Line noise and ignition noise

[k4kyv]

Well, like clockwork, as happens every year just about the time the summer QRN finally dwindles away, the line noise is back...   It first started Sunday night, and completely wipes out large segments of the spectrum from the broadcast band up past 7300.  Interestingly, there are a few nulls in the noise, but mostly where I ever hear any AM activity; last night 3610 was almost noise free, while 3850-3950 remains completely unusable, and it's worse on the beverage than it is on the dipole. 

I tried driving round the area, using a portable shortwave radio and a RadioShack VHF AM aircraft receiver,  but have not been able to localise the noise.  One problem is that both cars generate so much ignition noise that it masks any good peaks and nulls in the noise.  The car radio doesn't seem to pick it up on the AM band, but the coax feeding the radio is buried so deeply behind the dash that I  would have to tear the car half apart to gain access to the line to feed it directly to the portable radio. Maybe a simple whip antenna mounted on top of the car would be better shielded than listening with the built in whip antenna on the radio, from the interior of the car. I used to have an old whip antenna with mag mount, but can't find it.  If they still sell cheap CB antennas anywhere, maybe I'll pick up one and  gut the insides and use it as a simple whip. Or I may try using a bicycle.

It's damned if you  do, and damned if you don't.  If it's not one thing it's fifteen.  Sometimes I wonder if it's worth all the hassle.  That could partially explain the lack of activity on the amateur bands of late. 

[WQ9E]

Don,

If you can lay your hands on one of the older direction finding receivers aimed towards boaters the antennas on these tend to produce very sharp nulls and you should be able to stop your car at a few places with ignition off and triangulate a position before setting out on foot to really narrow it down to a specific pole or small area.  I have an old Raytheon BCB/LW/MB boating receiver and the combination of a clean null from the bar antenna a the use of its "sense" antenna make pinpointing noise much easier than using most portables.

The worst noise I find this time of year is from those damned PTC space heaters; they put an incredible amount of hash on the line and it makes my normally very quiet rural area noisy.  I located one 2 years ago that was creating S9 + 20 noise on my Drake R-7 and it was almost 3 miles away.  The owner wondered why all of his radio and TV equipment suddenly had issues and gladly got rid of the piece of C__P.

Rodger WQ9E

[WA1GFZ]

Don ever measure AC current on the feed line shield? Maybe you have a big ground loop.

[KM1H]

I assume you have killed the main breaker in the house and listened on a battery RX? Maybe asked neighbors to do the same?

The DF radio is a good idea, I use an early 80's SS Ray Jefferson unit, but realize the DF antenna is usually only switched in for LF and BCB.

The 2 and 6M yagis at home give me a bearing and in the car I use an obsolete model Wavetek CATV VHF/UHF cable sniffer I snagged for about $10 at a hamfest. Its AM, tuneable and has a speaker. The DF radio in the car gets me in the area as well as reverse bearings to the house along with a compass; the VHF gets to the pole or house/building.

Its almost always an adventure.

Carl
KM1H

[k4kyv]

It's nothing in the house or nearby.  I can hear it a half mile away, but so far haven't been able to pinpoint anything.  The power lines can carry the noise for miles.  That's why the AM broadcast band usually isn't very useful for tracking down noise.  The higher you go in frequency, the more localised it appears in your receiver.

Naturally, the noise is intermittent, so you end up spending a lot of time just waiting for it to show up.  As soon as I set out to chase it down, that's when the noise decides to take a break.  But I can always evoke it once again by returning home and getting on the air.

[w4bfs]

Hi Don ... be sure to carry a 4 lb hammer with you while noise locating, especially for intermittents ... when you come to the PUT (pole under test) give it a wack wit the hammer ...may or may not help you help you find the noise but you WILL feel better ...73 ...John

[Roy K8VWX]

            The sledgehammer is a must if you get it down close to a pole or two Don. The power company here in Columbiana frowns on using one but I talked them into using it for an intermittent problem I had. I tracked it down to a lightning arrestor about 3/4 mile away and when they came out to check it - NO NOISE.One good rap with the sledge and WOW. The fix - Get rid of the lightning arrestor. They said it was not necessary anyway. 73/Roy (See you on 160 later Don)

[k4kyv]

Sometimes you can take a gentler approach and simply yank on the guy wire if the pole has one.  A massive rubber mallet bought just for the purpose might be more appropriate (I have seen those in automotive tire and body shops so they shouldn't be too hard to find).  You don't want some butt-hole in power company to retaliate for the inconvenience you have been causing them, with a bogus claim that you did permanent damage to their pole and a demand for monetary damages.

