RFI noise mitigation

[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]

Originally Posted by ke0me

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



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.

[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.