Noise, noise, noise....your opinion.

[W2DI]

Hi all;

I have a location with a great deal of noise. I've tried to locate the source and have come to the conclusion it is coming from several sources.

I have an Ft-817 (yea, one of those qrp gluttons for pain) with a G5RV JR over top of the home about 25' in the air.

I like working 40 (close in, not DX) and up, especially 17, when open.

I think the noise is very wide-band and probably coming from a few sources:
1. A 50KW AM digital station with a full 1/2 wave antenna about 1 mile away.
2. Computer noise - everyone in the home has a computer with wireless router in the mix
3. Cable TV noise.

On certain frequencies I can reach over S9 noise.

Here is my question. If the noise is coming form several sources, and I admit I don't know, I would assume a Noise canceling filter, AKA the MFJ-1206 or the (Timewave) ANC-4 would not help eliminate these sources. This type of filter is absolutely incredible - but only on one noise at a time. I had one and can't compliment the effectiveness enough. They are great, but only with one source.

Or should I try one of the outboard DSP filters such as the MFJ-784B. This is a Tunable DSP filter that has received very good reviews here on e-ham.

I know they are a little complicated to learn to use properly, but for the noise I seem to have, would anyone have an opinion on the effectiveness this may provide.

I don't want to move the antenna or get another (vertical) and move it out further away from the home. Radials and feel-line loss is a consideration (with a big-deal 5 watts I have a power envy as it is).

Anyway. Thanks for reading and any opinions especially on the 784B option are welcome. This is the best source of info on the net!!!!

Joe, w2di
NJ

[AD4U]

If at all possible it would be MUCH BETTER to locate and eliminate the noise at its source.  It can be done.  Noise blankers, noise limiters, DSP, etc only try to cover up the noise.  Some will disagree, but IMO these devices leave a lot to be desired.

The 50 KW AM station within a mile may be causing "front end" over load in your 817.  I have an 817 and the receiver is OK for its intended use, but it leaves a lot to be desired in many ways - strong signal environments is one.

Do you have access to a better receiver for a test to see if you have the same noise on it?

Computer hash is a known issue.  Turn the computers and the router off for a few minutes and see if the noise goes away.

Finally, changing to a vertical antenna will probably only increase the noise.

Dick  AD4U

[K5DVW]

Interesting... my take.

50KW AM station - not likely to cause a problem at 40m. Or, have you identified that it is? How?
Computer noise - yes, most likely! They're noisy beasts.
Cable TV noise - also not likely.

What you dont want to hear is move your antenna, but what is most likely to work is MOVE YOUR ANTENNA. Sorry! I dont put much faith in being able to filter out noise when the antenna is right above the noise source.

Have you shut off your breakers and run the radio on a battery? What happens then?

Putting an antenna OVER the house is inviting noise from anything in the house that's plugged in, and some stuff that isnt! The further you can get away from that, the better you'll be.

[WX7G]

The FT-817 is easily overloaded and the AM BC station might be doing this. Activate the FT-817 attenuator and check that the noise is attenuated the same as a signal. If so, it is not being overloaded.

To see if the noise is coming from your house operate the FT-817 on the internal batteries. Shut the AC power to house OFF. If the noise goes away it's coming from inside your house.

[W2DI]

Thanks for the info Darrin, Dick and Dave (3Ds)

I have to agree. It would be better to locate the primary source and deal with it. And yes, getting the antenna away from the house is probably the only thing that has a chance of working.

I do have an ICE filter that had a good attenuation below 2 MHz ( I don't go on 160 ) and really does a good job on the station with other radios I've had. So I will give that a try and also see what happens when I 'throw the switch! I know a lot of QRM from the several other occupants!!.

Thanks, I'll report back.

[G8JNJ]

Hi Joe,

I can operate on most bands with my attic antenna only 10ft above the shack PC and all its associated noise makers.

First I'd try adding a good 1:1 balun on your coax at the point it transitions into ladder line, then I'd add another near where the coax enters your house.

The next stage is to eliminate as many of the noise sources as possible, beware you will need a lot of ferrite to do this effectively.

See all the usual web references.

http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf

http://audiosystemsgroup.com/RFI-Ham.pdf

http://www.karinya.net/g3txq/chokes/


Some of what I have done is shown here.

http://g8jnj.webs.com/EMC%20and%20Amateur%20radio.pdf

Hope this helps.

Regards,

Martin - G8JNJ

www.g8jnj.webs.com

[WA3SKN]

You are in an excellent position to find this with the FT817... it can be battery operated!
First, kill the main breaker to the house... do you still have the noise?
Assuming not, then bring up the breakers one at a time.  Any that increases the noise level should be noted, and the eqpt running off that feed.  By doing one breaker at a time you will be able to note multiple sources and their levels of interference.
Then you can determine whether distance (noise source to your antenna), shielding (between noise source and antenna), or filtering will be the best solution(s).
If the noise is still there when you kill the main breaker, you can use a small "sense" antenna and that portable radio to try and locate the source(s) in the neighbors' houses.
Good luck with the project!
73s.

-Mike.

