Date   

Re: SDR-4+ Special Edition SDR receiver,

Kofi & Mimi in Ghana
 

Thanks you Roger for the information.
Kofi


Re: SDR-4+ Special Edition SDR receiver,

Roger Need
 

The SDR4+ is now listed as a discontinued product on the CCW site.

Roger


Re: Antenna Isolator install

Simon
 

Chris any chance of an email with the article in?

Simon


SDR-4+ Special Edition SDR receiver,

Kofi & Mimi in Ghana
 

Hi

After reading about the SDR-4+ Special Edition SDR receiver, I am tempted to place an order but am just wondering if all the good things said about it are real. Has anyone in this group ever use one. Will you recommend it?
Kofi


Re: Antenna Isolator install

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


Re: Antenna Isolator install

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..




Re: Antenna Isolator install

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..


Re: Antenna Isolator install

Will, M0LGW
 

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


Re: Considering the active antenna for SWL (comments from forum members)

David Cutter
 

John

End fed wire to loop with  proper common mode treatment will be night and day, but don't just look for signal level comparison, the aim of the game is signal to noise ratio.  The SW8 should easily add as much gain as you need without bringing in more noise. 

David 

G3UNA


On 19 September 2020 at 22:18 John Miller <aksafety@...> wrote:

I am considering purchasing the CCW active antenna for SWL. I’ve owned a Dressler ARA-60 years ago and it was excellent.

Any comments on reception, quality and mounting parameters would be most appreciated prior to me buying. I’m considering mounting to a fence adjacent to our home.

Right now I’m using a across the peak of the roof 65 ft end fed LW with a 9:1 balun on my Drake SW-8 which works well.

--
73

John


Considering the active antenna for SWL (comments from forum members)

John Miller <aksafety@...>
 

I am considering purchasing the CCW active antenna for SWL. I’ve owned a Dressler ARA-60 years ago and it was excellent.

Any comments on reception, quality and mounting parameters would be most appreciated prior to me buying. I’m considering mounting to a fence adjacent to our home.

Right now I’m using a across the peak of the roof 65 ft end fed LW with a 9:1 balun on my Drake SW-8 which works well.

--
73

John


Re: [SPAM]Re: [CrossCountryWireless] Antenna Isolator install

Will, M0LGW
 

Thank you Chris.
I’ve placed my order and I look forward to seeing it installed and working. I’ll take some measurements and let you know how it goes.

Thanks
Will
2E0WCJ

On 19 Sep 2020, at 20:55, Simon <ohhellnotagain@gmail.com> wrote:

Hi Chris

What was the antenna being used on hf?

Simon

On 19 Sep 2020, at 19:41, Chris Moulding <chrism@crosscountrywireless.net> wrote:

It's a combination of a few factors.

I found that using two or more loop counterpoises isolated from the ground greatly reduced capacitive coupling to nearby electrical systems compared to radials and straight counterpoises.

The isolation transformer is used to isolate the antenna and loop counterpoises from the incoming co-ax feed that will be connected to a RF noisy electrical ground at the transceiver.

Using both together reduces the noise floor dramatically as I show in the table in the article showing the measured noise levels across the HF bands.

What I couldn't add to the article is that two weeks ago we had a power cut where a digger cut the supply cable to the local substation. All power in the surrounding area had gone so I used the opportunity to use a 12 V battery to measure the HF noise levels and compare it again when the power came back on. There was only 1 or 2 dB difference in noise level between everything in the local area being off or on so it is really effective at reducing local RF noise.

A loop counterpoise can also be used to improve the performance of a static mobile installation as it increases the capacitance to ground over the vehicle body to ground capacitance. In that situation it doesn't need the isolation transformer as the vehicle is isolated from ground by the tyres.

Regards,

Chris

On 19 Sep 2020, at 18:42, Bob G3REP via groups.io <rparkes197=aol.com@groups.io> wrote:
Could the difference be a result of using isolating transformer you used as per your diagram. That is assuming you did not have it in place with the grounded vertical ?

Or did I miss something in the detail?
73s
Bob
G3REP












Re: [SPAM]Re: [CrossCountryWireless] Antenna Isolator install

Simon
 

Hi Chris

What was the antenna being used on hf?

Simon

On 19 Sep 2020, at 19:41, Chris Moulding <chrism@crosscountrywireless.net> wrote:

It's a combination of a few factors.

I found that using two or more loop counterpoises isolated from the ground greatly reduced capacitive coupling to nearby electrical systems compared to radials and straight counterpoises.

