On Sat,8/6/2016 7:58 PM, rick jones via Elecraft wrote:
Ok sorry for not providing enough info! Consider this scenario: I have a
portable vertical with 4 counterpoise wires that is resonant on 20. Lets say I
want to tune the antenna up on 40.
Rick,
You're asking the wrong questions. The best solution to your problem
involves changing the antenna! When you want to operate on 40 (or 30),
improvise a mechanical solution to make the antenna longer. Study the
ARRL Antenna Book and the ARRL Handbook so that you better understand
how antennas work. Another fundamental principle -- the smaller the
coax, the greater the loss. The SHORTER the coax, the less the loss.
RG58 is BAD, because it's small. RG8X is better, because it's bigger.
RG8 is even better, because it's even bigger.
And, as Wayne has observed, we don't need "built" or "purchased"
antennas for portable/backpacking use. Throw a wire into a tree, or
support it vertically, connect it to the center conductor of the coax
connector at the output of the rig. Try to get it close to a quarter
wave, but don't lose sleep if it isn't real close. Connect one or more
wires to the chassis of the rig to act as a counterpoise. Don't know
what that word means? Look in the ARRL Handbook. Try to make those wires
close to a quarter wave. Don't lose sleep if they aren't. Fire up the
radio, activate the tuner, make it tune, and call CQ. We don't need no
stinkin' coax!
The great small club of which I was a member in Chicago hosted a QRP
night every year. We set up in a "forest preserve" -- local park -- and
everyone brought their rig and antennas. I brought a K2, battery, a
couple of lengths of #18 wire, and a telescoping fiberglass pole. I
taped one wire to the pole, shoved it into space between the parts of a
picnic table so that it was somewhere between horizontal and vertical,
and connected it to the center of the coax connector on the K2. I
connected another length of wire to the chassis, and laid it on some
weeds. I fired up on 30M and made a half dozen QSOs, AND broke a pileup
from a station in the Caribbean.
73, Jim K9YC
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