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Re: Topband: Recent 160m Antenna Questions

Subject: Re: Topband: Recent 160m Antenna Questions
From: Dave Court <>
Date: Tue, 27 Nov 2007 08:58:27 +0000
List-post: <>

Thanks for your comments. Just a few additional remarks.

I noticed an error in my previous email concerning half-sloper
experiments. The last sentence in the second paragraph should have read:
>> "It is possible to add a loading wire to the tower but
>> I didn't have too much joy with that since the loading wire had to
>> follow a similar direction to the wire part of the sloper."

> First you mentioned that you had elevated radials.... that's costing you in
> two ways... first your losing that amount of vertical height and that is 
> important... 

Yes I agree, however radials previously were about 6 laying on the
ground. These had to be removed in summer for grass cutting so thought I
would experiment with elevated radials after reading reports that a
small number of resonant elevated radials tended to equate to a larger
number of the buried/on-ground variety. This is my impression anyway
from various threads on various lists. I was also quite impressed by
reports from the 6Y4A gang - see Actually the radials are
slightly short and I use a series roller-coaster to tune them for
minimum SWR together with the series capacitor in the antenna.

> So there were numerous feedlines. They came down two legs
> of the tower. plus the rotor cable.

Thanks for your views on shunt feeding the tower. Unfortunately as my
tower is a wind-up/tilt-over tower I cannot tape the cables to the legs
of the tower; they have to hang freely. I guess wind movement might be a
problem if the match changes significantly? Also I'd like to know if
anyone has run into problems of electrical and RF connectivity between
sections of such galvanised telescoping wind-up towers.

But in any event it will be interesting to conduct some experiments on
what I have and it would be nice if I were able to use it on 80m as
well. You never know till you try! I'm also considering laying a ground
screen on the grass around the tower of what we call in these islands
chicken wire. Its name is derived from the thin galvanised wire one
would use to make a chicken pen. The screen would extend around 60ft in
two directions from the base of the tower and could be supplemented by a
few buried radials.

Further comments would be welcome on the above and concerning whether
there is any advantage using an extended 3/8 wave inverted L and series
capacitor over a near 1/4 wave inverted L cut for the best match to a 50
ohm feeder.

73s Dave

This Email comes from Dave Court - EI3IO, G3SDL, OZ3SDL
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