RFI noise mitigation

[ke0me]

On Hamnation episode 239, they mentioned a RFI solution using a counterpoise.

The ham in question lived on a second floor, so an earth ground lead was a difficult proposition.
His solution was to make an accurately measured 1/4 wave wire counterpoise connected to the ground lead of the radio.

that solved his rfi problem. Question is, would that possibly help the S9 noise level I'm getting on my 2nd floor apartment?

[NN5I]

Question is, would that possibly help the S9 noise level I'm getting on my 2nd floor apartment?

It depends on the source of the noise.

I have known hams who got rid of S9 noise in various ways. One had a serious noise problem that went away when someone (unknown :whistle:) mysteriously poisoned his neighbor's dog. Another had to pay a divorce lawyer, but eventually got rid of the noise.

If your noise is electrical, a counterpoise may help, or not. You can determine an answer experimentally, at small cost and small effort. Buy 17 feet of wire (I'm assuming you have the noise on 20 meters) and strip one end. Then screw it down on the ground terminal. Then listen. My next-door neighbor's grandkid could do that, and she's only four. But I think she'd have trouble paying the two bucks or so for the wire.

[Radio]

I am blessed that my home shack is in the basement.

But, I had a major reduction in noise when I grounded all of my equipment together with short pieces of coax braid I had salvaged and made into straps. These were connected by hose clamps to a copper pipe that runs the length of the radio table. Then earth ground is connected to the pipe. This is all in the ARRL Operators Manual.

Also, vertical antennas are inherently noisy, because a lot of noise is vertically polarized, such as lightning.

You might do a little Sherlock Holmes thing. I found several older computers that were spewing noise via mouse and keyboard cables. Used ferrite blocks to cure that. Try listening to the noise while turning off stuff in the apartment. You'd be surprised what could be making noise.

[ke0me]

Carl,

Oops, yes, this is electrical noise.
I know its not the dog, he more resembles a dirty mop than a noise generator ( unless someone knocks at the door).

My original guess is that the noise is due to poor/non-exisitent ground. However, since we are in the apartment only until the end of May, I want to focus on working on the RV grounding as primary. The apartment station is very temporary, so its more of a spare time activity until we get back on the road.

I will try isolating the other electrical equipment and installing a counterpoise and see if those make any improvement.

[ke0me]

I forgot to mention, all the individual components (radio, PS, tuner, etc) are grounded individually to a grounding bar in the "radio box", then one ground lead to the hot water heating system copper pipe, which is the only ground I can find at present.

[NN5I]

... the hot water heating system copper pipe, which is the only ground I can find at present.

Don't forget the third wire (safety ground) in an outlet. It may be what you need - and maybe not.

You can find out whether that copper pipe is grounded by measuring the resistance between it and the safety ground. First, though, measure voltage between them, just to be sure you won't zap the ohmmeter if the outlet is miswired, which sometimes it is..

[ke0me]

Carl,

Tnx, I'll add that to the list of things to do.

The apartment was built in the 1970's, so I will start seeing what they have for basic wiring.

I do notice they have done some upgrades, like GFI outlets in bath and kitchen, so maybe its adequate.

PS- just like at campgrounds, I checked each outlet with my 3-light tester to verify the wiring polarity and ground connection, all was OK.

[wa8yxm]

Question is, would that possibly help the S9 noise level I'm getting on my 2nd floor apartment?

As asked... There can be only one answer.. YES it POSSIBLY might help.

However that is not a guarantee. Depends on the source of the noise... For example.. I recall the ham who was staying for a time across from the Hotel Dixie.. Well a couple (3) letters had burned out on the sign so the big neon sign read Hotel D X.

Alas.. the sign was generating enough RFI so you could not hear yourself think radio wise on the upper floors.

[N3LYT]

I don't think an electrical ground would be a good choice you may end up with very unhappy neighbors.

[NN5I]

I don't think an electrical ground would be a good choice you may end up with very unhappy neighbors.

That's surely possible; it depends on the design of the electrical distribution in the building.

Maybe it depends on how well you like the neighbors.

[ke0me]

Well, I haven't met too many of the neighbors, most of them work, are gone early and back late.

