After many frustrating experiences with unwelcome interaction between
various 160 antennas and towers, I am thinking about going back to
basics by removing all the other 160 wires, and shunt feeding the 110
foot tower (which has a number of yagis on it). All else being equal
(such as ground system), are there reasons why a shunt-fed tower would
work differently than a vertical of the same height, on an insulated base ?
73,
Steve, N2IC
_______________________________________________
Topband reflector - topband@contesting.com
Hi Steve and All,
I was writing about my tests a few years ago but maybe it will be useful for
some...
I was using a Half Sloper on 20m high tower with TH6DXX on the top. I was very
satisfied with this antenna and it "gave" me 280 DXCC that time. Anyway I
decided to
check how shunt fed tower will behave...I had relays on wires of sloper so I
was
able to make tests during QSOs in a real time. After more than 30 QSOs with
stations
of a distance above 5000 km I decided to stay with shunt fed system..95 %
correspondents
gave me 1 to 2 S better report when using the tower. I have to add the tower is
only 4m from
my house ( 9m high).
Regarding detuning... I have K9AY about 30m from a tower and I was not very
satisfied with it
so I suspected the tower affects it. I made detuning described by John ON4UN
(LB DXing
fourth edition page7-94 fig.7-135) . I did it for both 80 and 160m so I'm able
to switch
it on TB on and off ( switching to 80m).. the difference is huge , the null at
the back can be worse
even 2 S when the antenna is not detuned.
73 GL
Rys
SP5EWY
_______________________________________________
Topband reflector - topband@contesting.com
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