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Author Topic: Extremelly loud Static Noise from AC lines.  (Read 5030 times)

Posts: 9

« on: August 27, 2002, 10:11:58 AM »

Hellllppppp  Just recently I started to hear an S9 noise level at it's highest range in the 14 mhz area.  It tapers off in both directions.  So - I can no longer operate on 20 meters (CW)/.

I use an 817 QRP and a stealth long wire as I live in a condo.

I traced this new noise to my AC lines, and assume it comes from Con Edison..

What can I do about this??

Thanks,   Peter K2MMT

Posts: 21764

« Reply #1 on: August 28, 2002, 09:25:15 AM »

How did you trace it to the AC lines?  I doubt the noise is coming from Con Edison; but if the noise is indeed being carried by the AC lines, it may be conducted via those lines from any number of sources, probably one very locally to you.

-Try using a portable AM radio to sniff the AC lines and find the source.  Of course, you may never really find the source this way, but it might help you find something helpful -- possibly even something you can report to Con Edison.

-Assume you've operated the FT-817 on battery power (since it can do, anyway!), and completely shutting OFF everything in your home by switching the MAIN circuit breaker OFF.  Once everything in your home is completely inoperative except for battery powered stuff, see if the noise is different.  If the noise goes away when you do this, YOU (something inside your home) are the source of the noise, and the AC line is simply carrying that noise around your home.

I've found most band-specific and frequency-specific noises (like, it peaks around 14.200, and drops down a bit above and below there when I tune around) are man-made, and not caused by the utility company, but rather by appliances connected to the power lines.  I've traced bad noise sources down to:

-TV sets
-DVD players
-Lamp dimmers
-Electric (digital) clocks
-Digital timers operating alarm and sprinkler systems
-Cable TV converters
-DSS (Direct TV or Dish Networks) converters
-Low voltage halogen lights
-Fluoroescent light ballasts
-Loose electrical connections, including at appliances and service panels
-Loose electrical ground connections, at service panels or ground rods
-You name it!

In most cases, the cause is not the power company, but rather stuff we all connect to the power lines.  Usually, if the noise source is local, you can find it, but in a shared living environment like apartments and condos, this can require cooperation from neighbors, since the noise may be originated in one of their homes.


Posts: 9

« Reply #2 on: August 28, 2002, 05:30:56 PM »

Thanks - but I did completely shut down the main breaker, therefore discnnecting the entire house from the outside.  The battery operated 817 still heard the noise.  I walked around the immediate neighborhood with it, and placed it by the nearest power XFMR.  But I did not hear any noise outside of my house.  Odd!!  This weeekend I will go into it further.  Possibly there is something nearby that is being radiated by my AC lines in the house - like a big antenna.  

When I walked around the house, before I turned off the power, I placed the antenna next to appliences, and wall outlets.  It went crazy everywhere it was near the AC - even the Telephone lines....  When I moved it next to the TV screen (TV off) it was the loudest.  

Frustrating, but somehow we will find the culprit - I hope!!

Tnx  73  Peter  K2MMT

Posts: 729


« Reply #3 on: August 29, 2002, 05:08:41 PM »

As I understand it, you did not hear the noise when you took the radio outside your house.  But you still heard the noise 'inside' your house even after turning the power to the house off.   That is truly odd.

What it suggests is something is not controlled by the master breaker and remained on.  If you are in  a rural area you may have a well pump, or a security system, or a mercury vapor yard light.  You may also have something coming into the house on your telephone lines.  If there is a junction box outside the home for the phone lines, monitor the radio while unplugging the phone lines from the junction box.  

If you have an alarm system, including one in your garage, turn it off.   If you have mercury vapor lights outside, unscrew the bulbs if possible.   Better still, if they can be turned off, then do so.  

Think back to when the noise started and how it started.   What changed in your home about that time?
What changed in the neighborhood?  Did you see other problems, like phone line static, or computer changes in connecting online?

Is the noise constant all day long, and all night?  How about on weekends?  Is it worse during a rain, or better?  Or no change?  How does wind affect it?  

If my initial presumption is correct, that even with the power off, the noise is still present AND it can only be heard inside your house, then there is only one possibility - some wiring is bringing noise into the house and that wiring is not controlled by the circuit breaker.   When you turn the breaker off, is this the one inside the house?  Is there another breaker located on a pole outside?  If so, turn the power off there as well.   Most houses don't have that capability, but many rural ones do have breaker boxes on a pole outside, as well as the ones inside.  

I had a strange noise a couple of months ago, across most of the HF spectrum, and very strong.  Using a portable AM radio I went outside and -- no noise, or very weak!   I came back into the house and, like you, I checked at each outlet.  Any time I got really close to an AC line the noise became very strong.  I switched on the TV and saw strong horizontal lines on the screen (Do YOU??)  

I went to my breaker box and turned off breakers one at a time, until the noise disappeared.  Ah ha!  It was my clothes dryer.   There was a loose contact on the timer switch.  When I turned the breaker back on, the noise reappeared on the TV screen and on my AM radio.  I tapped on the dryer control panel and the noise disappeared.  Source, found.  I took the panel loose and tighted the connections and no futher problem.

Finding noise is a matter of elimination.  Keep at it!



