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Old September 7th 18, 09:53 AM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default Earth rods, etc

On Fri, 7 Sep 2018 09:21:15 +0100
"Jim GM4DHJ ..." wrote:

On 9/7/2018 9:06 AM, Stephen Thomas Troll wrote:
On Thu, 6 Sep 2018 18:14:51 +0100
Gareth's Downstairs Computer
wrote:

On 06/09/2018 17:22, Jeff Liebermann wrote:
On Thu, 6 Sep 2018 14:46:33 +0100, Gareth's Downstairs Computer
wrote:

Interesting because between the house TT earth, a steel rod and
the copper RF earth is now about 0.4 volts, making the ohmmeter
go haywire trying to measure the resistance between them.

That's only true if there's an electrolyte between the copper and
steel. When bonded together, there's no galvanic action or
voltage. If you're using two or more ground rods, all electrical
codes specify that they need to be connected together with some
heavy gauge wire.

Separate RF earths to reduce noise on RX and protect family members
from RF hazard if touching central heating radiator 1/4 wavelength
away.


Gareth, get some double glazing, Gareth, that would stop them
huddling around the radiators, Gareth.


Gareth, Thanks, Gareth.



I had a radiator that rusted through....just thought you would like
to know that ....



Jimbore, too tight to buy inhibitor, Jimbore?



Jimbore, Thanks, Jimbore.


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Old September 7th 18, 12:56 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default Earth rods, etc


"Stephen Thomas Troll" wrote in message
...
On Fri, 7 Sep 2018 09:21:15 +0100
"Jim GM4DHJ ..." wrote:

On 9/7/2018 9:06 AM, Stephen Thomas Troll wrote:
On Thu, 6 Sep 2018 18:14:51 +0100
Gareth's Downstairs Computer
wrote:

On 06/09/2018 17:22, Jeff Liebermann wrote:
On Thu, 6 Sep 2018 14:46:33 +0100, Gareth's Downstairs Computer
wrote:

Interesting because between the house TT earth, a steel rod and
the copper RF earth is now about 0.4 volts, making the ohmmeter
go haywire trying to measure the resistance between them.

That's only true if there's an electrolyte between the copper and
steel. When bonded together, there's no galvanic action or
voltage. If you're using two or more ground rods, all electrical
codes specify that they need to be connected together with some
heavy gauge wire.

Separate RF earths to reduce noise on RX and protect family members
from RF hazard if touching central heating radiator 1/4 wavelength
away.


Gareth, get some double glazing, Gareth, that would stop them
huddling around the radiators, Gareth.


Gareth, Thanks, Gareth.



I had a radiator that rusted through....just thought you would like
to know that ....



Jimbore, too tight to buy inhibitor, Jimbore?



Jimbore, Thanks, Jimbore.

it was at the van and the previous owner didn't even have anti freeze in it
never mind inhibitor....no big deal the rad was 20 at screwfix.....


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Old September 7th 18, 03:37 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default Earth rods, etc

On 9/6/2018 5:46 AM, Gareth's Downstairs Computer wrote:
Unearthed the previous fan of plumbers' copper microbore tubes
and associated ground rod to find a corroded and non conductive
mess and raised the question of how to protect underground
junctions from the worst that nature could throw at them?

Firstly, resurrecting a technique from school metalwork lessons
from 53 years ago when brazing things together, dig out the
gas torch, soldering flux***** and solder and connect all together
electrically.

Secondly, to protect the now-relatively-massive joint, smear with
petroleum grease. Was this a good idea, and is there something better?

***** Curious as to whether could be combined with one's radio
interest to nake a flux capacitor to go time travellingg :-)



I don't know how to protect it, I recently installed ground rods and
figure to periodically test them and replace as needed.
I ran a 253ft BOG antenna, I needed a ground at each end.
I started with 1-five ft 1/2" copper pipe, with predrilled 1/8" hole
running down and around the pipe. I used the method on page 25 of this
pdf to measure the ground resistance.
http://www.weschler.com/_upload/site...owntoearth.pdf

I had a pair of wires ran from my home to each end of my BOG antenna
so it was convenient to connect it to a variac driven by an isolation
transformer. I used that as my voltage source*. I set it at about 40V,
but measured the voltage at the ground rods for calculations, because
of the voltage drop of the feed wire.
My first measurement was 112 ohms, both ends 253 apart were basically
the same even though I had 3 rods at one end and 1 rod at the other. I
added 2.5lbs of Calcium Chloride at one end by pouring the water/Calcium
Chloride solution into the three copper pipe ground rods. After a few
hours a retest showed a drop from 112ohms to 73 ohms. The next day it
was down to 60 ohms. About a week later I added another 3.5lbs of the
Calcium Chloride solution into the copper pipes, this brought the
resistance down to 34 ohms.
I added 2 more rods to the other end and added more Calcium Chloride,
that brought the end down to 24 ohms.
The measurement at one end 22.35V and 660ma for 33.9 ohms.
The other end 13.14v and 580ma for 23.9 ohms. Lower voltage because my
240ft feed line was a much smaller gauge and had more voltage drop.

