Jim:
I have the QRP version of the LDG, and also some MFJ manual tuners, all single
ended.
I feed my 40m diamond loop with 300 ohm twinlead, with no problem. The secret
is to adjust the length of the feed line to get the lowest possible feed
impedance at the shack end. I have about 20 extra feet of 300-ohm twinlead
looping through my garage rafters before dropping down to the operating table.
At that point, put in a 1:1 choke balun, also called a transmission line balun.
Mine is about a dozen bifilar turns of wire on a ferrite rod. I have banana
jacks at one end for the twinlead to plug into, and a female coax fitting at the
other for cable to the LDG.
Now, the tradeoff. As described, this is a one band antenna system, although it
would be ok on the third harmonic, 15m, also. To work other bands, you would
need to vary the line length again, to get the low impedance down to the shack
end. You could make up some twinlead sections and just plug them in like an
extension cord to get the correct length for any band.
Anyway, not a difficult task at all.
72, Bob N6WG
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