By Dave Kenny, British DX
Communication, September 1999
Back in November 1998, Andy Ikin of Wellbrook Communications
very kindly loaned me a pre-production model of a K9AY antenna
system by Wellbrook Communications.
It is based on a system designed by Gary Breed (K9AY) published
in the American ham radio magazine QST which Andy had tested
himself last summer (see K9AY Terminated Loop Antenna by
Andy Ikin, September 1998 edition of Communication).
system comprises a very neat control unit which plugs into
a 12v power supply (provided). From the control unit, a short
lead plugs into the aerial socket on the receiver and two feeder
wires (one is a standard RG58 coax, the other a 12v power supply
feed about the thickness of bell wire) connect up to the loops
which I constructed some 30m distant at the end of the back garden.
On the front of the control panel are two switches: the first
is used to select either A or B loop, the second to reverse the
beam of whichever loops is selected. To the right of the switches
is a small rotary control which is used to adjust the null.
itself consists of two large wire loops mounted at right angles
and a small connection box. You also need to connect an earth
to the connection box - I used a short copper pipe hammered into
the ground nearby, and thanks to all the rain we've had this summer,
the ground remained damp so there was no need to water it at any
stage; in a dry summer it's always worth giving your earth rod
a good soaking every week to help maintain good conductivity between
the rod and the ground.
for the loops was supplied in a 100m roll with instructions on
their construction. At first I found the design quite daunting,
but it is really quite straightforward and the actual shape of
the loops themselves does not seem to be particularly critical.
I supported the loops between the branches of three trees, the
garden fence and a shed roof and was pleased to find that once
up it was virtually invisible to the naked eye from the house.
If you don't have convenient trees you could also use a pole (preferably
non-metallic) or even perhaps wind the loops over a shed or outbuilding
- as long as they are away from sources of electrical interference.
The main thing is that each of the loops should be of a similar
size and at right angles to each other.
of the K9AY is that the control unit remotely varies the phase
of the two loops by varying the termination resistance, this effectively
enables you to steer a null electronically through 360 degrees
- without the need for any moving parts. On an ordinary MW loop
the signal peaks and nulls in two directions at the same time,
so if you are trying to receive a weak station 180 degrees away
from a stronger station, it is very difficult if not impossible
to null out the stronger station without also nulling out the
weaker station at the same time. With the K9AY however, the single
null enables you to switch very effectively between signals from
I was delighted to find that despite my very rough initial
construction of the two loops they worked straight away and despite
the summer daytime conditions prevailing, found that I could now
select either Atlantic 252 or Radio Algiers, both on 252 kHz -
virtually interference free - at the flick of a switch.
828 kHz I could now choose between Classic Gold from Luton or
Arrow Classic Rock from Holland virtually interference free -
this was also impossible with my other aerials.
On 1548 kHz, Capital Radio from London or BBC Radio Bristol -
1485 kHz, which is dominated by Classic Gold from Newbury in this
area, I could now hear BBC Southern Counties Radio from Brighton
by nulling out Classic Gold. This was previously impossible, as
with a conventional loop both Brighton and Newbury are approximately
180 degrees apart, so the nulls of both are in the same direction.
that night, for the first time, I was able to log two of the
1 Watt low power AM stations currently operating on 1350 kHz -
Radio Yare (Gt. Yarmouth) and Sunshine Radio (Liverpool) - for
the first time, and what's more, choose between them at the flick
of a switch! Signal strength and overall clarity was superior
on the K9AY to either my 100m Beverage or 30m long wire and this
was despite having constructed much smaller loops than recommended
in the instructions that came with the K9AY.
also surprised me to find that reception on shortwave frequencies
up to about 12 MHz was almost as good on the K9AY as on my 30m
longwire - although the directional properties of the phasing
system tail off above about 2 MHz so that on shortwave it acts
as an omnidirectional amplified wire, and although signal strengths
are somewhat lower than on the longwire, being further from the
house it is less prone to TV and other interference.
some four months of using the K9AY I find that I am completely
hooked and don't know what I'd do without it. On mediumwave, in
virtually all circumstances, it outperforms my 100m Beverage and
30m long wire providing stronger, clearer signals. One recent
annual RSL – Raven Sound, had proved elusive for several years
due to its exceptionally low signal strength, but with the K9AY
I was able to pull it out of the noise for the first time (no
signal at all on the other aerials).
afield, another first time for me was reception of the local Radio
Rurale station in Labe, Guinea on 1386 kHz, heard clearly on the
K9AY, but again inaudible on the other aerials. With the three
recent "offshore" RSLs it has made the difference between
good almost 100% listenable reception, to poor, often noisy signals
on my other antennas.
While I was writing this review on 22nd August it again
proved itself by enabling me to receive Radio Silverstone on 1602
kHz clearly for the first time by nulling out BBC Radio Kent on
the same frequency.
for anyone interested in mediumwave DX I can heartily recommend
The version I tested came with a 15dB amplifier which more than
proved its worth, especially with the smaller loops I built. Ideally,
the two loops should be 25m in circumference, but the ones I constructed
were only about half that size - for which you will need around
5m x 5m of garden space to erect them.
Although the instructions advise that the lower part of the loops
should be a minimum of 0.5m off the ground, mine just lies on
the lawn and it seems to work well enough - it achieves nulls
of between 30-40dB on most MW signals. I can only wonder at the
sort of results that would be achieved with a full sized loop
raised off the ground, but I would need to move house first as
my garden is typical of most Victorian terraces, being long but
narrow - only 5m wide.
the K9AY and other aerials are available from Andy Ikin at Wellbrook
Communications, Wellbrook House, Brookside Road, Bransgore, Christchurch
BH23 8NA. Tel 01425 674174.
Reproduced with author's permission. First published
in Communication, September 1999. Communication is the monthly
journal of the British