The isolation transformer is used to isolate the antenna and loop counterpoises from the incoming co-ax feed that will be connected to a RF noisy electrical ground at the transceiver.

Using both together reduces the noise floor dramatically as I show in the table in the article showing the measured noise levels across the HF bands.

What I couldn't add to the article is that two weeks ago we had a power cut where a digger cut the supply cable to the local substation. All power in the surrounding area had gone so I used the opportunity to use a 12 V battery to measure the HF noise levels and compare it again when the power came back on. There was only 1 or 2 dB difference in noise level between everything in the local area being off or on so it is really effective at reducing local RF noise.

A loop counterpoise can also be used to improve the performance of a static mobile installation as it increases the capacitance to ground over the vehicle body to ground capacitance. In that situation it doesn't need the isolation transformer as the vehicle is isolated from ground by the tyres.

Regards,

Chris

On 19 Sep 2020, at 18:42, Bob G3REP via groups.io <rparkes197=aol.com@groups.io> wrote:

Could the difference be a result of using isolating transformer you used as per your diagram. That is assuming you did not have it in place with the grounded vertical ?

Or did I miss something in the detail?
73s
Bob
G3REP









Re: [SPAM]Re: [CrossCountryWireless] Antenna Isolator install

Chris Moulding
 

It's a combination of a few factors.

I found that using two or more loop counterpoises isolated from the ground greatly reduced capacitive coupling to nearby electrical systems compared to radials and straight counterpoises.

The isolation transformer is used to isolate the antenna and loop counterpoises from the incoming co-ax feed that will be connected to a RF noisy electrical ground at the transceiver.

Using both together reduces the noise floor dramatically as I show in the table in the article showing the measured noise levels across the HF bands.

What I couldn't add to the article is that two weeks ago we had a power cut where a digger cut the supply cable to the local substation. All power in the surrounding area had gone so I used the opportunity to use a 12 V battery to measure the HF noise levels and compare it again when the power came back on. There was only 1 or 2 dB difference in noise level between everything in the local area being off or on so it is really effective at reducing local RF noise.

A loop counterpoise can also be used to improve the performance of a static mobile installation as it increases the capacitance to ground over the vehicle body to ground capacitance. In that situation it doesn't need the isolation transformer as the vehicle is isolated from ground by the tyres.

Regards,

Chris

On 19 Sep 2020, at 18:42, Bob G3REP via groups.io <rparkes197=aol.com@groups.io> wrote:

Could the difference be a result of using isolating transformer you used as per your diagram. That is assuming you did not have it in place with the grounded vertical ?

Or did I miss something in the detail?
73s
Bob
G3REP





Re: [SPAM]Re: [CrossCountryWireless] Antenna Isolator install

Bob G3REP
 

Could the difference be a result of using isolating transformer you used as per your diagram. That is assuming you did not have it in place with the grounded vertical ?

Or did I miss something in the detail?
73s
Bob
G3REP


Re: [SPAM]Re: [CrossCountryWireless] Antenna Isolator install

Chris Moulding
 

Disconnecting the existing ground system would work OK.

Regards,

Chris

On 19 Sep 2020, at 12:01, Simon <ohhellnotagain@gmail.com> wrote:

Hi Chris..any chance of a copy?please..

Question..you say remove existing gnd system..this by disconnecting ( easy) or digging up? ( impossible.)







Re: [SPAM]Re: [CrossCountryWireless] Antenna Isolator install

Simon
 

Hi Chris..any chance of a copy?please..

Question..you say remove existing gnd system..this by disconnecting ( easy) or digging up? ( impossible.)


Re: [SPAM]Re: [CrossCountryWireless] Antenna Isolator install

Chris Moulding
 

The antenna and loop counterpoises are isolated from ground. The wire in the loop counterpoises is insulated and is laid directly on the ground to couple capacitively to ground.

The existing ground radial system was removed and replaced with the loop counterpoises.

If you were to use or follow the transformer design with the capacitors to counteract leakage inductance in the transformer it has an excellent match to 50 ohms so would work with the matching stub on your feeder. If you have already spent a lot of time optimising the tuning of a multiband vertical the transformer can be connected in circuit with very little difference needed to the antenna tuning. There were no changes needed on the two antennas I built to test the design.

Regards,

Chris


On 19 Sep 2020, at 11:25, Will Grocott <wjcgrocott@...> wrote:



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


Re: Antenna Isolator install

Will, M0LGW
 

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


Re: Antenna Isolator install

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


Re: Antenna Isolator install

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

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