Topband: Using the K2AV folded counterpoise at VK6VZ - oops

[Steve Ireland]

There is a small correction necessary - see the text highlighted in CAPITALS
below. Unfortunately, living relatively close to the equator, there is very
little DX signal propagation on 160m after sunrise/before sunset (only about
+15 minutes/- 15 minutes) and this seems high angle.

 

-------------------------------------------------------

 

G'day

 

Here is some encouragement for those of you who are thinking of trying the
K2AV folded counterpoise.

 

Back in January my Kenpro KR400 rotator finally gave out after about 18
years of misuse (which included turning a 40-10m homebrewed 2-element quad),
resulting in a total rebuild of the VK6VZ antenna system.  

 

For the last 17 years or so, I've mainly used inverted-vee and inverted-U
type dipole antennas on 160m, as much experimentation with Marconi shortened
vertical and inverted-L antennas had been very disappointing.  The best of
the antennas, a Marconi-T with a 66-foot vertical section over about 30
60-foot to 100- foot radials, had proved relatively ineffective in
comparison to an inverted vee dipole at 90', with the former usually two 'S'
points down on the dipole to stations in Europe and the USA.   

 

Having read about the K2AV folded counterpoise, which I could mount along
one side of the half acre block here, I decided to (once again) try a
Marconi antenna.  With the counterpoise in this position, I put up a 3/8
wave inverted-L antenna with a 100-foot vertical section (the antenna is
100-foot up, 100-foot out, similar to that used by K2AV).

 

So far the results with the 3/8 wave inverted-L (tuned via a series
capacitor to get rid of the inductive reactance) and the folded
counterpoise, fed via K2AV's isolation transformer balun (I bought the
commercial Balun Designs one) have been startling to say the least.   

 

For the first time with a Marconi antenna from this location, I can work
just about anything I can hear with similar reports, the feeder/common mode
isolation is such that I have virtually no pick-up of the humungous amounts
of noise generating devices in the VK6VZ household through which the feeder
passes and the antenna is good on local ground wave signals, high-angle DX
signals right on sunset/sunrise AND ON LOWER ANGLE DX WELL AFTER SUNSET/WELL
BEFORE SUNRISE. 

 

Having a 100-foot rather than a 66 foot vertical section is clearly a big
help in the performance of this antenna - and the only reason I have this
nice large vertical section is because of being able to site the antenna in
a position where it would have been impossible to put down a radial field.

 

The previous 12-year old radial field (hopefully still about 75 per cent
intact) lies about halfway along the horizontal part of the inverted-L
antenna and is probably helping the signal.  However, by itself, it never
worked anything like as good as the folded counterpoise (and its isolation
transformer).  

 

A big 'thank you' goes to Guy K2AV and Jack W0UCE for developing the FCP
system and for their advice in helping me get the antenna system going.  I
owe you blokes a beer!

 

Vy 73

 

Steve, VK6VZ