However, someone is always burning "incense" or something as the same smell is always in the stairwell.

This is Colorado after all, perhaps they have a "medical condition" that requires them to smoke their "medication". Sarcasm intended.

So maybe they don't really care about a little RFI.

I operate very infrequently anyway, have been too busy with studying for Extra (glad that is done now!) and part time work.

So, now maybe I can relax a bit and operate during the day when most neighbors are gone to work.

[NN5I]

If the neighbors annoy by turning up their TVs too loud, and there's a community TV antenna system, you could cure that noise with about 100w of RF into the shared coax for a little while. But probably they're all on Comcast, and certainly you wouldn't want to wipe that out. Would you?;)

[Radio]

This is Colorado after all, perhaps they have a "medical condition" that requires them to smoke their "medication". Sarcasm intended.

So maybe they don't really care about a little RFI.

You think they wouldn't mind getting a little buzz on then? :hippy:

[ke0me]

2 things

I previously worked for "C", but not very long, we agreed to part ways amiably, they paid me money and I promised to never come back (called severance pay).

Right now, "C" is the only provider I could get for wired internet at the apartment for 6 months. The local phone company (name withheld) said they didn't have capacity at the node and didn't feel like going to any expense to serve me. They are noted for their customer service.

So for TV reception, we either go to the kids house who have the big expensive cable package, or use the amplified antenna I bought at Target to receive a few channels, all of which are at least 40-60 miles away.

[wa8yxm]

Grounds.. Bob heil often puts adapters on his equipment plug so he can "lift" the safety ground... George Thomas adds Grounding straps (Wide copper straps) to a common bus to earth ground.

Two differeing viewpoints... I believe in a single ground for all hardware, No loops.

[ke0me]

in traditional telecom offices, the ground system was "star", i.e. all grounds ran separately to a single point ground, and the ground field was installed and tested to meet a required standard with a ground resistance test unit by Megger (current price $843). Never did the test myself, but saw it performed several times.

However, if it was considered a "radio site", then it had a ground halo ring around the ceiling of the radio area, with multiple grounds fields outside.

If I recall, the instructions for grounding were probably about 200 pages long of how to perform all the required work.

I don't plan to go to the same extent as that (and I can't afford it either).

My feeling is that you need to be consistent in the method you apply, and test the result one change at a time (as noted earlier).

[NN5I]

with a ground resistance test unit by Megger

That seems strange. Every Megger I ever saw was a device for measuring very high resistances (many megohms -- thus the name Megger). I don't see what use they'd be in measuring the low resistances of ground systems.

I owned a Megger for a number of years, but a few years ago I gave it to an old friend (Jim Haynie, W5JBP, a former president of ARRL and a good guy), who probably still has it. I hadn't used it in a long time, and Jim had an immediate use for it.

[ke0me]

For those not familiar with the brand name, here is info from the website:
megger.us

For over 100 years, Megger has been the premier provider of electric test equipment and measuring instruments for electrical power applications. The company was founded in 1889 in England as Evershed & Vignoles and over the years has been known by several names, most recently, AVO International. In 2002, the company decided to change its name to Megger, which is what many people have called it all along. Today, Megger enjoys an outstanding reputation in the areas of insulation testing, low resistance and ground resistance testing, and a wide variety of electrical contractor maintenance tools such as multimeters, portable appliance testers and clamp-on meters.

So, they cover the spectrum from low resistance to high, hence the nickname "megger" as related to the testing done.

[NN5I]

Good old ORR. Learn a new truth every other day, and in the in-between days find out that what I've known for decades ain't so.

[ke0me]

After suffering for many months trying to intermittently tackle my S9 noise problem, I'm taking a step back.

I want to try to identify what type of noise it is , where it's coming from, and do a thorough and systematic process to eliminate it.

Station- IC-7200, Alinco dmv-330 power supply, tvi filter, MFJ tuner
Each piece has a ground lead from the ground terminal to a common ground point, then that point goes on a single wire to the outside ground, a 4 ft copper ground rod.

I'm in a ground floor apartment right now, the ground run is about 10-12 ft from radio to rod.

