A User's Review
The Wellbrook K9AY Antenna
by John Bryant
The Wellbrook K9AY Antenna consists
of two chassis mounted in substantial plastic boxes:
the Operator's Unit and the Antenna Head Unit. The
user supplies the necessary wire loops, mast, lead-ins,
etc. to create the complete classic "Christmas
tree-shaped" K9AY antenna.
The Operator's Unit provides
a rotary Nulling Control and a five position rotary
switch for changing beam-direction of the antenna
through the four cardinal points and an omni-directional
setting which engages both loops. This latest model
of the Operators Unit also includes a toggle switch
for engaging/disengaging the low noise amp and a
small red LED indicating whether 12 vdc. power is
applied to the unit. The rotary switch (instead
of two toggles), the switching capabilities of the
amp and the LED are all welcome additions to what
was already a user-friendly product.
My current installation of the
Wellbrook K9AY employs an imported black telescoping
fiberglass mast produced by German radio amateur,
DK9SQ, which rises to 33 feet when fully extended.
I have installed guys at mid-mast height and my
loops, which are equilateral with 28 feet per side,
are attached at the 26 ft. height of the mast. The
Antenna Head Unit is mounted approximately three
feet off the ground. My grounding system is composed
of ten 18 in. long metal rods surrounding the base
of the mast in two concentric rings. The outer ring
is about three feet in diameter.
My grounding situation here in
Oklahoma is very good, with the rods going directly
into moist clay soil. I erected the loops parallel
to my two 500 ft. long Beverage antennas, which
run approximately 90 degrees to each other. This
was primarily done so that I might compare, as nearly
as possible, apples to apples and oranges to oranges
between the two antenna systems. I should note that
the beverage wires run no closer than 75 feet to
the K9AY and I maintain both ends of the beverages
in a grounded condition while using the K9AY. I
do not believe that there is any significant coupling
between the two antenna systems.
Wow!!! I am deeply in love with
the Wellbrook K9AY! After five months of use, I
am still continually amazed at the directional capabilities
of the antenna, especially on the broadcast band.
Despite my now rather extensive experience with
this antenna, I still find it hard to believe that
an antenna that can be fit in a 30 foot cube of
space can perform SUBSTANTIALLY better than 500
foot terminated Beverages on medium wave. It does.
While Wellbrook make no claims
of directional characteristics at much above the
broadcast band, I can usually detect mild directional
characteristics as far as the upper extent of the
60 Meter band - 5.100 MHz. The directional characteristics
on 90 meters - 3.3 MHz - are quite pronounced, being
clearly evident on signal after signal.
I am not really an expert at
DXing low frequency signals. I loaned the K9AY to
Bill Bowers, one of the leaders of the North American
"lowfer" hobby, for about two weeks so
that he might evaluate that aspect of it. He was
quite impressed and has reviewed it in a recent
Lowdown, the journal of the LWCA.
While the antenna was at Bill's,
we spent a couple of hours making front-to-back
ratio measurements on both MW and long wave. Since
my interests are primarily in MW and SW right now,
I left my notes on long wave for Bill's use.
However, we were achieving
nulls of about 20 dB quite easily. A CAUTION: We
were measuring these "nulls" on Non-Directional
Beacon channels; there was usually another beacon
in the "null" of the dominant beacon.
I would guess that the absolute nulls were running
more nearly 30 dB. In any case, though, the directional
characteristics on long wave were very significant
and enabled us to hear two separate NDBs on the
same channel quite well, when they separated by
either 90 or 180 degrees of azimuth. I would guess
that any "lowfer" who chases NDBs and
who has not yet experienced DXing with a true cardioid
pattern antenna will feel that he has an entire
new hobby as soon as he tries this K9AY.
My primary interest in the K9AY
antenna is for use in DXing international medium
wave signals from the North American NW Coast during
my visits there in the summertime. There, we use
1000 to 1500 ft. Beverages to DX MW signals from
across the Pacific. These long antennas limit our
choice of DXing sites rather severely, since we
must find property which is accessible for a specific
distance back from the beach and yet is an isolated
enough location that tourists and local people won't
stumble into the antennas.
This spring, both Guy Atkins
and I tested the Wellbrook K9AY while at our favorite
Washington State DXpedition site. We independently
concluded that the K9AY performs at virtually equal
levels on medium wave when compared to 1000 ft.
Beverages that we normally use there.
Except for the 10 day DXpedition
to coastal Washington, my MW DX testing of the K9AY
antenna has involved attempting to DX Mexican and
other Latin American signals from my home in central
Oklahoma. From this location, Latin America spreads
out over almost 180 degrees of the horizon with
the Leeward Islands in the Caribbean bearing about
100 degrees from me and upper Baja California bearing
west at 270 degrees.
