Owen Duffy wrote:

Perhaps a "feeling" that something works better leads to urban myths?

The optimum length of coax in a G5RV feed is zero (metres or feet).

Owen
--
No argument there Owen, When I think back I remember at one time I used
a commercial open wire TV line made by Saxton. It said it was a 300 ohm
line. I suspect it was more like 400-500 line since it was #18
copperweld with a polystyrene spacer about every 2" with a wire spacing
of about 7/8" That seemed to work the best on 75 as I remember.
Go's along with what you have modeled I guess.

I've often thought I would like to lengthen the 300 or 450 line by a
factor of 3 and still use a short length of coax just to get outside the
shack. Is there such a thing as end effect with a feed line when
computing multiple 1/2 wave lengths? Or do I just cut long, short the
far end, and trim it using my MFJ-259. Also will the MFJ-259 be accurate
when used in this manner with a line that is not 50 ohms? I think so,
but not sure.

My only reason for using the G5RV at this QTH is that the 102' length
just fits on my small lot. And I'm sure open wire feed all the way into
a real balanced tuner (Johnson Matchbox etc) would be the best. But then
it's not a "real" G5RV and no more urban myths.

John K1BXI