[WA4053SWL]

Hi,
My personal experience.
I here had terrible noise, I live in an apartment complex, surrounded by noise, in my house there are four PC with routers, cable TV, lights on the front that also generate noise , etc, etc, in all my HF receivers JRC-525, Icom R71 and FRG-7700, even with Time Wave DSP-9, in 75 meters listening constant noise of S-8,9,9+, in 31 meters broadcasting band, 41 meters HAM band and broadcasting band was impossible to hear anything below S-9 , so I decided to buy new one MFJ-1025 with minimal positive results , look for a one JPS ANC-4 on ebay and wonder!! , in my case (noise level), the noise of 75 meters remain in S-2, 41 meters HAM and broadcasting band completely remove the noise , and makes an excellent job in the other HF frequencies , note that the MFJ-784 (also have one but is better TimeWave) is one thing, and another thing noise eliminator, good luck, hope solve the terrible problem for our hobby.
73 george

[KK7KZ]

I live in a very similar situation, two BC stations within 2 miles causing interference and a multitude of electric fences in the neighborhood.

Best solution so far: ICE filter (the 80m version, not the 160) and a DX Engineering 1:1 balun on the dipole. Noise is now S2-S3.

I'll be watching this thread for other suggestions.

-R.

[W2DI]

Thanks very much also to Martin, Mike, George and Ron!

All good info. I have some detective work to do and some things to try.

I do have the same ICE filter as you do, Ron, and have to try that for the BC station. They are fantastic...don't know why I haven't tried that first.

Good point Mike. A good plan makes it easier. And the Balun idea is another thing I can try, Martin.

George, the ANC-4 is a wonderful device and for any single source noise cannot be beat! I used one mobile once to completely remove the horrible noise coming from, of all things, a fuel pump, which was located INSIDE the gas tank!

I guess all these things are getting us back for the TVI we caused (but mostly weren't at fault for) in the pre-cable days!

Thanks again all.

joe -- w2di

[AF4O]

Is it affected by rain/weather? Do you have power poles about or are the power lines underground? If its affected by rain, then consider it maybe power line arcing. A tiny unseen power line arc can cause big time wideband noise. Ive had substantial experience in this area.

I am in doubt of BC interference a mile away. Ive had the 817 in many locations and have not experienced any known BC interference.

Computer hash is more likely but around here computer RFI seems to be more on the order of harmonics on specific frequencies and not wide band noise. Ive had as many as 5 computers going here and not a serious wideband problem. Maybe ive been lucky. Harmonics can be annoying though, always on the frequency i want to work it seems :-)

Cable TV RFI. Ive never had any except for VHF specific primary/shared and harmonic but again not wideband. Cable lines all around me.

Yes you are correct. Filters can be helpful for a single source but with wideband issues, you need to fix (or have fixed) the generation point.

I have a tolerable RF location now around my house but it use to be awful before having all the arcing power lines fixed. Guess thats one reason now i enjoy field operation at a nice park with the 817 and other radios. Often zero noise level! You will think your receiver is broken!

Chuck
AF4O

[W2DI]

I have a friend about 20 miles from here who has been going around and around with the power co. on the very issue Chuck. He does have much more of a noise level in dry wx.

I don't notice any difference if the wx changes, so it may not be the same problem.

I do find a lot of 2M repeater frequencies around my home have enough noise to open the squelch at all but the tightest settings. Not all, but certain frequencies and always the same ones.

In fact, my group repeater on 146.925 is one that has noise and opens the squelch at nearly any setting. When I get in the car in the morning, the frequency is noisy and instantly quiets when I drive away!

That is the confusing part. On HF, the noise seems rather broadband, while on VHF there is noise that is much more frequency specific!

I'm going to have to do the power down thing and see if anything changes and try some other tests.

Thanks Chuck!

joe

[MM0EEY]

Hi, I can confirm the MFJ-1026 works, I got hold of one to solve a noise problem here and it does work. I used an outdoor vertical as the sense antenna against my Windom as the main antenna.

I don't think anyone has mentioned magnetic loops yet, I have just got hold of one of these and it blitzes the noise right away. You have the joy of a Hi Q antenna which does seem to work reasonably well against the drag of having to retune often as it is very narrow bandwidth.

If the noise is that bad, it is certainly worth trying these devices to save your hobby. At QRP levels you could easily home brew a loop.

Pete

[KD6KWZ]

What kind of shape is you power ground in? On a side note, I was helping a friend to replace a breaker in her houses' electrical box, and notice that some of the wire screw terminals were loose! Things like that could generate noise.

I've heard of some computer power cord with ferrites built into them. You could turn all of them off & the router, then start them one at a time to see the worst offender(s) of them.

What frequency does the wireless router use? I thought they were in the GHz range. But, they could be making interference at other frequencies. You can get shielded CAT-5 cable.

Yes, I could pick up an electric fence a half mile from where I lived, it was broadband HF-SWL interference.

-Mike H.

[WD8KNI]

Get a portable AM transistor radio and go around the house, also check out light and power poles near the house.  When checking out power poles carry a big hammer.  If you near noise near the pole hit it if the noise changes you found it.  Other very bad sources of noise in the house.  Light dimmers, computers, are huge noise generators.   Is the noise worse at night, if so check out the light poles on the street, another real problem.  The one which lights and goes out, then relights are bad..  good luck.. Fred