Baseline hiss/noise pick up on antennas

[KD6RF]

VKRules is absolutely correct.

Again, if a choke changes your SWR, that is absolute PROOF of common mode current.

That necessarily means that your entire length of coax is now an unwanted part of your antenna, picking up nose from anything and everything it comes near.

Naturally, you first want to make sure that nothing is broken and your unit is intact, then address the radiating coax issue.

Imax is known for this problem, and omitting the choke to get a low SWR is a bandaid that comes along with a distorted radiation pattern, loss, and noise pickup.

There are various threads around where people add radials to fix the high SWR problem and keeping nasty sneaky common mode curent off of the coax shield.

 

[Captain Kilowatt]

Absolutely. When I say station grounds I start at the antenna. On a three sided mast that means three heavy duty grounds that start at the antenna and attach to three separate 8ft ground rods hammered in to the soil. Inside the shack you still need equipment grounds and not just house grounds either. Some house grounds are not all that great, and if you have GFCI breakers or outlets you can be tripping those.

Done to MIL-STD 1686

Exactly. A station ground is not necessarily a single ground but rather a single point ground. The antenna lightning ground, the electrical service ground, and the shack safety ground are all PART of a station ground. Anyone that says a station ground is for the clueless or lazy does not understand just what a station ground is. Tell a broadcast engineer his AM site does not need a station ground and he will chase them down and beat them with a ground rod.

 

[543_Dallas]

A station ground is important for lightning and safety. Sometimes these clueless or lazy people install grounds for the wrong reasons. Like trying to fix high SWR or common mode issues.

The AM engineer might have an extensive radial system under the tower too. He does it for good reason. The CBER on 27mhz that does the same thing with a ground plane on a 30 ft tower is wasting resources.

 

[M0GVZ]

Exactly. A station ground is not necessarily a single ground but rather a single point ground. The antenna lightning ground, the electrical service ground, and the shack safety ground are all PART of a station ground. Anyone that says a station ground is for the clueless or lazy does not understand just what a station ground is. Tell a broadcast engineer his AM site does not need a station ground and he will chase them down and beat them with a ground rod.

They are three separate things. You have a ground for RF, a ground for lightning and a ground for electrical safety. You do not mix those things otherwise you can end up with RF on the mains electrics getting into all the household gadgets or you can end up with everything in the house getting a blast in the event of a lightning strike or if you connect that little earth tab onto a ground wire which is also connected to the electrical safety ground you can end up with full AC mains voltage on the cases of your radio gear if you get a fault on an appliance in the house.

When Amateurs and CBers talk about a station ground they're invariably talking about piling a ground rod into the ground and connecting it via braid/wire/copper bus bar to the earth tabs on their radios/amps etc to act as a RF ground. That is not where you do your RF grounding, that is done at the antenna. Hence the comment about it being the lazy option.

 

[The DB]

They are three separate things. You have a ground for RF, a ground for lightning and a ground for electrical safety. You do not mix those things...

You are half right, there are three different ground systems in play and each has their own requirements. However, "mixing" is the wrong word here. To be properly grounded, they must be connected together. Although, I do know that over in your neck of the world there are some, usually newer, houses with floating ground systems that aren't directly earthed, so in your case there may be some differences. While familiar with the concept, I have no direct experience working with such systems.

otherwise you can end up with RF on the mains electrics getting into all the household gadgets

Not if you build the system properly. Just because there is a connection to an RF ground does not automagically mean RF will get into your other ground systems. As a matter of fact, is you connect them properly there is no danger of such a problem.

or you can end up with everything in the house getting a blast in the event of a lightning strike

This is widely believed, but actually not correct either. If everything in your house is connected to a proper earth ground, then everything in the house will be at a common potential. The floating ground systems that some houses in your area have are actually based on this very concept, even if they are not at earth potential they are at the same potential. The reference (aka ground) being at the same potential is the key to lightening safety.

or if you connect that little earth tab onto a ground wire which is also connected to the electrical safety ground you can end up with full AC mains voltage on the cases of your radio gear if you get a fault on an appliance in the house.

