Question 1:
I am planning on building two dipoles, one 40m and one 30m, on one
feedline. I know I can calculate the length based on the 468/F mHz
formula, and expect a relatively low SWR on an individual basis, at
least enough to protect the radio used to trim it. Does that
formula still hold if you build two dipoles on the same feedline,
i.e., out of 300 Ohm Ribbon cable or 450 ohm ladder line? I know
there is some interaction -- which do you trim first, higher or
lower freq. antenna? I'm asking primarily because I will use an MFJ
on 40, and hope to use a 38special (when delivered) on 30, and need
a fairly predictible SWR expectation to keep the precious smoke in
the finals.
Question 2:
At one point in my life, when I had access to real estate, I used a
"cage" dipole, cut for 80 meters. It mimics a thick conductor, I
think mine was 10" or so diameter. Worked superb, and with a tuner,
worked equally well on all bands. Seemed to provide a little better
effeciency than a single wire dipole.
In any event, over the past 5 years and 6 moves, I've lost my
instructions on how to cut one. Anybody no the factor needed to
convert antenna length based on a "mimiced" thick conductor?
Instructions for a cage dipole would be appreciated, or directions
to same somewhere on the web.
72 es 73 de
Marty, KM7W
____________________________________________________________________
Jackson, Tennessee e-mail: mdwatt@usit.net
http://www.public.usit.net/mdwatt
"The Curmudgeon's Corner"
NorCal - QRP ARCI #7514 - QRP-L #953 - AK/QRP #098 - Grid Sq EM55oq
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