[KE2EE]

Don, Why not turn this RFI problem over to your local power company? I say this because I work for a power company in the NE doing communications work and one of our jobs is investigating RFI/TVI's. We use a commercial made 300 mhz rx with yagi ant. to locate the noise to a pole.  Then a ultrasonic dish with amplifier to listen to arcing hardware on a pole. Yes, first we shut the customers main breaker off to see if the problem is in the house. About 50% of the problems ARE in the house. If not we search a 3- 5 block area looking for a bad pole. Then we turn the work over to the line dept. Sometimes we need to return if there are multiple noise sources. I try to work closely with the customer until the noise is gone and their happy. Give it a try.
Mike

[k4kyv]

That would be a joke.  The local power co. will fix the problem right away if I find it for them, and contact the guys who actually do the work.  I contact them by calling the night-time emergency outage number and talking to the night crew.  Reporting via the regular daytime outage number doesn't work.  All I get is an interminable voice mail menu, and when I leave a message nothing ever happens.  If I just report that I have radio noise, they don't have a clue.

This same power company made national news a couple of years ago when the FCC got onto their case regarding non-resolution of another case of line noise and an amateur station in another town.

[k4kyv]

I usually tell them it is interfering with my AM broadcast radio.  Most people in this area have cable or satellite, so the power company is about as unsympathetic to the "cheap bastards with rabbit ears and rooftop TV antennas" as they are to hams.

The noise was back full blast tonight.  S8 on the beverage on 75, and only the strongest stations ever exceed S9 when I use this antenna.  The TX dipole is quieter, and so is the beverage on 160.  I drove round some more this evening but have not been able to pinpoint anything.  It seems to be somewhere in this area, but even listening on 10m the hash appears over a broad area and doesn't get louder at any particular spot.  Can't pick it up on the VHF AM aircraft receiver. I put the portable radio on the dash, stick the whip antenna out the window and let up the window onto the whip, and the glass holds the radio in place and the car body seems to shield most of the ignition noise from the whip.

They snuck in a power substation about a quarter mile from here, just before I moved here in 1979.  Nobody in the local area knew anything about it until they had started construction work. There must be a dozen phases going out from that p.o.s., with a set of poles on both sides of the road in all directions going away from the station. Each pole has two sets of crossarms and each one of those carries 3 HV wires, plus a common neutral below the crossarms.  With that many lines, at any given time odds are good that there will be a problem on at least one.

What sucks is that after more than 100 years of power distribution, it is mostly 1910-era technology that is still used throughout the industry.  You would think that by now power distribution technology would have improved to the point that arcing insulators and loose connections would be ancient history.  These things are also known as power leaks, and cost the power company money, just like a pin hole or a leaky pipe connection in a natural gas line costs the gas company money. When I drive into town, noise from the power lines running along the side of the road is so bad that it's often hard to hear anything on the AM band on the car radio.

[ab3al]

Don have you seen any black helicopters flying overhead lately???


just kidding dont worry about smacking the pole with a 3 pound linemans hammer.  thats actually a bellcore requirement before climbing a pole.  We strike it many times sounding for rot.  Had the same problem here for a while and it turned out to be a battery operated pizzo ignighter on a gas grill 1500 ft away on the porch of a forclosed home.

[k4kyv]

The power company here will foam at the mouth even if you attach a yard sale sign to one of their poles with tape. 

But if they ever made an issue about banging on their poles, I'd tell them that if they would fix their damned power leaks I wouldn't have to be banging on the poles. 

They claim that signs are prohibited because people use nails and staples in the wood, and that it can injure the linemen when they climb.  With a heavy 10 lb, steel sledge they would probably say I was making splinters in the wood that could cause injury.  The ridiculous thing is, linemen haven't climbed a pole round here in 20 years.  They use a cherry picker truck for all their line maintenance now.

That 10 lb sledge probably would raise some splinters.

[k4kyv]

Ahhh yes..., Tesla technology still in use today. I could be wrong, but there may not be much more they can do with it. You need lightning arrestors on above ground power lines and there will always be connections that come loose. Underground power lines are the better way of doing it today.

I'm sure with a little R&D they could come up with a lightning arrestor and a pole insulator that would not be prone to breakdown, and a clamp could be developed that would not come loose.