If you hook it up properly, there is no danger of AC mains voltage on the case of your radio gear. Why would you hook up a hot lead to a ground anyway are you trying to cause damage? Here in the states, the neutral wire is hooked up to an earth ground where the electrical circuit enters the house. This so called dangerous setup is standard procedure, and if it isn't done the person who didn't do it can be sued for violating electrical safety practices...

When Amateurs and CBers talk about a station ground they're invariably talking about piling a ground rod into the ground and connecting it via braid/wire/copper bus bar to the earth tabs on their radios/amps etc to act as a RF ground. That is not where you do your RF grounding, that is done at the antenna. Hence the comment about it being the lazy option.

In most setups there is a direct DC connection between this RF ground you mentioned, and at least one other ground system, even if you didn't directly run a wire for this purpose yourself...

 

[Captain Kilowatt]

They are three separate things. You have a ground for RF, a ground for lightning and a ground for electrical safety. You do not mix those things otherwise you can end up with RF on the mains electrics getting into all the household gadgets or you can end up with everything in the house getting a blast in the event of a lightning strike or if you connect that little earth tab onto a ground wire which is also connected to the electrical safety ground you can end up with full AC mains voltage on the cases of your radio gear if you get a fault on an appliance in the house.

When Amateurs and CBers talk about a station ground they're invariably talking about piling a ground rod into the ground and connecting it via braid/wire/copper bus bar to the earth tabs on their radios/amps etc to act as a RF ground. That is not where you do your RF grounding, that is done at the antenna. Hence the comment about it being the lazy option.

Connor, thank you for confirming the part where I said "Anyone that says a station ground is for the clueless or lazy does not understand just what a station ground is." I stand by what I said about just WHAT a station ground is. It is the single point ground where you ground your station. The electrical ground from your service entrance should also connect to that point as well as any other grounds. That single point is what prevents such things as ground loops that cause issues.

When you say "When Amateurs and CBers talk about a station ground they're invariably talking about piling a ground rod into the ground and connecting it via braid/wire/copper bus bar to the earth tabs on their radios/amps etc to act as a RF ground. " I in turn say that I cannot help it when other people use the improper terms to describe something. I will continue to use the proper terminology and not apologize for doing so. A station ground is not as you describe regardless of how many people think it is. On that we both agree however on what constitutes a STATION ground we seem to be in disagreement. I will continue to bond my electrical service entrance ground to my safety ground(usually the same thing over here) and also my RF ground and lightning ground systems all together but do it in ONE place only and THAT point becomes what is known as a station ground. It's the way we do it in commercial and broadcast installations here and we take many hits directly from lightning without damage and even the 50Kw AM stations with mod peaks of >200Kw don't cause havoc on the power distribution systems if things are done properly.

 

[Captain Kilowatt]

This is widely believed, but actually not correct either. If everything in your house is connected to a proper earth ground, then everything in the house will be at a common potential. The floating ground systems that some houses in your area have are actually based on this very concept, even if they are not at earth potential they are at the same potential. The reference (aka ground) being at the same potential is the key to lightening safety.

Exactly. The common ground point actually raises in electrical potential with a strike and because there is one and ONLY one ground point everything is at the same potential and as such no current flows from one ground to another ground which is an equipment killer. Broadcast transmitters are actually installed with their chassis raised off the concrete floors in the TX houses to remove that path to ground and preserve the single point ground.

If you hook it up properly, there is no danger of AC mains voltage on the case of your radio gear. Why would you hook up a hot lead to a ground anyway are you trying to cause damage? Here in the states, the neutral wire is hooked up to an earth ground where the electrical circuit enters the house. This so called dangerous setup is standard procedure, and if it isn't done the person who didn't do it can be sued for violating electrical safety practices...

We have to remember (and perhaps Connor forgets) that he and we have different electrical systems. His normal household mains voltage is 240 volts with both sides hot whereas we are 120 volts one side hot with the other side neutral which is tied to the safety ground back at the panel.

In most setups there is a direct DC connection between this RF ground you mentioned, and at least one other ground system, even if you didn't directly run a wire for this purpose yourself...

