I've always had to have pretty close to exactly 50ft of coax on a g5rv. It just
doesn't like less or even more. I've found a 4 to 1 balun works better than the
choke also.
Tom
Tom Brennan KD5VIJ, CCC-A/SLP
web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html