* I know 60hz drive voltage is not ideal but, I didn't have a signal
generator with enough power do the job.
http://www.esgroundingsolutions.com/...stance-meters/

There are some papers saying DC better to measure earth ground, I
don't know.
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Old September 9th 18, 10:32 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default Earth rods, etc

On 9/6/2018 8:46 AM, Gareth's Downstairs Computer wrote:
On 06/09/2018 13:59, Rambo wrote:
On Thu, 6 Sep 2018 11:46:55 +0100, Gareth's Downstairs Computer
wrote:

Unearthed the previous fan of plumbers' copper microbore tubes
and associated ground rod to find a corroded and non conductive
mess and raised the question of how to protect underground
junctions from the worst that nature could throw at them?

Firstly, resurrecting a technique from school metalwork lessons
from 53 years ago when brazing things together, dig out the
gas torch, soldering flux***** and solder and connect all together
electrically.

Secondly, to protect the now-relatively-massive joint, smear with
petroleum grease. Was this a good idea, and is there something better?

***** Curious as to whether could be combined with one's radio
interest to nake a flux capacitor to go time travellingg :-)


cathodic protection?


Interesting because between the house TT earth, a steel rod and the
copper RF earth is now about 0.4 volts, making the ohmmeter go haywire
trying to measure the resistance between them.

Yet another ground to contend with is whatever may come with a cable TV
connection. (Sorry for my ignorance, I am not sure how to translate for
the other side of the Atlantic! In the US we typically have a 75 ohm
coax coming in for this purpose.) At another residence I had about 3
volts between that ground and the ground for AC power. When I connected
the coax to an FM tuner in the music system, to play an FM station that
was carried at baseband, that put 3 volts between the tuner's antenna
connection and its power connection (until I eventually put in some
isolation...) There was a lot of hum out of the system with a 300 watt
audio amp feeding the speakers!
Bob Wilson, WA9D
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Old September 9th 18, 10:51 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Mar 2017
Posts: 209
Default Earth rods, etc

On 09/09/2018 22:32, Bob Wilson wrote:
... There was a lot of hum out of the system with a 300 watt
audio amp feeding the speakers!



Somewhat reminiscent of the opening sequence in
one of the Back To The Future films!

Or, going back some years to the April Edition
of Wireless World and the article by the
Dutchly-named George Izzard O'Veering.




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Old September 9th 18, 10:55 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default Earth rods, etc

On 09/09/2018 22:43, Ralph Mowery wrote:
In article , says...

Yet another ground to contend with is whatever may come with a cable TV
connection. (Sorry for my ignorance, I am not sure how to translate for
the other side of the Atlantic! In the US we typically have a 75 ohm
coax coming in for this purpose.) At another residence I had about 3
volts between that ground and the ground for AC power. When I connected
the coax to an FM tuner in the music system, to play an FM station that
was carried at baseband, that put 3 volts between the tuner's antenna
connection and its power connection (until I eventually put in some
isolation...) There was a lot of hum out of the system with a 300 watt
audio amp feeding the speakers!
Bob Wilson, WA9D



All ground rods and other earth grounds have to be bonded together or
you have no real ground system.

That is you can not have a ground rod on one side of the house connected
to something and another ground rod on the other side of the house
connected to other equipment unless you run a bonding wire between the
two.



I offer the example of an outhouse in a PME supplied household where the
PME earth must not be exported to the outhouse where a separate TT
earth rod, not bonded to that of the house must be supplied.

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Old September 10th 18, 09:42 AM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default Earth rods, etc

Bob Wilson wrote:
Yet another ground to contend with is whatever may come with a cable TV
connection. (Sorry for my ignorance, I am not sure how to translate for
the other side of the Atlantic! In the US we typically have a 75 ohm
coax coming in for this purpose.) At another residence I had about 3
volts between that ground and the ground for AC power.


A modern cable TV demarcation point has galvanic isolation.
With a TV there usually is no problem because it usually has galvanic
isolation in its input circuit as well (some ferrite bead transformer
between the input and the tuner).

For radio tuners that may be different.
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Old September 10th 18, 09:19 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default Earth rods, etc

On Fri, 7 Sep 2018 09:37:53 -0500
amdx wrote:


I ran a 253ft BOG antenna,


What DX did you hear with it and on what band(s)?


--
Mouse.
Where Morse meets House.

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Old September 12th 18, 03:23 AM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default Earth rods, etc

On 9/10/2018 3:19 PM, A. non Eyemouse wrote:
On Fri, 7 Sep 2018 09:37:53 -0500
amdx wrote:


I ran a 253ft BOG antenna,


What DX did you hear with it and on what band(s)?



I ran it for the AMBCB. It was clearly directional.
I'm in the Panhandle of Florida and I pointed it North.
It is a quiet antenna and the best of the 3 antennas I have.
I suspect It will work well on 160 and 80 meters, but My R-71A
has a SSB problem and until I fix that, I can't check.
Mikek


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