[TowerTalk] Fwd: buried radials problem

Wed Mar 6 00:07:35 EST 2013

You have a conductivity problem due to a lack of moisture in the soil. 

Here in New England I have made measurements of conductivity. The value
varies all over the place. And I never found the "textbook" value.

The climate here has little dry spells. Winter is the driest time as the
ground is frozen from mid December to about now. Your climate may have
annual wet and dry times. This can be a problem.

I also think you may have a wire corrosion problem. I suggest you use
Copperweld wire. This is steel wire covered with copper. Never, never use
"Aluminum-weld" wire as it will corrode within a few years in the ground.

Let me suggest a better way:

Set up a vertical with raised radials. You only need three radials, but
they should be cut to a quarter wavelength long. I have the radials about 8
feet (2 1/2 meters) above the ground. 

This height isn't a magic number, it is just high enough so that deer and
an occasional moose (a large elk-like animal) can pass under the radials. 

The vertical section starts at the height of the radials. It can be a
quarter wavelength or about 5/8 wavelengths high. 

My antenna has about 33 foot radials, is about 31 ft long, starting from 8
feet, going to about 39 feet high. I use a expanding fiberglass tube,
bought from Hamsource, to hold a radiator of flex-weave wire. I use some
hot-melt glue to hold the wire at the top of the pole. 

This antenna works fairly well on 40 and 15.

Now compare this raised radial antenna against your present antenna. I
think you will be pleased. 

Jim, W1EQO

Original Message:
-----------------
From: Steve Rodowicz vze2prfs at verizon.net
Date: Tue, 05 Mar 2013 18:08:03 -0500
To: w1eqo at shaysnet.com
Subject: Fwd: [TowerTalk] buried radials problem

-------- Original Message --------
Subject: 	[TowerTalk] buried radials problem
Date: 	Tue, 05 Mar 2013 08:36:22 -0800 (PST)
From: 	Eduardo Araujo <er_araujo at yahoo.com>
To: 	towertalk at contesting.com

Dear people, I experience a situation that confused me a little bit.

I have a vertical with 60 iron fence wire buried radials 1/4 wave long plus
a ground rod. I installed it 2 years ago lying on the ground and now they
are buried.

Prior to the contest I decided to check the buried radials of my vertical.
I have bundles ranging from 4 to 7 radials connected to a square ring
around the base of the tower. I provided 20W input and I measured the
current entering each of the bundles which is a procedure I have done many
times.

To my big surprise there was little to no current entering most of the
bundles except one which also had a ground rod besides the radials.

This bundle took aprox 80% of the total current. Then I decided to measure
the current entering the ground road and it was aprox 100% of the total for
that bundle.

This situation was the opposite I always had measured before where the
ground rod practically had insignificant current.

2 months had passed without any rain so I tried to spread some water around
a radius of 4 meters but situation didn´t change dramatically but yes an
small increase in all radials current

That night I thought a lot of possibilities but the strongest one was that
for some reason most of the radials had dissapeared or at least have been
reduced to short ones.

Next day we have 27mm of rain. Another surprise, everything back to normal.
I had current in all bundles and almost nothing into the ground rod.

I expected that having 60 radials it should not matter if it rains or not.
I expected to have a relative good shield of the ground

Question 1: Any guess what could be going on ?

Question 2: Is it a normal situation? Does anyone experience the same?

Question 3: Could it be possible that radials could have been eaten by the
soil and I am having very short ones? and that made them so much soil
conductivity dependent?

Question 4: if the soil is so dry why the ground rod collect so much
current from the same soil?

As I have no explanation so far, I am planning to add another 60 radials
and for a reason of cooper cost I am planning to use what I think should be
similar to what I read here many times as WD1. It is for exterior telephony
drop consisting of a pair of 0.8 mm of stiff wire which looks like iron
covered by cooper and both separated by 3mm of a very heavy plastic. I
measured 13 ohms of DC resistance in 60 mts of wire.

My plan is to split the 2 wires and use them as radials.

Question 5: It is a good or a bad idea to use this kind of wire instead of
fence wire?. Cooper will be the last option of course

Many thanks in advance for your opinions.... Eddy, LU2DKT

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