Power supply ac cable has snap on Toroid filters installed

The noise sounds like a constant "static" at S-9 to 20 over.( with all noise filters and blankers ON)
All the time
All hf bands
Inside the rv
Outside the rv
Inside 2 different apartments
Using long wire antenna
Using Alpha vertical on tripod
Using tar heel II mounted on balcony

Random ideas ( some will seem strange) tried with no success:
Used 2 prong plug in AC outlet
Turned off cable modem, phone chargers
Turned off fluorescent and led lites
Lifted ground from ground rod, no change!

At this point I'm getting frustrated.

Would appreciate any suggestions to start identifying where noise comes from.

[wa8yxm]

Thinking on this some more. The RFI problem the ham had on HN was his own RF getting back into the Shack's Audio and causing distortion.

The reason was the lack of the "Other half" of his antenna (The counterpoise) forced the Coax and Radio to assume that duty. which it did badly.

For your RECEIVED noise problem.. It might make a 3DB (1/2 S-unit) INCREASE (And by the way increase signals received by the same amount) or not

I have seen some strange things when dealing with received noise... For example.. I designed a double-j-pole (There is a name for this butr I forget what it is, it is a form of colinier array but fed at the phasing stub, not the end) worked great but if I put the shield at the "U" on teh phasing harness (Fed it as unbalanced) the noise was increadable.. Putting the shield directly across from the center wire (Balanced) no noise.

[ke0me]

A glimmer of hope

I looked at what I had that I could try without buying anything.

I had several MFJ-701 snap-on ferrite Toroid chokes left over from my first attempt at noise reduction from the ac power line.

So I went from 3 turns on one choke to 2 turns on 4 chokes.

It my be my wishful thinking, but on 40 meters (the only band the long wire seems to load on nicely) I thought I saw a 2 S unit drop in average noise.

Where it was peaking S-9 to 20 over, it now seems to be peaking S-7 to 9.

I need band conditions to get better so I can actually hear some signals!

Now I'm wondering if another set of 4 chokes on the ac line will make much of an incremental difference.

The big assumption is that the noise is coming from ac line and not other places.

Thoughts please.

[wa8yxm]

I too do not care for the 3rd wire ground on an outlet for one thing if it is GFCI protected it may be a phantom ground. (often those are not grounded)

And a heating system pipe is another poor choice.. Unless you have tested and verified.

On receive, Noise comes in one of three ways
ON the power line
ON the antenna
Generated internally in the radio.

You need to find out where it's coming from..

[N3LYT]

Have you contacted the power Co.? I'm wondering if you don't have a power line issue and it's not even in the house. Cracked insulator will do it every time. On the topic of meggers I have an old crank type and it does a very good job of harvesting fishing worms.

[ke0me]

Oh my gosh does that bring back memories.

Back in the 60's my parents took us to Minnesota (from Kansas City) for a fishing vacation every summer.

My dad had a hand crank generator, which he used to "excite " the local earthworms from the ground .

We would collect them, feed them for a couple of weeks, and then ship the worms in a box covered in ice in the trunk of the car 600 miles.

So, I guess those Missouri worms caught fish better than the native Minnesota worms.

[WinnySud]

Hi..i am a new user here. In my case I had a major reduction in noise when I grounded all of my equipment together with short pieces of coax braid I had salvaged and made into straps. These were connected by hose clamps to a copper pipe that runs the length of the radio table. Then earth ground is connected to the pipe. This is all in the ARRL Operators Manual. And vertical antennas are inherently noisy, because a lot of noise is vertically polarized, such as lightning.

[NN5I]

Is it coming in on the antenna? Disconnect antenna to find out. Is it coming on power (ac) connection? Run on battery to find out, or on a known quiet inverter fed from a battery.

If you have a handheld that can listen on MF and HF, walk around with it a bit. Most, or at least many, modern VHF and UHF handhelds have wide-range receivers.

Stuff like that, which probably you already tried but didn't mention recently.

[NN5I]

Back in the 60's my parents took us to Minnesota (from Kansas City) for a fishing vacation every summer.

My dad had a hand crank generator, which he used to "excite " the local earthworms from the ground.