One of the greatest problems is that they switched from copper to aluminium wire a  few decades ago.  It is notoriously difficult to keep a tight connection to that stuff.  The metal tends to flow away from the pressure spot on the clamp.  That is why aluminium house wiring is such a fire hazard that it is prohibited by most local electrical codes.  A chemist once explained the reason, that the molecular structure of aluminium makes it not really a solid metal, but something more like an extremely viscous liquid.

The problem would be solved if they abandoned mechanical clamps altogether, and went to something like  cad-welding or brazing to fuse the wires together.  It would save the power company a lot of money if they didn't have to constantly have crews out fixing those failures, which cause more serious problems than just line noise. 

[KM1H]

Its been over 25 years since a lineman used climbing spikes around here and one gave me his pair.

I suspect OSHA had a lot to do with it.

Carl
KM1H

[Jeff W9GY]

Don, we use a 3 element yagi tuned to the aircraft band and a cheap Radio Shack handheld with aircraft band capability.  Since aircraft radio is AM, it responds nicely to pulse noises.  I can usually get to the pole in question...luckily I have the cel phone number of my local lineman, and he's been very helpful in fixing things...of course, we bribe him a bit with a free lunch etc.  HI

[k4kyv]

I have the Radio Shack aircraft handheld receiver, but just use the whip antenna and move around to find maximum signal strength.  Wouldn't a full size yagi at that frequency be a bit cumbersome?

And how do you  feed the output from the yagi into the radio?  Mine just has the extendible whip and no external antenna input jack.

Unusual in that I can hear this case of noise at 30 mHz, but nothing in the aircraft band.  It's worse on 75 than it is on 160, and worse on the beverage than on the xmit dipole.

And naturally, like 99.9% of my radio problems, it's intermittent.

[W2PHL]

Don, Maybe what your hearing isn't line noise at all. Your symptoms all seem to fit RFI generated from a plasma TV. The fact that you do not hear it in the AM broadcast band is a big clue. Most of the hash they generate is higher in frequency. I know first hand how bad these things are. I bought a plasma TV for the family last year. The buzz it puts out sounds a lot like electrical noise. It has peaks and nulls up to 30MHz. I put doughnut toroids on all the TV's cables and was able to reduce the buzzing from 60db to 40db (R-390/A carrier meter). Still bad but much improved. There are apparently other plasma owners in the neighborhood as I can here their TVs as well.
If you have a neighbor with a plasma TV place your shortwave receiver in front of it and watch (hear) what happens! It's amazing that the FCC allows these things to be sold. FYI
-Phil

[k4kyv]

A half mile away, with no nearby power lines to carry the signal?  I can hear the noise on my portable radio out in the middle of the field.  It comes and goes, just like line noise.

I suppose the plasma TV's can get away with it the same way the touch switches do.

[W2PHL]

A half mile is a distance. The garbage they put out however, can be quite strong. I don't mean to send you on a goose chase but check out this link.
http://www.dxengineering.com/TechArticles.asp?ID=%7B1D9AAC83-E591-46D4-86AE-B84F1CBF1D62%7D

[k4kyv]

The security company, ADT, talked with Panasonic, who informed them that there was nothing that could be done. I owned it.

I'd bet that owner could raise holy hell with the local dealer and get his money back. There is usually a warranty period on electronics, and most local dealers will accept returns on equipment that doesn't work satisfactorily, for whatever reason. Maybe if enough people returned those things and complained that they interfered with their radio, the manufacturers would do something.  I wonder if the QRM wipes out the AM broadcast band as well as short wave.

[W2PHL]

The RFI from a plasma isn't that bad in the broadcast band as opposed to RFI from electrical arcing.
        Fortunately plasma technology is on the way out. LCDs are becoming the norm. I bought my plasma because of its superior viewing angles and contrast levels not its radio jamming capablilities! The common mode chokes I put on all the in and out cables keeps the noise from radiating through the wiring but it doesn't come close to eliminating it. 

[ab3al]

no you can still climb a pole.  the nails were a big deal primarily because if you spike one it would darn near ruin the gaff.  Osha got on their case because by definition the climbing belt is a body positioning belt and not a safety belt.  the answer was a second strap that wraps around the pole in the opposite direction forming a complete loop around the pole. now if you cut out you only fall about 1 ft.  even though im out of it the neighbor works for the power co and let me try his.  Really puts you at ease.

[Ralph W3GL]

Yeah, Mike...

Borrow his belt some weekend and do my poles...

[ab3al]

wondered how long it would take ralph.  I have a 60 ft cherry picker at my truck lot for sale.  its on a tri-axle with airbrakes. trying to get my brother to take a ride with me.  I dont have a cdl