If your open wire is short, why bother? Replace it with low loss coax, put a
decent common-mode choke at the feedpoint and tune it. Sometimes the effort to
use open wire simply isn't worth it.
Wes N7WS
On 7/17/2018 10:43 AM, Mark Spencer via TowerTalk wrote:
Hi:
I spent some time trying out various wire antennas at the summer cottage and
have more or less settled upon a dipole antenna fed with a short length of open
wire feeder that runs from the antenna feed point to slightly above ground
level, the open wire feeder is in turn connected to a Johnson match box (a
tuner with a balanced line connection), which in turn feeds a coaxial cable
that runs to the radio. The tuner sat on top of a short step ladder during my
tests.
The coaxial cable had various mix 31 and mix 43 ferrite chokes applied. It all
more or less worked as I expected it would on various bands.
Moving forwards I'd like to replace the Johnson Matchbox with an auto tuner.
At this point I'm leaning towards purchasing a suitable Balun from DX
engineering, connecting that to the output of my SGC231 tuner and replacing the
Johnson Match box with the Balun and the auto tuner. I'll have to do some
modelling (to figure out the likely range of feed point impedances for the
dipole antenna at various frequencies) before deciding on what ratio Balun to
buy. I expect I'll install the auto tuner and Balun on top of a wooden pole
perhaps 10 feet or so from the ground.
I am curious if anyone else has done something along these lines and if there
are any issues with doing so ? Any comments would be welcome.
I'd like to move away from using a commercially made trap dipole at that
location. (The appearance, lower weight and wind loading of a simple wire
dipole with a short open wire feeder is attractive to me, plus I need to use a
tuner to match the existing trap dipole.)
73
Mark S
VE7AFZ
mspencer12345@yahoo.ca
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|