I guess your Dad's callsign must have been w0rms.

[ke0me]

good joke.

actually only my brother and I were licensed. And one cousin is St. Louis.

That's about it for hams in the family.

[Radio]

According to QRZ.com:

W0RMS

Ernest S Chiles, II
114 Sunrise Dr
Jackson, MO 63755
USA

:rofl:

I used to be N4FIG. Got tired of being "Mr Figgy" on the repeater. And people thought my amateur radio plate was an acronym for something and were always trying to figure out what it meant. :radio:

[NN5I]

My first callsign was K4SCK and I wrote it all over my schoolbooks. Then the other high-school kids told me what they thought it meant. Back then (1950s) you couldn't change your callsign, either.

[ke0me]

I have had 5 calls, in this order
WN0OHI
WA0OHI
WB9IYK - the worst!! Dx stations can't understand the "y" with any phonetic I used.
KD9LG
And then by random chance when I moved to Kansas in 1995 the FCC assigned me,
KE0ME
I liked that for phonetics and CW so that's what we will keep.
Did not choose a vanity call when upgraded to extra this year, I like what I have.

[NN5I]

Worst callsign I ever knew of, for CW anyway, belonged to an acquaintance in the Dallas area in the early 1980s. John Slaughter's call was WB5HSI. He never worked CW, and who could blame him?

It's almost as bad as trying to tell someone (on CW) that you're in Tallahassee.

[ke0me]

When I was first licensed, I lived in Independence, Missouri.

Seems like it took forever to send that at 5 wpm.

[ke0me]

As noted, have been fighting a "static" noise issue on and off over the last year or so.

Last week I was making the wiring neater inside the box where I have the radio, ps, tuner, etc mounted.

I reduced the dc power cord from power supply to radio from the 10 ft standard length (all tangled and stuffed into the box) to a mostly direct 15-18 inch run.

Magic, almost all the noise disappeared😀

So, is this the solution to most of my noise problem? I sure hope so!

[NN5I]

Dick, is that a switching power supply? I strongly suspect you've found the source of much noise.

Wrap that DC cord a couple turns through a big mix 31 ferrite. Do the same (with another mix 31 ferrite, not the same one) with the AC supply cord that feeds the power supply (and shorten that cord too, if you can).

Very low cost, easy to do, can't hurt anything, and has a good chance of helping.

[N3LYT]

Could also become an antenna picking up noise. Can you run this thing with a battery for a test? I have never had issues with modern switchers even my camper switcher is quiet. Older ones yeah they worn't much. I have had more noise problems with switching supplies in 12V LED's

[ke0me]

Thanks for the replies.

I have already wound the AC input cord with chokes a few months ago, and it seemed to make a bit of an improvement.(2 s-units)

The shorter DC cable made a whale of a difference. Like 7 S-units.

Yes, its a switching supply, Alinco DMV-330. Has good ratings on EHAM for not producing noise, but I am assuming the longer power cord was a great pickup antenna for what noise there was.

Anyway, if this info helps someone else with their issues, that's what we are here for.

[ke0me]

Just saw the other post.

Yes, its super quiet on battery, I just never put the cord length as a source of noise.

Anyway, yes it is a LOT quieter now, except on 40, which seems to be always noisy.

[LulaNord]

Hi...i am a new user here. As per my knowledge If your noise is electrical, a counterpoise may help, or not. You can determine an answer experimentally, at small cost and small effort. Buy 17 feet of wire and strip one end. Then screw it down on the ground terminal. Then listen. My next-door neighbor's grandkid could do that, and she's only four.

[Radio]

Welcome aboard Lula. :hisign:

[NN5I]

Welcome aboard, Lula. [Boy, that comma really changes the meaning --]

You'll find us a friendly group, with occasional ribbing.

[BeachGeezer]

Was this solved?

[NN5I]

[QUOTE=ke0me;14823]The apartment was built in the 1970's, so I will start seeing what they have for basic wiring./QUOTE]

Incidentally, many 70s-vintage buildings were wired with aluminum wires. These can become really RF-noisy when they corrode even invisibly; and the plug-in wiring tester may still say all is hunky-dory.