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Legend
| | Posted on Tuesday, February 25, 2003 - 5:01 am: | 
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Hi...
Since I moved into my new home, I have been experiencing a rather annoying problem. You see, I have aquired my own home, located in a decent area (radiologically speaking), and I have a beautiful set up, radios, antennas, ect... Only, there is an incredibly irritating EMI buzzing that is occurring up and down the CB band on various channels, as well as other parts of the HF spectrum. I have determined that it is DEFINITELY coming from outside of my home, and that it is not very close by. I will have to go hunting the neighborhood to find it. It sounds like a leaky power pole transformer, or capacitor, or whatever. I want to hunt it down, using a RDF (Radio Direction Finder). The ones used on 10/11 meters are generally a small copper loop made of tubing, or thick, single element wire, with a capicitor used for tuning the resonance, all mouted on a sawed-off broomhandle, or piece of PVC tubing.
I'm sure that some of you hams, and CBers are familiar with what I am referring to. I am hoping that one of you might be able to give me specific instructions on how to make one (if so, be specific please) or direct me to a website that has instructions on how to build this 27, or 28 Mhz small loop Direction Finder. Even if I can't use it to track down the EMI problem, I would still like to have one to mess around with.
I have heard of others who have had a very similar EMI (Electro-Magnetic-Interference) problem on their radios, i.e. buzzing noise thoughout the band, on regularly spaced channels. Were you able to track it down? If so, was it a power pole, or what? I'm sure you know how annoying it is to have a base radio (which would normally be nice and quiet) that has 5 S-units worth of buzzing on certain channels, one of which happens to be you home channel. It really sucks!
If anyone can help me with building an 11 meter Direction Finder, I certainly appreciate it. I will be using a portable shortwave receiver with a good signal meter and RF gain, hooked to the Direction Finder, to track down this noise source.
Thanks! |
Crafter
| | Posted on Tuesday, February 25, 2003 - 11:32 am: |
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Any street lights nearby? Mine was a photo cell gone crazy but I went throught the electrical company and there guru and me carried my 20 lb hammer to the poles till we found the one the shuttered when hit. They changed everything on the pole too. I can say I was impressed. |
Viking
| | Posted on Tuesday, February 25, 2003 - 3:12 pm: |
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What I did once was took my Unidem Pro 540e (has an RF gain dial) and a straight approx. 14" coat hanger stuck in the antenna jack. For power I took a plug to fit in the radio and about 12" of wire going to a fresh 9V battery (the kind you stick your tounge on to test). Enough juice to make the radio receive. Taped it to the radio. I was able to actually point the 'antenna' towards the source of the noise. With the RF gain, you can narrow it down even more.
My "problem" turned out to be the neighbors' tv signal booster. What I thought was wierd was that it wasn't the transformer that powered it causing the noise, but that the coax connector to the back of the tv was loose. Simple fix.
Good luck. |
Weakeststation
| | Posted on Tuesday, February 25, 2003 - 3:23 pm: |
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I have a problem over here, i traced it down to computers and the monitor.
I have talked to alot of people, and a few traced it down to this as well..
Some has it, others don't..
take care, im back out
p.s ch.31 is real bad when my monitor is on, radio is in a diffrent room |
Tech833
| | Posted on Tuesday, February 25, 2003 - 6:09 pm: |
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This is one area where the FCC is your friend. Contact your local field office and file a formal complaint. I have DFed many of these cases for the local office and the problems got resolved.
BTW: I use doppler DF. http://www.dopsys.com/ Works on CB just fine.
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DeadlyEyes
| | Posted on Tuesday, February 25, 2003 - 6:58 pm: |
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Re Legend...This may be long so sit down
The first thing to do is to eliminate your home as the cause of the noise. Cut off every circut breaker (including the master breaker(s)) and listen on the Mobile CB. Does the noise stop? If it does then the noise is in YOUR home wiring somewhere. Click on the breakers one at a time working backwards from the power pole to your home so as to isolate the part of the house/room the noise is located. Then go into that room and disconnect everything and I mean everything then one by one reconnect and turn on each ting one by one. Touch on/off lamps are NOTORIOUS for making annoying noises. Unplug and check those first if you have any. Find the noise and eliminate it. Also check out the doorbell transformer. Those bad boys have thermal fuses that sometimes arc and all kinds of commotion.
Once you have eliminated your own home as the reason for the noise it is time to break out the AM/FM transistor radio. Use the FM band and tune to where there is no radio station. When you get close to the cause of the noise you will hear it on your little FM radio. Hope it is NOT in another persons home. If it is you may have to be very diplomatic to get them to let you fix it.
Now if you find where the problem is in an electric pole you still could be in trouble getting the repairs. Some companies refuse to repair the problem unless forced to by the FCC. Some utility companies have little respect for amateur complaints and even less for CB complaints. Dont hold your breath because the FCC will probably ask you to jump thru all the legal hoops before they act. Amateurs have had to wait over a year before their noise problem was fixed-notify, wait, notify wait, evade repairs, wait, FCC threaten, wait, and at last repair (with luck).
The best case possible is if the problem is in your own home believe it or not. That way you are in control of the measures you take to solve the problem. |
Kraig
| | Posted on Wednesday, February 26, 2003 - 6:59 am: |
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Try contacting the local power company using their service department number. Tell them you are getting EMI. If the interference changes with weather conditions (wind/rain), then it most likely is coming from loose or dirty insulator connections on their high voltage electrical system.
