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Antenna Isolator install


Will Grocott
 

Does anyone have any installation advice for this device? I saw this on the web page and it sounds like it is something I should have.

I see 3 screw terminals and a SO239: what are the 3 screw terminals and how would I typically connect this? I have a ground mounted vertical and a 10m Zepp antenna in a house with a PME grounding scheme

Many thanks
Will

2E0WCJ


Chris Moulding
 

The antenna isolator shown on the web page is one I've designed for use with isolated loop counterpoises.

I recently wrote an article on loop counterpoises showing how isolating them almost eliminates local electrical noise in vertical antennas. It was one of my projects when stuck at home during the lockdown. 

The article has been published in this month's edition of the Radio Society of Great Britain magazine RadCom.

The three terminals are looking at the label with the coax connector down...left hand side antenna, right hand side insulated loop counterpoises or ground if insulated loop counterpoises are not used and the top connector is a connection to the ground side of the transformer via a 1 M ohm resistor and a 20 kA gas discharge tube to safely protect the isolated loop counterpoises from static electricity and nearby lightning strikes.

If you can read the article in RadCom it explains it more than I can in a forum post.

Regards,

Chris G4HYG

On 18 Sep 2020, at 18:46, Simon <ohhellnotagain@...> wrote:

Hi Will

That didnt make alot of sense..( to me anyway.)

Please explain what you want to do?
What antenna etc

Much much more info pls.

Mag loop Simon G0zen 

On 18 Sep 2020, at 18:10, Will Grocott <wjcgrocott@...> wrote:



Does anyone have any installation advice for this device? I saw this on the web page and it sounds like it is something I should have.

I see 3 screw terminals and a SO239: what are the 3 screw terminals and how would I typically connect this? I have a ground mounted vertical and a 10m Zepp antenna in a house with a PME grounding scheme

Many thanks
Will

2E0WCJ


Will Grocott
 

Thanks for the reply Chris. I’ll be sure to take a read when it arrives. 

Thank you
Will
2E0WCJ


Simon
 

Hi Chris

Dont suppose you could send a copy of your paper to me via email??

Interesting..Simon g0zen

On 18 Sep 2020, at 19:00, Chris Moulding <chrism@...> wrote:

The antenna isolator shown on the web page is one I've designed for use with isolated loop counterpoises.

I recently wrote an article on loop counterpoises showing how isolating them almost eliminates local electrical noise in vertical antennas. It was one of my projects when stuck at home during the lockdown. 

The article has been published in this month's edition of the Radio Society of Great Britain magazine RadCom.

The three terminals are looking at the label with the coax connector down...left hand side antenna, right hand side insulated loop counterpoises or ground if insulated loop counterpoises are not used and the top connector is a connection to the ground side of the transformer via a 1 M ohm resistor and a 20 kA gas discharge tube to safely protect the isolated loop counterpoises from static electricity and nearby lightning strikes.

If you can read the article in RadCom it explains it more than I can in a forum post.

Regards,

Chris G4HYG

On 18 Sep 2020, at 18:46, Simon <ohhellnotagain@...> wrote:

Hi Will

That didnt make alot of sense..( to me anyway.)

Please explain what you want to do?
What antenna etc

Much much more info pls.

Mag loop Simon G0zen 

On 18 Sep 2020, at 18:10, Will Grocott <wjcgrocott@...> wrote:



Does anyone have any installation advice for this device? I saw this on the web page and it sounds like it is something I should have.

I see 3 screw terminals and a SO239: what are the 3 screw terminals and how would I typically connect this? I have a ground mounted vertical and a 10m Zepp antenna in a house with a PME grounding scheme

Many thanks
Will

2E0WCJ


Tom Crosbie G6PZZ
 

And me!

Tom G6PZZ

 

From: CrossCountryWireless@groups.io <CrossCountryWireless@groups.io> On Behalf Of Simon
Sent: 18 September 2020 19:22
To: CrossCountryWireless@groups.io
Subject: Re: [CrossCountryWireless] Antenna Isolator install

 

Hi Chris

 

Dont suppose you could send a copy of your paper to me via email??

 

Interesting..Simon g0zen



On 18 Sep 2020, at 19:00, Chris Moulding <chrism@...> wrote:

The antenna isolator shown on the web page is one I've designed for use with isolated loop counterpoises.

 

I recently wrote an article on loop counterpoises showing how isolating them almost eliminates local electrical noise in vertical antennas. It was one of my projects when stuck at home during the lockdown. 

 

The article has been published in this month's edition of the Radio Society of Great Britain magazine RadCom.

 

The three terminals are looking at the label with the coax connector down...left hand side antenna, right hand side insulated loop counterpoises or ground if insulated loop counterpoises are not used and the top connector is a connection to the ground side of the transformer via a 1 M ohm resistor and a 20 kA gas discharge tube to safely protect the isolated loop counterpoises from static electricity and nearby lightning strikes.

 

If you can read the article in RadCom it explains it more than I can in a forum post.

