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

[JAKidz]

Greetings:

	Any suggestions on the optimum dimensions of a ladderline-fed
Sigma-GT5-like hatted vertical doublet that the KAT100 will tune
efficiently between 10 and 40 m? A Sigma-GT5-like design posted on
Usenet by AB6SJ takes advantage of the availability of aluminum tubing
in 6 foot lengths so it is a bit bigger than the GT-5. 

	W4RNL suggests a 44 foot horizontal doublet fed by ladderline is
an optimal doublet length for 10-40m. It's tempting to turn this doublet
vertical and shorten it with bar hats like the GT-5 if it is efficient.
But at least one antenna guru (whose call I can't find at the moment)
has stated repeatedly that W4RNL's doublet design is very inefficient
because of tuner losses. Who is right? What are the tuner efficiency
tradeoffs of having the structure resonance low, high or mid-frequency?

73,
John, K7JG