If they can't find or fix the problem, then contact the FCC. |
Czar
| | Posted on Wednesday, February 26, 2003 - 5:30 pm: |
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Hey Legend just one thing,before calling the FCC about this problem and then the possability of "someone" showing up at your door.Make sure you get rid of ALL your equipment except for an unmodified 23 or 40 channel radio sitting on a bare desk.Otherwise you might wish the interfierence was still there and not uncle charley ! |
Legend
| | Posted on Wednesday, February 26, 2003 - 8:24 pm: |
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Thanks for all your responses. I'm sorry, I should have been a bit more complete in my explanation. I have already taken just about all the measures mentioned above. I have already determined that the noise is NOT coming from within my own home. And the noise is DEFINITELY coming from over the air, and not through the power coming into the house. I have shut down all of the power breakers, and run the CB from a battery, and STILL get the EXACT same noise. I have taken portable radios (AM/FM, scanner, shortwave, CB, ect...) all around my property, and I get the same strength of interference anywhere on my property.
The EMI is definitely coming from somewhere else in the neighborhood. I do not live in an industrial area, and it is a fairly small town. Just power poles, street lamps, and other homes, up and down the street. I figure if I can make a decent direction finder, I can track down the source of the aggravation. I figure if I can "hand deliver" the right power pole or street lamp to the power company, they will be much more likely to help me STOP this interference, by repairing the problem. If it turns out to be a neighbor, then "extreme diplomacy" will indeed be the order of the day. But until I find out which, there is NOTHING I can do about it.
So, if anyone can give me (or direct me to) the plans on how to construct a small RDF loop for 10/11 meters, I will hunt down the problem, and report back here with my results, and a description of what was causing the problem. I am very good with constructing things if I have the proper instructions (dimensions, values, ect...), so if anyone knows how to make one of those simple CB tracker loops, please let me know. A friend of mine (from years ago) used to make them all the time. They are made from thin copper tubing, a stick, coax, and a capicitor to tune the resonance properly. Do any of you now what I am talking about? If so, help me out here please.
Thanks guys. |
exgi
| | Posted on Wednesday, February 26, 2003 - 10:50 pm: |
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UFO's |
707
| | Posted on Thursday, February 27, 2003 - 2:01 am: |
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can you record the noise and post it somewhere or mail it so we can hear? |
707
| | Posted on Thursday, February 27, 2003 - 2:07 am: |
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you should look here
good loop diagram
lots of RDF info
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Legend
| | Posted on Thursday, February 27, 2003 - 6:02 am: |
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I thank you 707. I have already seen that loop website, and unfortunately, I don't speak Spanish, so I can't tell what the instructions say.
Translator?
LOL |
bruce
| | Posted on Thursday, February 27, 2003 - 7:29 am: |
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i found with loops its a good idea to run the output to a preamp mounted at the feed point it isolates the loop from the coax feed |
707
| | Posted on Thursday, February 27, 2003 - 5:22 pm: |
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707
| | Posted on Thursday, February 27, 2003 - 5:33 pm: |
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And here's the translation from Portuguese to English..
This aerial allows the localization as of check marks by the blank than it is to she provides at the direction from the emission the one detect. As a matter of fact , the one blank generated indicates the one diretion from the emission. Hereby , it needs - in case that as of two lines about to in case that of the dot. This means that along a certain coordination amidst two seasons than it is to have these loops installed AND calibrated ( plant well into chart ) can - in case that in question as of seconds access the position by one transmitter.
THE ONE calibrates is over-simple : tune - in case that the receiver well into 28MHz AND adjusts - in case that the one trimmer for its greater token payment or clatter received. Locations can be located along this aerial by the blank generated. This one he will be indicating the one direction ( I use this aerial aged one receiver SONY ICF7600 AND along this one setup already I found a processor adjacent at the my he marries than it is to insist well into " to pass on to unlicensed "). THE ONE ideal about to RDF is the departure as of object metallic. Can - in case that , in the mean time , to use this aerial at the hood by one car. About to assure the accuracy in the case of a " hunt ", can - in case that to use a season acquaintance AND as soon align The same By this font as of check marks. Along three of these aerials strategically he installs does have - in case that a system as of radiomonitoragem pretty all-'round , helpful well into big ones centrepieces urban where the invasion from the strip as of 10m By clandestine is administering the one to speak. Sadly she is direcional merely about to check marks sites. Those received By reflection ionospheric they are complicated as of he shall be tracking. Anyway , is that the dividend. We may go caretaker By our bandages.
note: those online translators don't do a very good job of interpreting meaning, so I would say that the picture is pretty self explanatory and should need no further instructions. |
Mr_Rf
| | Posted on Thursday, February 27, 2003 - 10:31 pm: |
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Trying to RDF power line sourced EMI is not easy. The best way to track down the noise if with a receiver (am radio, cb, whatever) and centrally locate the strongest area it seems to be in. Then use a sledge hammar and moderately tap the power poles one-by-one and listen for changes in the noise you hear. Ususally the source of power line noises can be "modulated" by vibration!!! Try to talk the power company into letting you help a lineman do this on one of their slower days. If you approch them with a knowledgeable plan then they will be more likely to play along.
I learned how to do this from an American Electric Power EMI guru when I was in the radio field service business.
Good Luck!
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Tech833
| | Posted on Friday, February 28, 2003 - 10:30 am: |
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The only problem is- touching a power pole (let alone hitting one with a sledge hammer) is a serious crime and will likely land you in big trouble judging today's climate.
Also, I am sorry to have to tell you, a loop is not the way to DF power line noise. Sadly, you will find that the loop is only sensitive to the magnetic field (that's how loops work) and you are going to be saturated my magnetic field near power lines with no particular direction.
You need a 'loopstick' antenna. Translation- wire coiled around a ferrite bar. That is the only way (without Doppler or a portable yagi) you will be able to DF noise created by power lines and equipment on your CB frequencies.
I have done this many times myself. I still suggest you contact the FCC and let them DF it with their mobile gear. They do it all the time also. |
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