Topband: Re:Condx tonight

[Mike Sloan]

Saul, K2XA wrote:

>and finally GU3WHN who popped up at 0407, peaked at a real 599 and
>promptly disappeared.

Thank you, Saul, for the most encouraging report.  

What Saul did not hear was the fact that I could not shake the non-DX
stations who just called and called and were very loud.  I went QRT,
sri. Hi!  Hence my recent posting.  However, a few evenings and mornings
listening have indicated that my intentions will be almost impossible to
achieve. Never mind, I will just get on with it.

I thought it might be of benefit to some on the list to describe in more
detail the present antenna setup here.  I was lucky enough to be
presented with John's, ON4UN's "Low Band DXing" last year and have found
it very interesting.

This will be a strictly low technical explanation as I realise that
there are some exceedingly clever people out there.  Hi!  What I have
attempted is the usual modus operandi here of adaptation according to my
local conditions and restrictions.

The QTH here is 100 meters from the high water mark of the Atlantic
Ocean.  The ground is pure white sand.  

The following conditions prevail:

1.  Ground is classified as "Very poor"

2.  No room for buried radials

3.  Beverages for reception are not considered by ON4UN to be effective
close to the sea.  (Only a Slinky would be possible, in any case)

4.  Operations are on all bands 160m-10m

5.  Only one modest support is practical

Quite recently I had a W3DZZ configured as an Inverted Vee.  With the
winter approaching I decided to add 80m traps to include 160m.  This I
did, using commercial traps by Unadilla/Reyco.  At the same time I took
the opportunity of buying a new 1:1 balun, to include 160m from the same
source.  The antenna was built and was tuned to perfection.  Well, that
is what the analyser indicated......!

Having had a reasonable amount of success with a plain, no radial,
quarter wave end fed sloper a couple of years ago, it occurred to me
that I could turn the now extended W3DZZ around to configure it as a
sloper with an elevated counterpoise.  This I did and the measurements
looked promising. Nothing was mechanically changed from the dipole
configuration.

On further reading of ON4UN's book I came across a description of the BC
Trapper.  The difference between the two is that, in the case of my
setup, an elevated, trapped radial was taken into use.  Further reading
suggested that a symmetrical use of elevated radials is beneficial and a
second trapped radial was installed yesterday.  Furthest DX last night
was UA9YMT on fone.  He was 58 and gave me a 56 report.  I was using
350w pep.

What I appear to have is a cheap, compact 160m antenna which allows me
to rotate my 3el yagi below it.  It has a conventional 1:1 balun and a
coil of RG8 below the feed point as an extra precaution.  Each of the
three "legs" is in the order of 97 feet or 29 meters.  This, of course,
gives a total length of the elevated radials of 194 feet or 58 meters.
It fits my plot with about 20 feet to spare at each end before getting,
at the nearest end, too close to the cottage.  The vertical element
slopes at about 50 to 60 degrees in order to allow the beam to rotate in
the clear. The impedance reads 50 ohms and the matching is 1:1.  Adding
the second elevated radial raised the matched frequency to 1.848 Mhz
with the SWR at 1.4:1 on 1.830 Mhz.  I will fine tune this out later
on.  The elevated radials run East/West and the sloping element runs
some 20 degrees South of West. Feeder is about 60 to 70 meters of mainly
buried RG8.  This is switched by relay between the tribander and the
sloper some 10 meters from the feed point.

The additional bonus of my antenna is that it tunes 160m to 10m,
including the WARC bands.

There is little doubt that the close proximity of the Atlantic has a
dramatic effect on propagation.  Possible improvement might be the
adding of a second top loading wire to move the current more into the
sloping section of the antenna.  I wonder how it models...........?

Well, that's it.  No breach of any copyright anywhere is intended.  Hi! 
Link for graphical details will be found under my callsign at
http://www.qrz.com 

73 de Mike  GU3WHN



--
FAQ on WWW:               http://www.contesting.com/FAQ/topband
Submissions:              topband@contesting.com
Administrative requests:  topband-REQUEST@contesting.com
Problems:                 owner-topband@contesting.com