[Elecraft] Balun for KX1 - doublet combo?

[Ron D'Eau Claire]

Frank, PA4N asked:

In the meantime I've bought and assembled a KX1 and am now thinking about 
which antenne should accompany it on my upcoming holiday to the Alps... I'm 
considering buying one of those DK9SQ telescopic masts (as soon as I've got 
a definitive answer about the mast being RF absorbent or not; I want to be 
able to use it to put up a vertical too) so I can put up a doublet antenna 
in inverted vee mode. I don't like the 3 dB loss from 10 meters (that's 33' 
for you non-metric people out there) of lightweight RG174 coax, so I'm 
contemplating feeding with open wire.

Now the big question: how to connect the symmetric open wire feeders to the 
KX1?
a) Don't bother; just plug one wire into the hot side and connect the other 
side to the case
b) Use a balun
c) Something else.

If b), then what configuration would you use? How small a toroid would keep 
up with the torturing that it might get in such a high SWR environment?...

---------------------------------

Welcome to the gang Frank! 

I'd use choice a.

If you use a balun, the size of the toroid isn't the issue. It's how many of
those 2 to 4 watts from your KX1 you want to throw away as heat. The smaller
the core, the more obvious the losses because it'll get hot to the touch,
but the losses are still there even with a big core. 

Of course, on some bands the balun may be okay.

A couple of options you might consider. Use RG58 coax (or even RG174 if you
absolutely, definitely must have the small stuff) and feed a double-dipole
cut to length. You can make it out of 300 ohm TV "twin lead", some rotator
cable or even zip cord. You make one half of the cord 66 feet long and the
other half 33 feet long. That covers 40 and 20 meters. On the shorter
length, let the last couple of feed dangle down to provide good RF
insulation and decoupling from the ends and the longer radiator. If you must
include 30 meters, consider a 1/4 wave "radial" on the ground and tie the
feeder together and load it as a vertical on that band with the dipole
acting as a "top loading". 

Ron AC7AC