Since I am almost 1000 kilometers
from the Mexican border, most of my local dominant
signals are from various outlets in the central
part of the United States. Unfortunately, many US
stations are almost perfectly "off the back
side" of my box loop antennas, making a Latin-directed
MW hobby very difficult from here. In a my area,
most channels on the lower half of the dial are
dominated by regional and national clear channel
Using the K9AY antenna, I can
receive clear reception from at least one Latin
signal on almost all of these frequencies during
the early morning and early evening DX time periods.
On many frequencies in the "low band"
I have multiple Latin signals previously masked
by 50 KW US stations. In essence, the cardioid pattern
of the K9AY has given me an entirely new lease on
MW hobby life here in Oklahoma. Now, if it could
just grow hair on my head....
I have not DXed domestic medium
wave stations since the early 1960s. However, I
suspect that people who do and who have a even a
small suburban lot to erect the "corner-of-the-yard"
version of the K9AY are going to throw away their
Viagra prescriptions and get back to a REAL hobby.
An electronically rotatable cardioid pattern that
works on MW and takes up very little real estate.....
While the antenna was at
Bill Bowers' shack, I made quite a few front-to-back
measurements on MW, using Bill's W-J HF-1000 with
an outboard meter accurately calibrated in dB. Even
at mid-day, it was difficult to find a signal which
was "alone" (having no weaker signal in
the null of the dominant). I did manage to find
three singleton stations in the low band and measured
nulls in the 25 to 30 dB range. However, my guess
is that there is still some residual energy from
secondary stations or even adjacent channel stations
that partially infilled the theoretical null. In
truth, no matter the accuracy of the instrumentation,
I don't think that its possible to realistically
measure the depth of a null on MW in central North
America outside of a giant Faraday cage. What counts
for me is that I hear LOTS of stations, EASILY,
that I could never hear before.
I mentioned previously that the
directional characteristics of the antenna are noticeable
all of the way to 5.100 MHz. I must say, tho', that
the terminated beverage antennas, which are aimed
directly at my favorite Tropical Band targets, prove
to be superior to the K9AY on most occasions. However,
since my Oklahoma beverages are over 500 feet long
and require significant portions of the cow pasture
in which I live, the fact that the Wellbrook K9AY
works almost as well as my beverage array is really
In fact, the K9AY is the first
antenna, other than the beverages, on which I can
successfully DX the very unusual signals from Indian
regional stations which may be heard here with great
difficulty for about 30 minutes at dawn and dusk
during the winter half of the year.
Except for the beverages, no
other antenna, active or passive, has done as well
as the K9AY at detecting these signals. In fact,
the K9AY often "hears" the Indian signals
as well as does the beverage array. The only difference
is the K9AY tends to hear more band noise on these
frequencies than does the very narrowly directional
On the international shortwave
bands above 5 MHz, the K9AY performs very well.
It tends to be a very quiet antenna and does, I
understand, offer some possibilities of nulling
local noise even on these frequencies.
What I have not done yet, nor
to my knowledge has anyone else, is cut a set of
loops to the proper length to operate well on 60
meters. It is my understanding that the largest
circumference loop that should be used for a particular
frequency is .25 of the wavelength. That would be
about 49 feet or about 16 feet per side. My loop
and most of the others currently in use are almost
double that circumference. I look forward to some
experimentation with smaller loops late this summer.
Even using the oversized loops as at present, I
likely would abandon my beverages entirely, even
for shortwave, were it not for my interest in the
DXing the very difficult weak long-range signals
from the Indian Subcontinent on the lower bands.
I certainly don't expect to use my beverages here
in Oklahoma for MW DXing in the future. I never
thought that I'd say that.
The Ultimate K9AY
My use of the Wellbrook K9AY
antenna here in Oklahoma rather closely models my
use in the Pacific Northwest. In both cases, the
DX signals of interest come from about 180 degrees
of the horizon, while interfering signals almost
all come from the back-side half-circle. Given that
the deepest null of a cardioid pattern is fairly
narrow, I began wondering if having four loops (eight
directions) with one antenna for each 45 degrees
of azimuth would be useful in real DXing situations.
Despite laying myself open to
further charges of obsessive/compulsive disorder,
I figured that the additional cost would be worth
it, if I could benefit from the additional directional
choices at least ten percent of the time. Andy Ikin
of Wellbrook was kind enough to provide me with
an Operators Unit that can control two separate
Antenna Head Units... one for each two loops. (All
four loops are mounted on the same mast, making
a nice Christmas tree.)