 

Regards,

 

Chris G4HYG


On 18 Sep 2020, at 18:46, Simon <ohhellnotagain@...> wrote:

Hi Will

 

That didnt make alot of sense..( to me anyway.)

 

Please explain what you want to do?

What antenna etc

 

Much much more info pls.

 

Mag loop Simon G0zen 



On 18 Sep 2020, at 18:10, Will Grocott <wjcgrocott@...> wrote:



Does anyone have any installation advice for this device? I saw this on the web page and it sounds like it is something I should have.

I see 3 screw terminals and a SO239: what are the 3 screw terminals and how would I typically connect this? I have a ground mounted vertical and a 10m Zepp antenna in a house with a PME grounding scheme

Many thanks
Will

2E0WCJ


Will Grocott
 

I’ve just read the article Chris, very interesting. I have a ground mounted Butternut with a radial plate and wire radials like you describe in your article, I have tried many things to reduce the noise on 20/30/40/80m but without much success. I’m sure most of this is being coupled into my current ground system from the local houses.

I have a 10x10m garden so I might experiment with some loops of different sizes. A couple of questions:

1) Did you completely disconnect the ground radial system and replace it with the loop(s)?
2) The Butternut has a matching stub for 20m in the feedline back to the shack, I’m not sure if this would now work as it is isolated from the ground side of the antenna...

I like the isolation and protection on the ground side. I will need to give this a bit more thought as to how I could try it with my current installation. 

Thanks again for sharing your ideas. Great work
Will
2E0WCJ


Will Grocott
 

Chris
Is there any advantage/disadvantage to adding more loops? The Radcom article had 2 or 3 loops of different sizes. Did you see any change in performance when you added loops or made them different sizes/orientation?

Thanks
Will
2E0WCJ


Simon
 

I am interested if this works on a vertical, say 1/4 for 40m
If so i would imagine it requires many many loops.
A traditional gnd system as i have here is more the better..i have 32 radials of different lenghts buried in the gnd.
Vertical is no longer up, but on tx it was very good , rx unuseable due to noise..


Simon
 

Though ..

Being as most man made rf is vertically polarised, I dont see how this would benefit a vertical antenna to any great extent, espically if the radials are already in the gnd shielded from rf noise..( as in burying ones coax to do the same.( good practice if possible.)

Not having seen the article probably missing something truly obvious!!

Chris??

Regards Simon

On 20 Sep 2020, at 13:01, Simon via groups.io <ohhellnotagain=gmail.com@groups.io> wrote:

I am interested if this works on a vertical, say 1/4 for 40m
If so i would imagine it requires many many loops.
A traditional gnd system as i have here is more the better..i have 32 radials of different lenghts buried in the gnd.
Vertical is no longer up, but on tx it was very good , rx unuseable due to noise..




Chris Moulding
 

I've just got back from holiday so I can answer questions more easily rather than relying on a very dodgy internet connection.

Answers to recent questions...

1) Can it be used with a 40m vertical?

Yes. The vertical antenna in the article is a G7FEK multiband vertical with a 1/4 wave section for 40m.

2) Is there and advantage in adding more loops?

Yes, I only had two loops to test the idea at both home and workshop locations. I tried an extra overlapping loop to prove that it improved performance.

3) I already have 32 buried radials...

Try connecting the ends of adjacent radials together to reduce the capacitive coupling to nearby electrical wiring.

4) A vertical antenna is noisy!

From the work I've done over many years I've proved that it's not the vertical element that picks up local RF noise, it's the capacitive coupling from the ends of the radials or straight counterpoises even if they are buried.

Unless you live on seawater or a saltwater swamp the ground has a relatively high resistance and RF at HF will penetrate several metres into the ground. The Beverage antenna uses this fact and that the speed of the wavefront is different in air and in ground. The wavefront starts to slope at the air/ground junction (surface of the ground). This allows a vertically polarised wave to couple to a horizontal wire.

Laying a horizontal wire on the ground forms a version of the Beverage antenna (Beverage on the Ground). This has slightly higher loss than the typical Beverage antenna mounted 1 or 2m above ground but still forms an excellent directional low noise HF antenna.

Laying radials and coax in the ground unless they are several metres deep or in saltwater does not shield the antenna from noise as much as would be expected or hoped.

If anyone wants to study this in greater detail I've collected all Harold Beverage's articles and patents from 1921 to 1923 and have links to them from a web page of some work on Beverage antennas I did two years ago:

http://www.crosscountrywireless.net/beverage_antenna_amplifier.htm

Regards,

Chris


Regards,

Chris


Simon
 

Chris any chance of an email with the article in?

Simon


Will Grocott
 

Hi Chris
just wanted to let you know I have completed the install everything is working like a charm. I made a coax pigtail so I could connect the isolator inline between my feeder and the butternut 20m matching stub. 


Super pleased and knowing I have isolation on the ground reassures me. I have a PME property and I can rest easy knowing my station won’t pass high current in a mains fault condition. Great work! 


Will, 2E0WCJ.