[Elecraft] OT: Vertical doublets (was: Home made Sigma-GT5 & KRC2 or SGC?)

[Stuart Rohre]

But, with any reasonable commercial tuner out there on the market, You will
not have excess tuner loss nor inefficiency with the 44 foot doublet.

Experiments have not shown ANY heating in  use of Dentron Super (high power)
or Junior (100 watt or less) tuners in several tests using a variety of
doublets or loops.

One has big coils and caps, the other minimal caps and coils to fit a QRP
sized case.  Additional experiments with the 300 watt rated, but compact,
B&W tuner also did not show any heating.  Transceivers were at 100 watts for
the tests.   It was found that a Dentron or B&W did tune up with a more
readily found (higher Q) setting when the internal balun was bypassed and
the tuner was hooked by one foot of coax to an external 4:1 balun made by
Van Gorden.  There was only one foot of coax from tuner coax output to the
balun input.  At the time, the high impedance side of the balun was hooked
to ladder line feed of a 1149 foot circumference loop being tuned to 20m.
The Van Gorden device is obviously a larger inductor than either tuner's
internal balun, and most internal baluns of commercial tuners of that
vintage were voltage baluns.  A current balun is preferred by the literature
on choosing baluns.

Don't let fear of tuner loss keep you from putting up the convenient 44 foot
antenna.
-Stuart
K5KVH