My only formal test of the 8-way
vs. the 4-way system consisted of two pre-dawn hours
DXing Mexican MW stations from here in central Oklahoma.
I checked 12 different frequencies, most below 1000
kHz. Of those 12, having a choice at 45 degrees
was a significant advantage on nine of the channels.
The three where it "was not an advantage"
were all stations which so dominated their frequencies
that they were totally dominant through 135 degrees
of azimuth or so.
On the 9 channels where the 45
degree choice made a difference, it was ALWAYS the
advantage of achieving a more complete null on the
dominant signal to be able to hear the desired signal
more clearly. It also seemed that this extra nulling
capability was the most useful when trying to ID
a station in the very worst pile-ups.
Assuming that the stations were
evenly distributed around the horizon, the above
leads me to believe that the extra two loops would
make a difference on about 40% of my DX targets.
In subsequent months, that 40% to 50% has proven
to be the case. GOOD ENOUGH FOR ME.
My findings make sense for people
who DX MW, with the dense pile-ups coming from all
angles of the compass. The cardioid pattern has
a fairly sharp null and a very wide, more than semi-circular
peak. I would guess that lowfers who DX NDBs would
also find the extra nulling control an advantage,
though I don't know by how much.
Both Bruce Portzer and I noticed
a distinct directional "peak" in sensitivity
while on our DXpedition. This was quite unexpected.
The published horizontal (or azimuthal) sensitivity
patterns of the K9AY antenna indicate a broad, even
front lobe of almost 270 degrees of azimuth mated
to a very sharp vee-shaped rearward null. That matches
what we were hearing, except on weak signals which
were otherwise in the clear.
Sometimes, these stations were
significantly stronger on just one wire. Since the
wires were only 45 degrees apart in azimuth, that
really shouldn't have been happening. This effect
was most noticeable on the 5 or so Russian long
wave stations that we logged. Whether this was a
unique effect of our superb ground plane or beach-front
location, or whether this peak has been missed by
DXers who are limited to only four directional choices,
we had no way to determine. As other DXers with
four-loop arrays gain experience, we should all
be alert to this phenomenon.
Concerning the 4-loop array coupled
with the DK9SQ antenna mast: the extra weight and
downward tension from the extra two loops has caused
my telescoping fibreglass mast to partly re-telescope
during two of our storms here in Oklahoma. I had
no such trouble when only two loops of 20 ga. wire
up. After having the same thing happen the first
night on the Washington coast, I secured each joint
of the telescope with a stainless steel hose clamp.
I should also note that the experience with K9AYs
at the Newfoundland DXpeditions, while good, do
not appear to have been quite so wonderful as mine.
My guess is that differing ground
conditions may be to blame. The ground plane in
Oklahoma was excellent: very moist clay. The ground
in Washington was even better: Sandy soil completely
saturated with brackish seawater. Ground conditions
at the site in Newfoundland are a mixture of dry
sandy soil and rock, as I remember.
I am unsure whether the K9AYs
in Newfoundland were amplified, as is the Wellbrook
version. The Wellbrook amplifier seems to not be
needed much when doing domestic/Mexican DX here
in Oklahoma, but it made a world of difference in
hearing weak trans-Pacific signals on the Washington
Also, Jean Burnell noted that
their 2500 foot beverage was always superior (on
MW) to any other antenna for the direction in which
it was pointed. I'm sure that is true. I don't ever
expect to entirely give up my addiction to beverage
antennas. When I have the opportunity to string
out at least 1500 or more feet of wire toward an
area of interest, I'm certainly going to do so...
unfortunately, those opportunities are very rare,
even here in the world's largest cow pasture.
The K9AY antenna as produced
by Wellbrook Communications is a marvelous antenna
for medium and long wave DXing. Even though I have
not used a K9AY antenna cut for shortwave frequencies,
my medium wave version is second only to my 500
foot beverage antennas when DXing the Tropical Bands.
The Wellbrook units are very well built and appear
to be optimized for the needs of serious DXers.
I recommend the Wellbrook K9AY enthusiastically
and without reservation.
The only current source for the Wellbrook version
of the K9AY Antenna is from the manufacturer:
Communications, Wellbrook House, Brookside Road,
Bransgore, Christchurch, Dorset BH23 8NA, United
Kingdom, Tel. 01425 674174 Int.+44 1425 674174.
The proprietor of Wellbrook is Andy Ikin and he
is one of the "good guys". Andy Ikin e-mail
In North America the DK9SQ
telescoping mast may be obtained here.
Written in May 2000,
published on DXing.info on June 24th 2002