[Elecraft] (OT) EFHW Vertical Antenna (Mike Morrow)

[B Hunt]

I've been using a EFHWA vertical for a couple years now as a portable 
antenna for 20, 30 and 40 meters.  It is 33 ft tall and supported by the 
MFJ fiberglass pole.  It uses a small, tapped inductor located about 6 
feet from each end to provide electrical half wave length on 30 and 40 
meters.  The coils are shorted for 20 meters.  The only downside is you 
have to pull the antenna down to change bands.  The matching network is 
a tuned tank using a toroid wound coil and air variable.  The tank 
circuit is matched to 50 ohm coax using a secondary winding with several 
taps.  Full credit goes to N0LX for the design and construction details 
( http://www.n0lx.com/efhwa.html ).

I usually use it with a short (10 ft) counterpoise wire and about 10-15 
ft of coax to the rig. I suppose a bead style choke balun could be used 
on the coax but I've never noticed problems with RF at the tranceiver  I 
typically run 5 - 15 watts into the antenna.

YMMV

Brian
K0DTJ