[HCDX] K9AY loop installed

["plimmer" <plimmer@xxxxxxxxxxx>]

    After much work, the K9AY is now installed and has been tested over
three nights against the reference of the British Datong AD370 active
antenna.

The two loops are approximately 16 meters/50 foot in length and have been
installed as per the instruction sheet. Care has been taken to obtain
maximum separation of the wires entering the HEAD unit. the top of the loops
have a 30 cm/1 foot separation. The bottom of the loops are 50 cm/1 1/2 feet
above ground.

The earth consists of 4 meters/13 foot of 5 mm heavy gauge copper earth wire
buried 75 mm/3 inches below the surface of the ground in 4 X 1 meter/3 foot
lengths
(no earth rod is possible due to the solid rock just below the surface). The
ground has been watered to try for a better ground connection.

I have tested the K9AY with the amplifier on against my reference ageing
Datong AD370 active (amp off).
Results on MW are poor and disappointing. Signal strength is poor and there
is much electrical QRM
The Datong by comparison is much quieter and produces a much stronger
signal.
The Datong receives much distant MW DX clearly that is unreadable when
switched to the K9AY.

All settings on the control unit have been experimented with and optimised.
That is the North, South, East, West loop settings together with the phasing
control.
Use of the different loops and the phasing control do not eliminate the
electrical QRM much.

Results on the higher SW bands on the K9AY are the same as the Datong, but
with a tendency to pick up more electrical QRM.
Tropical band reception is as for SW, that is good but noisy.

I have checked the fault finding instructions carefully and tested all
voltages which are as per specification.

This is a disappointing result after a lot of effort and cost.

This is a half size K9AY, as the full system calls for a 7 m/25 ft high peak
for two X 25 m/80 ft loops. It had been hoped though, that these smaller 16
m/50 ft loops (up 4.5 m/15 ft) would still give a strong performance, but
not so!
Also is the fact that the street overhead powerline is ten meters/30 foot
from the top of the K9AY, generating a lot of noise on the antenna, but this
is not being picked up by the Datong. Yet the K9AY is supposed to resist
random electrical noise better, but this is not the case here.

Another observation that I have, is that the "phasing" and nulling of far
distant signals is not nearly as successful as the pundits would have you
believe. I also have a modified for MW MFJ 1025 and a Kiwa MW loop, neither
of which are very good at nulling the local stations that are 150 and 1200
kilometers away. Dont get me wrong, they do null signals to a certain
extent, but never enough to receive a further off weaker MW station.

This in itself is a long discussion, but fundamentally you are not going to
null out a 100 Kw S African station to obtain a European station 10,000 Km's
further North on the same axis. I think the problem is that these are all
high angle "skywave" signals that do not lend themselves to nulling.

Dont get me wrong, this construction has not worked for me, but I went to
all this trouble to erect it because there are many users who have great
success with the K9AY antenna system.

Two reasons I offer for my failure are that the solid rock, just 75 mm/3
inches just below the surface, may prevent a good earth ground system,
required for this installation. Plus the nearby close proximity of a noisy
overhead powerline.

I would not like others to be put off from experimenting with this system.
Many references to it can be found on the web by searching "K9AY"

The head and control units were supplied by the British company Wellbrook at
a price of GBpounds 140, see www.wellbrook.uk.com who have kindly offered to
"refund the purchase price" if I return it.

Anyone have any views as to why this experiment didnt work.
Please post me direct as I am not subscribed plimmer@xxxxxxxxxxx

John Plimmer, MONTAGU. Western Cape Province, Republic of SOUTH AFRICA


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