[Elecraft] Twinlead feedline to my K1

[Ron D'Eau Claire]

I'm cornsiderating upon putting up a NB6Zep antenna
( http://home.teleport.com/~nb6z/nb6zep.htm ), and I'm
not sure how to connect the twinlead to my K1, which
has an internal autotuner... 
73/72/oo,

Lloyd, K3ESE

As the web site mentions down near the bottom, the easiest way to
connect the feeder to an "unbalanced" output like your K1 is by using a
"balun" or "balanced to unbalanced" transformer. The NB6Zep is a
conventional "doublet" fed at the center with open wire line. Many Hams
refer to these antennas as dipoles, although "dipole" usually refers to
an antenna that is 1/2 wavelength long.

Using a balun at the transmitter will provide balanced" push-pull"
currents for each side of the feed line. That will minimize radiation
from the feed line, because the r-f fields created by each wire in the
feeder will cancel each other out. That means that virtually all of the
radiation will take place from the horizontal wire up in the clear.

You can buy baluns from many sources and instructions for making your
own are in almost any book on ham antennas. On line check out
http://www.hard-core-dx.com/nordicdx/antenna/feed/4_1balun.html or
http://www.bytemark.com/products/kit_bal1.htm. I got these with a quick
peek with an internet search engine. If you search on "balun" you'll be
inundated with info! Keep in mind that baluns are used in many places,
not just transmitters. You want a "transmitting" balun, not one designed
for television or some other small signal use. With this type of
antenna, the impedance at the balun will vary widely over the various
bands and r-f voltages and currents can be very significant, even at QRP
power levels. 

Be sure to keep the feed line away from objects, especially any metal. A
distance of 2 or 3 times the spacing between the feedline wires is
usually adequate. 

Ron AC7AC
K2 # 1289