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 HF Noise Floor 
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Post Re: HF Noise Floor
G4LNA wrote:
You are using a balanced antenna, so the additional earthing would have no affect whatsoever. Just be careful with earth rods, you might create an electrical hazard by providing parallel earth paths with the mains safety earth. It's best to remove the earth rod system and rely on the electrical safety earth.

Keep safe mate.


Assume that this is due to the negative pole on the power supply being coupled to the mains earth?


Thu Aug 30, 2018 12:36 pm
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 HF Noise Floor 
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Without going too deeply into it, on certain types of supply system it can create a hazard under fault conditions, plus, if you make your earthing system have a lower impedance than the electrical supply one, electricity being lazy it's going to take the path of least resistance, the earth system is feeding the whole street, guess what's going to happen if a live to earth fault occurs somewhere along the street.....

It's much better to fit radials or counterpoises totally isolated from the electrical earth, but in your case it isn't needed.

If you think you might be getting interference going up the coaxial and coupling to the antenna, it's best to choke it out with ferrite on the coaxial.

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Thu Aug 30, 2018 12:53 pm
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 HF Noise Floor 
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Many thanks for the information that all makes sense, I have now completely removed the shack earth.

I have taken a video again that explains all, of which, I am uploading to YouTube.....


Thu Aug 30, 2018 7:37 pm
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 HF Noise Floor 
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Here it is:

https://youtu.be/xPI4b0Dt8PQ


Thu Aug 30, 2018 8:58 pm
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 HF Noise Floor 
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YouTube had a "problem" so here is the working link:

https://youtu.be/J6Isjumam1U


Fri Aug 31, 2018 7:21 am
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 HF Noise Floor 
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Post Re: HF Noise Floor
What you are listening to sounds like just general band noise. I just tried mine on 20m with the SSB filter and I'm getting about the same noise levels as what you are getting, about S5 peaking S6 and I live in a semi rural area, so I don't get a lot of noise.
We are just about to go out shopping, but I'll post a video when we get back just to show you.

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Fri Aug 31, 2018 8:04 am
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 HF Noise Floor 
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Well that is good to know Paul, I thought it was worthwhile doing that video.

Maybe there is no issue at all in that case but I thought it is definitely worth raising. I have in the region of 25x Fair-rite type #31 mix clip on beads, is it worth clipping a load of these onto the feeder where it enters the shack, or making a choke using ferrite rings instead?


Fri Aug 31, 2018 10:39 am
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 HF Noise Floor 
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Post Re: HF Noise Floor
M6MVW wrote:
Well that is good to know Paul, I thought it was worthwhile doing that video.

Maybe there is no issue at all in that case but I thought it is definitely worth raising. I have in the region of 25x Fair-rite type #31 mix clip on beads, is it worth clipping a load of these onto the feeder where it enters the shack, or making a choke using ferrite rings instead?



Or even something like this:

https://www.nevadaradio.co.uk/amateur-radio/rf-filters/diamond-cmf-2000


Fri Aug 31, 2018 11:16 am
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 HF Noise Floor 
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Expensive!

Or make one of these for Ā£6.25
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The core is from Qubits that will do the job just as well. You can use UR58 for the windings, I only used the posh Teflon cable because of it's small size, I wanted it for a small box.
There probably isn't a need for all that ferrite you have used, but it will do no harm to incorporate it on the antenna feeder where it leaves the shack, it will eliminate common mode coming down the outside of the coaxial and stop any noise going up towards the antenna.

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Fri Aug 31, 2018 11:59 am
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 HF Noise Floor 
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This is the noise for here on 20m. It is about the same as yours.

https://www.youtube.com/watch?v=Mbv6a1YkP6I

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Fri Aug 31, 2018 12:59 pm
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 HF Noise Floor 
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G4LNA wrote:
This is the noise for here on 20m. It is about the same as yours.

https://www.youtube.com/watch?v=Mbv6a1YkP6I


Thanks Paul, perhaps there is a non-issue.

I will add a choke/1:1 balun at the shake end for good measure anyway.


Fri Aug 31, 2018 3:20 pm
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 HF Noise Floor 
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Lovely and quiet this morning, turned radio on and it is a S4 noise floor on 20m.


Sat Sep 08, 2018 8:55 am
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 HF Noise Floor 
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Post Re: HF Noise Floor
It only became an issue for me when I started to realise I was either struggling to copy stations calling me or not hearing them at all. I did various tests mainly using Hackgreen and other UK SDR's putting out calls or finding stations and comparing like for like. It's not scientific but you get idea sooner or later if what you think is 'normal' noise floor is actually normal or not.

In my case I found that my noise floor was too high, had been increasing over the years and I was missing a lot of weaker stations calling me. In the end I moved all my RX to a quieter locations about 300metres away down the field and recieve using an SDR and wireless bridge link back to the shack.


Sat Sep 15, 2018 8:52 pm
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