grounding for RF

[ridgescan]

I have kind of a unique problem when it comes to grounding my antennas; I and my radios are on the third floor (about 25' up) and my antennas are on the roof right above me (about 35' up). I have been reading around that if I were to run too long a ground wire from the antennas all the way to the ground to either a waterpipe or a rod, that ground line could pick up RFI and send it to my radio. I now have a short wire connected from the antennas to a copper aerator pipe on the roof (I dont even know if there's continuity from that point to ground) What could I use up this high as a reliable RF ground? I get a TON of buzz 12khz and up, up to 15s!

 

[davidgcet]

unless the ground you connected to has a very low impedence to your electrical groudn you could be creating a ground loop and this is the buzz you hear. try disconnecting your antenna ground wire and see if the buzz goes away.

PROPER grounding is important, you cannot just "ground" to the nearest metallic thing to you.

 

[SCPD]

Ridge,

A cheap trick would be to go buy some chicken wire... you can usually get this stuff pretty cheap. Ideally, make several strips and connect them together to form a cheap wire/mesh ground screen.

If you have some roof space (even just 100ft sq) would make a cheap ground. This might help a bit.

OR

You could always invest in the Apex vertical. Use quality coax (LMR400 or RG8U) and put it up on a mast and you're in business: Apex Radio 303WA-2 Shortwave antenna. ApexRadio

(The vertical will help with noise.)

 

[ridgescan]

I ran a ground cable to the nearby fire escape-which is bolted to the I-beam frame of this building. This knocked about 6s-units of buzz off the noisefloor above 13khz. I can hear more signals up in the 15 and 17khz areas now. I seem to be on the right path. However I am picking up a bit more noise down low around 3-6khz. I will see later if this affected my evening listening.
So Nick I assume that running that long ground cable 35ft.down to a waterpipe is a bad idea? Gees Im getting a decent signal from Radio Australia on 17795khz now 9-12s

 

[SCPD]

This knocked about 6s-units of buzz off the noisefloor above 13khz. I can hear more signals up in the 15 and 17khz areas now. I seem to be on the right path. However I am picking up a bit more noise down low around 3-6khz. I will see later if this affected my evening listening.

I trust you mean Mhz?

So Nick I assume that running that long ground cable 35ft.down to a waterpipe is a bad idea? Gees Im getting a decent signal from Radio Australia on 17795khz now 9-12s

The fire escape is a good idea - use whatever works. But yes, you want to avoid a long ground run at all costs.

 

[ridgescan]

Yeah trust lazy typing.. Thanks Nick this seems to do for now. I wonder how that vertical you suggested performs-it's pretty short. I will look into it too.

 

[SCPD]

It's only 6ft but it has a matching section inside the base which likely adds length electrically. So it 'appears' to be much taller. Ideally, you would want to get it up high so it's at least 10ft above the roof. This ensures that it's well above the noise level. It would good coax for best performance.

 

[ampulman]

From a plumbing point of view, assuming that the waste piping is all metal, while it may be grounded, it is not bonded to the cold water pipe (which is [should be] bonded) to the service ground.

Experts in grounding, please chime in.

 

[ridgescan]

Yeah Nick I like the sound of that one-I still have my eye on that ef-swl too although my current setup has improved quite a bit after I properly grounded it yesterday. Now the weaker signals are presenting themselves like never before. As far as coax I run RG8X which I think will do, because it's only a 28' run to the antenna.
Ampulman- yeah I think you are right-especially since I know now that I wasnt well-grounded with that pipe judging by the performance I am getting now.