Tom, if you've connected the ladder line directly to the rg8 or whatever you're
using, you need a choke.  Get a 5 or 6in piece of some sort of plastic pipe and
wrap ten or so turns of the rg8 around it very neatly and tape it into place.  A
transformer choke doesn't work for this but my guess is that will take care of
your problem.  The idea with moving the ladder line is to keep it away from
metal.  Whether you're using 300 or 450 ohm the impedance changes when its
around metal, particular if it gets wet.

Tom


Tom Brennan  KD5VIJ, CCC-A/SLP
web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html