Topband: Compromise vertical loading questions

[Charlie Cunningham]

Hi, Bjorn

Well, I can't argue with JC. With my first ever inverted L for 160, I had
similar experiences as did his friend, AA7JV with; submerged radials. In my
case, the inverted L was on the dam of a lake behind my house. Not salt
water, of course, but the lake had been treated with some amount of copper
sulfate to control vegetation growth. I cut perhaps 8  1/4 wave radials of
bare 14 gauge stranded wire and weighted the  ends with bricks. I then used
my canoe to fan the radials over nearly 180 degrees of semi -circle and
submerged them in the lake. Like AA7JV, I could see the driving point
impedance drop and the VSWR bandwidth of the antenna system decrease as I
added radials, reducing the ground losses. One of my earlier QSOs wasn with
Jacky, 3B8CF, on Mauritius around my sunset, but I also worked VK3, VK6, JA
etc. - all with about 400W. So, if you could move that antenna nearer the
water's edge, and submerge that radial in salt water, I expect you might see
some improvement. In any case, GL and have fun!!


73,
Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of JC N4IS
Sent: Wednesday, January 29, 2014 8:39 AM
To: 'Björn SM0MDG'; topband at contesting.com
Subject: Re: Topband: Compromise vertical loading questions

Hi Bjorn

>>>>>
How much I can improve by moving the coil up. What improvement should I
expect if center loading at about 7 meter? How about moving the coil all the
way up to the top loading spokes? Is it worth the effort? (the pole won’t
support much up there).
.>>>>>

 Not much, changing the loading would increase the signal 5-10% , it is
around 1 db, however if you can get close to salt water and get the radials
wet your signal can increase 10db or more. AA7JV can comment better on that,
but close to the water is not good, in the water is unbelievable better.
George used get several  wires tied with a stone and through it into the
water, as you increase the number of the wires, you can see the impedance
changing. You will may lose some of the radials and they need to be
replaced. The radials could be very short and thin but they will work if in
the water.

I can hear you almost every day with the antenna you are using now.

Regards
JC
N4IS





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