Posts: 149

« Reply #4 on: September 01, 2002, 10:02:34 AM »

I agree with the comments from WB2WIK
I'd like to add....
do you have any energy efficient new style light bulbs?
they generate tremendous noise! remove them and install 60 or 75 watt incandscent bulbs.
the tv noise is due to their cheap switching power supplies and remember they are always on [instant on feature] so when testing unplug the tv's and cable box etc. actually unplugging stuff is the only true way to troubleshoot. I had a maganavox tv 27" that was awful, I was able to exchange it while new for one from a different lot number and that made a difference.
If you feel comfortable and safe...go to your breaker box and ensure all wires to the neutral, ground and breakers are tights! they do loosen over time

your local power company should have a tech support rep. he is a guy [hopefully] who you can talk techy to and he could come out with their power leakeage/noise sniffer to verify if the noise is in your home or out on the pole. be nice they really can help but are reluctant to participate.
any light dimmer older than say ten years go ahead and replace.period. also find the source of the trouble don't buy ac filters that could only be a band aid and the problem will resurface.

just turning off breakers sometimes will not provide an easy answer because there could be loops in the neutral....

well, you have lots of advice from many but here is one last idea...
try the timewave ANC-4 avoid the mfj unit it will not work well. The timewave ANC-4 does help and may cut the noise one or two S-units if not more. It takes some fiddeling with the knobs but it can help.

most likely you have 4 homes on a transformer, it is possible that a neighbor has something  defective
and you're getting it, again the power company troubleshooter should be able to verify that.

good luck and be sure to post your findings so others may benefit from your solution.

regards, Marty  


Posts: 1000

« Reply #5 on: September 05, 2002, 12:12:20 AM »

                   Although often blamed for interference, AC transformers are rarely the cause. The most likey culprit on an
                   AC line is a cracked "bell" which is the bell shaped insulator on the lines at the pole. The cracks fill with
                   dust, moisture or carbon deposits and provide a noisy path to ground. The next most likely cause is a loose
                   clamp on a highline. These clamps have loops that can be hooked by a fibre glass pole from the ground so
                   they can be tightened without the necessity of climbing the pole. They are used to secure the power take-off
                   for a service transformer to the highline...maybe that's why transformers often get blamed for interference.
                   These clamps are sometimes called "Fargos" by old-time linemen after a company that manufactured them.
                   I have seen these things shower sparks to the ground when loosened by the wind. They can wipe out entire
                   neighborhoods with interference. Some power companies are very helpful about tracking down interference.
                   A lot of their attitude is directly related to YOUR attitude when you contact them. Be friendly and ASK for
                   their help, rather than demand it. I spent an entire afternoon riding around with a lineman in his service truck
                   while he climbed poles and checked suspicious bells and clamps for me. An old-timers trick is to whack
                   suspect poles with a sledge hammer to see if the vibrations affect the interference, but power companies
                   take a dim view of this diagnostic procedure! They don't appreciate your beating on their equipment with a
                   big hammer. A less intrusive method of checking is to find a nearby pole with a guy wire and pluck it like a
                   guitar string. The induced vibration in the wires will change the interference pattern on your receiver if you
                   are near the source.

Posts: 21


« Reply #6 on: September 06, 2002, 11:23:28 PM »

All of the above suggestions are good.  I'll add my own observations as I own an FT-817 and also a Small Wonder Labs SW-20+ 20M QRP rig.

I've run the SW-20+ at my office for about a year with no problem, logging over one-hundred 20M CW QSOs using one watt into coax-fed dipole at 35 feet.

I recently bought an FT-817 and brought it to my office to replace the mono-band SW-20+.  To my dismay the FT-817 was beseiged with S9+ noise and birdies every 7-8khz.  Switching the dipole back to the SW-20+ and all such noises disappeared.

I concluded that the FT-817 was somehow more suceptible to man-made noise than my SW-20+.   Incidentally, I was only able to log 1 or 2 QSOs with the 817.. as soon as I switched back to the SW-20+ I could make contacts again.


Posts: 14496

« Reply #7 on: September 11, 2002, 03:15:31 PM »

The only thing in your house that should be still operating with the main breaker off is the meter. I guess there could be some kind of a problem with it.

It is possible that if the noise is generated by a bad insulator on a pole somewhere that the noise (being RF) is still coupled across the capacitance of the open breaker into the house wiring. It is also possible that the noise is conducted by the power wiring for some distance. I once found the defective insulator on a pole almost a mile away. You may find that the noise is really coming into the house from outside but outside you can't get close enough to the wiring to pick it up as strong. Try placing the radio antenna near the meter outside (with the main breaker off) and near the ground wire runing down the power poles in the area. Walk down the pole line to see if it gets stronger in one direction. You may be able to find one pole that is very strong and likely the culprit.

One common curlpit inside the house (although it will go away with the main breaker off) is the door bell transformer. These things have internal over-temperature breakers that can go bad and cause noise.

Bob  AA4PB
Garrisonville, VA

Posts: 4

« Reply #8 on: September 18, 2002, 09:48:09 PM »

 I have a similar problem, loud ac buzz
at 3.680 . Sometimes so loud cannot hear
the cw net I check into. I then bought
a timewave anc-4 noise canceller
 I put up an external 10 ft antenna
that is low to the ground but picks up the
buzz. I then use the timewave anc-4 to cancel it
out. I am able to completely cancel out the noise
so I can hear the cw signals.
 Its abit spendy at $200, but I am glad I have it
 Steve K0KOC
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