coax wound neatly as a single layer (NOT bundled) on abt 4 inch
diameter PVC pipe, or something like that. Theory is that the air core won't
saturate. Best of all, they're practically free.
Anyone more knowledgeable/experienced than me have views either way? Do
air-core chokes work OK on 160? How many turns & what diameter work best??
73,
Gary
ON/G4iFB
* I can't remember where - maybe in W4RNL's collection of articles at
http://www.cebik.com/radio.html ?
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