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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Make
yourself a portable K9AY
By Al Merriman - K4GLU
The base is 30 inches square and is made out of 2x4.
A piece of 2x4 is used across the middle in one direction as a brace
and across the top at a 90 degree angle I use a piece of 1x6.
In the middle a 2" galvinized pipe flange is installed.
A piece of 2" pipe, 2' long is used as a bottom support for the
mast.
To help hold the frame down 2 screw eyes are installed on each side
of the inside of the base frame - total of 8.
Tent stakes are used as holdowns. The ones I use came from Walmart
- I don't remember the brand. They are about 15" long, v shaped
and at the top there is a L shaped hook. These are driven in right
next to the screw eye so that the L hook goes inside the eye.
The same tent stakes are used to support the corners of each loop.
To secure the ends of the loops at the base of the mast I
used 4 pieces of 1x3 about 10" long and put them together so that
they formed a square block that slides down over the 2" base support
pipe.
On each side of the top of this block I use a screw eye to support
each end insulator.
On each side at the bottom of the block there is another screw eye
- all of which are tied together with a piece of wire. This is used
as the common point for connecting the 4 conterpoise wires.
Before I forget, the base is put together using 1/4 x 3" lag screws.
A note. All base dimensions were simply pulled out of a
hat - there is nothing scientific about them. From observations
so far the base could probably be made smaller and lighter and still
work well.
The mast I use is called a "Portaple". This is a seven section
collapsable mast made from aircraft aluminum and extends from just
under 6 feet to about 26.
The only source for this that I know of is Amateur Electronic Supply
and at $150.00 plus shipping it is the most expensive part of the
setup - but in my opinion its ease of use more than makes up for
the expense.
When using a metal support you have to be sure it is not grounded
or the loop patterns will be affected.
A mast using wood, pvc pipe, etc could probably be devised but I'll
leave that to others.
The antenna. Just about any type of wire can be used but
I would advise something fairly heavy as the antenna doubles as
the mast guys.
I used some number 14 teflon insulated wire that I happened to have
on hand.
As a top common insulator for both loops I use a 15" or so piece
of 1 1/4" pvc pipe.
Near the top two holes about 1" apart and at right angles to each
other were drilled and are used to secure the middle of the loops
in place. This pvc pipe fits nicely over the top of the metal mast.
About 6 inches from the bottom I put in several sheet metal screws
to keep the pvc pipe from sliding too far down the mast.
A pvc end cap is used on the top.
The corner loop insulators are slipped over the wires and left to
float - don't lock these in place - they automatically adjust when
the corners of the loops are tied off.
At the end of each loop segment I use a plastic insulator - the
wire is attached to one end and in the other I drilled a hole into
the body of the insulator and installed a metal hook which is used
with the screw eye in the bottom support at the mast to make a "quick
disconnect" tiepoint for the loop ends.
Total length of each of my loops is just over 90 feet - 30 feet
on each side plus whatever extra is needed at the base to make the
connections to the relay/termination box.
The counterpoise. 4 pieces of number 14 bare wire are used.
At one end of each wire I installed a heavy clip which is used to
attach each wire to the common point at the mast base.
One of these wires is then run directly under each of the loop segments
and is wrapped several times around the tent stake that is used
to secure the loop corners.
That's it.
This setup takes 30-45 minutes to have up and running so
it makes for an excellent portable antenna.
It is also DXpedition proven - mine was taken to Newfoundland this
year and was a huge hit. |
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