More on
K9AY
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Basics
General
info on the K9AY loop
Performance
Listening test and other observations
Homemade
How to make your own K9AY
Grounding
The importance of good ground
Wires
How to place wires best
Remote
Remote control
of the KPAY |
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K9AY
compared with Beverages
From 20 to 27 September I was guest in Wilhelm Herbst's house near
Fjerritslev in northern Jutland, Denmark. Wilhelm bought an old
farmhouse up there in the middle of nowhere. And he converted the
farmhouse into a DX-receiving station. On an area covering 4.4 hectars
he constructed a lot of antennas.
Apart from some longwires (25 and 44 meters, a 6 m Vertical) there
are the following Beverage antennas:
150° 160m
180° 140m
195° 160m
210° 160m
220° 120m
230° 90m, in winter up to 290m when the
neighbouring
farmers don't need the fields
245° 80m, in winter 270m
260° 80m
270° 75m
280° 75m, in winter 250m
290° 80m
300° 90m
315° 240m
330° 175m
345° 330m
0° 330m
OK, in northern Finland or Sweden an antenna of 80m is not regarded
as a Beverage antenna, but don't let us be more Catholic than the
Pope. ;-)
All antennas are supported either by bamboosticks or by tomato-sticks,
height about 1.5m, the antennas are grounded via a resistor at the
end.
Anyway, a nice selection of antennas to choose from, and Wilhelm
rents out his home as a "DX-Hotel". He has 3 guestrooms and space
for 3 DXers to listen. Accomodation is cheap, in summer it's 90
DKK (less than 11 US$) per day, in winter it's 120 DKK. Interested?
Contact Wilhelm Herbst, Husbyvej 183, DK-9690 Fjerritslev for more
information.
I had my Wellbrook K9AY with me to compare the performance
of this antenna in relation to the Beverage farm.
The Wellbrook antenna provides a cardioid reception pattern with
up to 30dB front-to-back ratio over a very large bandwidth. The
antenna uses two Delta Loops with a reversible beam direction to
provide a 360 degree coverage.
A unique feature of the K9AY, is the Remote Controlled Variable
Termination. This allows the user to optimise the null during changes
in the arrival angle of interfering signals and provides a considerable
improvement in reception quality.
The K9AY is specifically designed to simplify the construction of
this Loop antenna. The K9AY comprises of two assemblies: Antenna
Control Unit, and an Antenna Head Unit.
The unique feature of the K9AY is the constant high front to back
ratio over a very large bandwidth. The K9AY is probably the only
medium size passive antenna that can provide a significant improvement
to medium and long wave reception.
The antenna simply requires up to two 25m wire Loops. A single 8m
vertical support is required such as a tree. However, it is important
that the antenna is erected away from buildings and sources of interference.
The K9AY only requires an area of 9m x 9m to complete the erection.
Thus, it will fit into most gardens.
To erect the loops I had my Spieth-mast with me. That's a
telescopic fiberglass mast, fully erected 10m high, collapsed a
little bit over a meter long and about 1.5 kg of weight. For earthing
I used a 1m long copperpipe, the earth was rather wet, so that seemeed
to be enough. On sandy soil, rock or under other poor earthing conditions
you may use a counterpoise instead. Both loops had a length of 20
meters. My fault that I did not take more with me, I think a little
bit more wire would have given better signals.
Construction was rather simple. First I hammered a broom-stick into
the soil. Then I connected both loops at about 7m height at the
mast. Then I erected the mast and putted it over the broom-stick.
Then I used 4 tomatosticks to fix the loops around the center mast.
That proofed to be a bad solution. Next day I went to Fjerritslev
in order to buy 4 tent pegs instead. I couldn't find any, so I bought
4 Kebabspits and a Nylonrope. With that I could easily fix the antenna.
Of course the Spieth-mast bended like a bow, but that's pretty normal
and just an aesthetic problem. The mast sometimes tends to collapse
under windy conditions, so I fixed the elements with a bit of force.
No good idea: That turned out to be really bomb-proof when I dismantled
the antenna after a week and there was a lot of swearing and four-letter
words until the mast was fully collpsed. :-) Better use a bit of
tape to fix the elements.
Setting up the antenna took me about 40 minutes from unpacking till
the antenna was up. Another 20 minutes to run all the cables through
the house to the antenna head. All in all less than an hour and
I was ready to listen.
Now to the results. My main interest is MW from Canada and
USA, and there the K9AY was inferior compared with the Beverage-antennas.
In about 80% of all cases the Beverage had a louder signal with
absolutely no background noise. In 10% of the cases both where on
par and the rest the K9AY had the edge. Mostly in cases where european
splatter was strong, like KNR Greenland on 650 kHz. But the hammering
signals of CHVO 560, VOCM 590, VOWR 800 or CJYQ 930 were more impressive
on the Beverages. S-meter pegged to S9+20 dB is an impressive show!
Nothing can top this.
But when I compared the K9AY to the two longwires there were worlds
among these antennas. The K9AY had always the edge (valid for SW
stations too). Compared to the longwires the K9AY was much more
immune against any kind of noise. Even in this quiet surrounding
this was an issue. The more in an noise-infested surrounding!
When listening on the 9 kHz European channels the K9AY was very
often better than the Beverage antennas. For example I heard HLAZ
Korea on the K9AY almost like the proverbial local station. Simply
by "switching off" County Sound, and then HLAZ was on top. Nothing
on any of the Beverage antennas! Simply because County Sound was
audible on any antenna. OK, with a phaser it would have been easy
to phase out County Sound, but without one you could forget Korea.
Next example: 1557 kHz, Family Radio from Taiwan. Again, I "switched
off" France, and in the remaining mess of croatian and UK stations
they came through. Nothing on a barefoot Beverage antenna. Wilhelm
tried it with his SEM phaser, reception then was on par with my
K9AY.
OK, in these cases there was no beverage pointing towards Asia available,
only the backbeams of some antennas. But even when the desired station
was in the beam of the Beverage it was not always possible to get
this station. An example was 1314, with the powerhouse from Norway
and Italy sharing frequency. Not a beep from Italy on the 180° Beverage,
with the K9AY I could switch back and forth between Italy and Norway.
If you're interested, I made a real audio file (91 kB) of this and
you can listen for yourself.
No problem at all when you use a phaser, but the pure Beverage didn't
make it.
Amazing, but reception during daytime was usually better on the
K9AY than on the Beverage-antennas. E.g. R. Bloemendaal, 1116 kHz,
came in best on the K9AY at 1340 UTC. Or the UK local "Fresh AM"
on 936 kHz was absolutely in the clear on the K9AY, while on every
Beverage there were traces of Radio Bremen.
Results on shortwave. I had expected that the K9AY would
show at least a little bit of directivity on 90 and 60m. But no,
it behaved like an omni-directional antenna. In every case better
than the longwire, but the Beverage-antennas had better signals.
On some frequencies one could separate stations easily with the
Beverages. E.g. 11955, where I had Angola in french and a Chinese
speaking station. Switching to the 180° antenna left nothing from
the Chinese, only Angola was audible. Another example was 11925
kHz, R. Bandeirantes and a Chinese.
The K9AY brought good and strong signals, very clean. But compared
to the appropriate Beverage it came only out as second winner. Only
on very high frequencies the K9AY had the edge, WJFP on 25870 kHz
was audible only the loop.
In general, the K9AY turned out to be an excellent performer,
able to beat the Beverages in some cases. But: Who of us has the
space to erect 16 Beverages? But many of us will have a piece of
garden of 8x8 meters! If you have a garden, you should really consider
this antenna. |
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