The AM Forum

Every since I moved (across the street) the noise level seems very high.  I am running the same basic antenna, an inverted V at about 30ft.  The only big difference is that I have to use a coax feedline.  Getting rid of the 1:1 balun at the feed point did not help, nor did switching to the fat coax.

This sure sounds like RFI to me but I cannot match it to any sound files on the web.  Perhaps I am not experienced enough to realize that this is normal band noise, perhaps not.  

I am not able to participate in the NW 3870 net anymore where I could across the street (that was about 7-8 months ago).  Now I am kicking in the r-390a 4khz filter all the time, usually to no avail.

I would appreciate any advice.  Like I said maybe what I am hearing is normal for the antenna, band, season etc., it just really gives me the impression of RFI on top of normal background noise.

Sound file attached.

Rich

Upon further reflection, I realize there is a lot of investigation I could do.  I think a good start would be to kill all the breakers in the house except the receiver.  I am think of all those awful dimmers in the kitchen.....

Rich

You might find it helpful to "sweep" the premises with a small AM transistor radio tuned between stations in the BC band. Unplug AC power from rigs in your shack and unplug the coax too, then sweep indoors and out, especially along your coax run. Repeat with coax and AC in shack connected. Using this method you can often isolate where the noise is entering the system.

Rich,

From your MP-3 sounds like typical AC line noise.  Are the legs of your dipole running parallel to a power line?  Does the noise vary with rain, humidity level, and/or wind?

Snooping with a portable radio with ferrite bar antenna should help you get a handle on the noise source.

That sounds a lot like the crap CFL's spew.  Could be yours, could be your neighbors'.

Possibly defective CFL noise. My house is full of them and not one little peep.
The sound is like a flourescent. The electronic ballast types can do you in and certainly an under-cabinet fixture definitely. Those types with no ballast. The tube could be bad. Or has become an RF generator.
That BUZZ sounds very familiar.

Fred

Years ago, I had a noise problem that seem to be coming from my house. Went down to the breaker box with a portable shortwave radio so I could hear the noise. Shut off each breaker one at a time. Around the fifth breaker shut down, the noise disappeared. Went up to the living quarters to see what all was off with the breaker in the off position. Turned out I had a dimmer for the dining room center ceiling light that was causing all the noise. Made the case to the XYL that dimmers can be "bad" safety hazards. Haven't had a dimmer since.

There are many things in the typical household that seem to make that buzzy type of impulse noise, from light dimmers and poorly surpressed CFL's to the whole assortment of AC wall switching supplies. I just went through a session with my D-Link router's AC switching wall supply, which was spewing all sorts of garbage on 160-40 meters, and finally built a regulated 5 vdc linear supply to power it. That ended the noise once and for all. From your mp3 file, it sounds like more than one thing going on, with one very loud buzz imposing itself on top of everything else.

The attached picture of a small section of your file shows one very distinct impulse and perhaps two other fairly strong ones in between. I can also hear something sputtering now and then as if it cannot sustain an arc. If the noise disappears in wet weather, I would be suspicious of a blown lightning arrestor or ground wire on a pole somewhere in your vicinity.

Rob W1AEX

Well guys I think I found the main culprits, two dimmers in the kitchen handling 12 (!) floods. I also found a few CFLs which are now in the garbage.

The XYL requires the dimmers :-(. Anyone know of less noisy dimmers?

73

Rich

One of those little 100 watt variacs that mount like a potentiometer.

Here's another idea that works for me: in one of our rooms I rigged up a two position dimmer switch: dim and bright.  The wall switch turns the light on and off.  The light fixture had an on/off switch as well, which I thought was a useless redundancy so I wired a 1A diode in parallel with the switch.  In the "on" position the diode is shorted and the light comes on full brilliance.  In the "off" position the diode is in series with the lamps, so they run off rectified a.c., 50% duty cycle, and shine about half brilliance.  You turn the light on with the regular wall switch, and pull the chain on the fixture for dim or bright. That is all the  dimming action I have ever seen any need for.

.01uf 1KV discs from the dimmer in and out to ground might help.

Another thought....

  check that you have good conductivity between all parts of the electrical  'box' and the light dimmer. If you don't have a metal box, maybee replacing with one may be helpfull.  Probably won't help, but, one never knows, do one?

EMT Conduit??


klc

I went out and bought 1000W replacements, perhaps the higher rating will help. 

As I went sniffing around the house I found the noise to be VERY load outside, anywhere near the main box/meter.  Is it normal for the electrical service to sing like this?  I was eyeing the eighty year old ground rod...  Maybe I am getting paranoid.

I also notice that the TV cable (Carrying internet, no TV) really sings (a loud hiss) as well.

Rich

I have found that some of the outdoor flood/spot lights that have a "built in" sensor for on/off, can emit as horrendous an amount of noise, buzz and hash has as any kind of light I have ever tried.  Its worse when the light is off during the day.

73 and good luck
Ted W8IXY

I had all kinds of things causing noise at my house.

The worst was my Philips HD DVD player.. even when OFF.  I had to unplug it.. Caused S8 on 75 meters.

CFLs in Kitchen.. 

Electric Shaver charger.

I used the Small AM Transistor radio and found most of the items.  The big one for me is the pool pump next door. When its running it can be S7 to S9 on some bands. 

One big one for me is that my house had no Ground Rod.  In AZ its not required. The main house Ground is hooked to the metal conduit that runs to the underground line to the power Transformer in the street.  I added an 8 ft rod and this really helped out.  The ground is wet all the time as the sprinklers run right there.

The biggest improvent is when I grounded my Dipole through two Large Coils.  This killed all the static pops and hash. 

Good luck!

Clark



 

say what?    :o  you b funnin, right?

Thanks for the tip, Clark. I found my DVD was pumping out crap as well. Unplugged it. You da man!

Glad I could help!  Its not common for me to add much to the board! (young Am'er)

I have most things unplugged or switched now.  This year, My dad put a 56 solar panels on his house in order to reduce his $900 a month electric bill (Damn California).  It worked.. With the solar power and the fact that he Cut his usage down alot, His bill is about $30 now.

I learned about devices using power even when off.  I went around the house and really trimmed down my power usage and the results where a slightly lower bill and less noise on my Radio :)  win win.

Clark

Years ago a neighbors solar panel switching supply created the worst RFI I have ever heard, bar none. A buzzsaw noise, similar to Cold War shortwave jammer stations with spurs every 12 kc. Yikes.