 

[The DB]

We have to remember (and perhaps Connor forgets) that he and we have different electrical systems. His normal household mains voltage is 240 volts with both sides hot whereas we are 120 volts one side hot with the other side neutral which is tied to the safety ground back at the panel.

You might be correct. I was unaware that they wouldn't have a neutral lead along with their two hot leads like the three wire drops we have here in the states. I'm not entirely sure how such a system would be affected by the addition of a ground and a lightening hit as it is different from the systems used here. If I didn't monitor a UK based forum I wouldn't have known about such systems at all.

I wonder if the lack of a neutral lead is also likely part of the reason some newer houses over there have a floating ground system as opposed to a direct ground like we have here...

At this point, anything further on such systems before I look such info up would be speculation on my part so I'll refrain from continuing on that line of discussion.

Here in the states, there is one and only one way to set such a system up correctly, and is all of the grounds connected together.


The DB

 

[Captain Kilowatt]

You might be correct. I was unaware that they wouldn't have a neutral lead along with their two hot leads like the three wire drops we have here in the states. I'm not entirely sure how such a system would be affected by the addition of a ground and a lightening hit as it is different from the systems used here. If I didn't monitor a UK based forum I wouldn't have known about such systems at all.

I wonder if the lack of a neutral lead is also likely part of the reason some newer houses over there have a floating ground system as opposed to a direct ground like we have here...

At this point, anything further on such systems before I look such info up would be speculation on my part so I'll refrain from continuing on that line of discussion.

Here in the states, there is one and only one way to set such a system up correctly, and is all of the grounds connected together.


The DB

Actually I think I was in error when I said UK mains has both sides hot. I believe they have 240 volts hot along with a neutral and a ground (earth) wire which would make it the same as ours except for the higher voltage. One thing they do which is seldom found anywhere else in the world is install a ring circuit where the electrical lines leave the service entrance and run to various outlets etc and terminate back at the panel rather than simply stop at the last outlet. Sounds like the makings of a nice pick-up loop.

 

[Heavy Metal]

So 1 ground rod all equipment ect minus antenna is run to that single ground rod?

Also have had other say run 3' APPART attached to one another and more than one ground rod on ground and only 1 point all things are run to it to connect too? Is this still considered single ground point?



.
..
...
..
. Point of connection

 

[222DBFL]

You can run more than one ground rod. 3 at the base of the antenna mast or tower, spread apart about 3ft each with some good wire going to them. At least #6awg or larger, and all connected together. This will then go to another ground rod if needed of wanted for your equipment which will be connected to the other grounding rods to form a single point ground system. A ground buss bar is a good way to get all the grounds tied together. There are other methods and options. But yes all your grounds should be tied together forming a single ground point.
Hope this makes sense.

 

[Sonar]

Two words can make a huge difference, Station Grounds.

Do station ground really make a difference.
I've read yes, no and not important. I would like to properly ground my station but have absolutely no access to any water pipes and can't have any wires except my coax coming in through the seald single window in the room my setups in. Any suggestions or ideas would be appreciated.

 

[222DBFL]

Yes proper grounding is important. If it wasn't then why the heck do they ground every tower you see. And that grounding procedure is what should be followed. Research some into proper grounding of commercial towers and you will understand why it's important.
If you want to keep your station for any length of time, grounding is a must. JMHO.

 

[222DBFL]

Run a ground along side your coax and into your window. Same thing as I did. It's very important to have your entire radio base station grounded properly. That is why every tower you see around is grounded very well and some can take multiple direct lightning hits to the tower and still keep functioning. Even if your antenna gets hit and destroyed, with a proper ground system in place, you can avoid further damage to your equipment. Also even if you have all the necessary things needed to complete a grounding system, it's not a bad idea to unplug all your equipment, including coax and power from the wall. Just a little extra insurance. Keep the coax as far as you can from your radio equipment as well when it's unplugged. JMHO's. It's not a one day job type thing to do it properly, but it's well worth it!! Again, JMHO.

 

[222DBFL]

Also you can run a ground buss bar inside and like I said, just have 1 wire entering your room. They also make hatch plates for Windows that will do what you need. A piece of wood drilled out is another option. Paint it the same color as the window trim and it won't be so visible. Where there is a will there's always a way!!