[TowerTalk] Auto tuners, Baluns and open wire feeders

[jimlux]

On 7/17/18 7:37 PM, Grant Saviers wrote:
> Just my 0.02.  Count me as a fan of fan dipoles as the way to go.

So far, in terms of ease and non weird patterns (80m dipole on 15m has a 
lot of lobes) is a multiband parallel dipole (like a DX-CC, with 
parallel wires spaced 6" apart) fed by a tuner in the shack.  Normally 
the fan or multiband is a pain to adjust because of the element 
interactions. You shorten or lengthen one dipole and the resonance 
changes on all the other bands.

However, it doesn't change by much. Maybe the 20m resonance goes to 13.9 
MHz.

Well, that's not a huge impedance change, maybe from a nominal 70 ohms 
to something like 68-2j.  that kind of mismatch isn't going to cause 
enormous losses in your coax like you'd see with driving a 40m dipole on 
20m (where the Z is something like 2200 ohms) or driving a 20m dipole on 
40m (where the Z is 14-600j)

So you build the dipole with lengths that are *about* right, hang it in 
the air, with an appropriate choke at the feedpoint, run coax, and be happy.