[OZAPRS] rf earth

[Paul Mullins]

That should work ONLY if the steel sections are in cased in ground, its all
about surface contact area, skin effect is the word.
This is the reason why I buried bare copper wire in the ground between
stakes.
Also burring wire in a garden is great moist ground is going to work heaps
better than dry , I know bashing the bible again.




To test the earthing system what we did in 'ETSA' the local power supplier.

You need about 10 meters of hookup wire, a low ohms meter ie has to read 2
ohms or better, with the hookup wire connected as a loop to the meter zero
the meter.
Connect one end of the hookup wire to your earthing system, "make sure there
is NOT MAINS VOLTAGE PRESENT" believe it or not some stobbie poles are alive
remember safety first people. I DON'T WANT TO HEAR OF PEOPLE GETTING HURT, I
mean this.

So one end is connected to the 'earth system' to be tested, now run the long
wire out in a direction that there is NO EARTHING SYSTEM, drive a long steel
stake into the ground, we used a stainless steel stake or screw driver,
needs to go about 1 foot (30 cm) then measure the earth resistance, good
earthing should be below 1 ohm, if you feel up to it and you check your
mains earth system , extreme caution, as a sparky I have found broken earth
bonds and all sorts of potential life shorting bad connections.

My house when I bought it was getting boots from the hot water system in the
shower, now my hot water is gas right. Should not get any thing, I measured
with an ANALOGUE meter digital ones don't work for this part that I had 12
volts AC. This is enough to make a lot of hertz, a sparky joke.

I found my house main earth to be substandard, fixed it with a new copper
stake just below the meter box, the original one was connected to the mains
water, I re did the complete earthing system, new stake, bonds from the
earth bar to the cold water and the hot water, a long time ago the gas
supply pipe to people was steel and this use to get bonded, mines steel and
it now got a wire, people with plastic incoming gas mains could bond the
steel part IE the consumers side as that is normally steel / copper.

NOW ANOTHER WORD OF WARNING.

Only licensed people should play around with 240 volts mains, this is what
the law states, if you are competed I think that's the right word, you could
make a great earthing system, ALSO you need to keep the two system apart
easy said. Also beware of potential voltage differences on the two earthing
systems, As I said my RF earth is better than my mains earth, so be aware .

Old motto from school days.


TEST BEFORE TOUCH.

If you keep a level head and plan out you will live.  

Any way I got my booting from 12 volts AC down to 50mV I can live with that




I am sorry about the long winded way of explaining, but I have to make sure
people are going to do it safely.
Remember that RF is a power source so make sure no radios are TXing, RF
burns are worse than power burns trust me, they take months to heal up,
nasty stuff.


STAY ALIVE

Paul




-----Original Message-----
From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
Behalf Of Rodney Mitchell
Sent: Tuesday, 27 April 2010 1:17 AM
To: Australian APRS Users
Subject: Re: [OZAPRS] rf earth


> Hi All,
>
> I intend on using shed as an RF earth since it is all bonded together
> and is in the ground with steel "C" section.
>
> Is this a good idea or is it better to use earth rods.
>
> thoughts or suggestions would be much appreciated
>
> cheers
> Ben
> VK5JFK
>


Hi Ben,

What are you doing? Antenna earthing to simulate a the other half of a
vertical 1/4 wave?

Regs, Rod.

-- 
VK5KFB
--------------------------------------------------
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