The Pig is dead!

Getting up to the 500,000th harmonic is impressive.

Cheers

Phil Hobbs

Spark discharges produce pretty impressive spikes.

Once the voltage is high enough to start an avalanche, the current rises ve ry rapidly. The glow to arc transition that follows isn't anything like as quick - you have to heat up the electron emitting surface enough to let it deform into lots of sharp-pointed field emitters - but the change in voltag e drop at the emitting surface is only about 100V so it doesn't signify.

se the entire time. I had two power outages, Wednesday night and Thursday m orning.

om when the subdivision was fist laid out in 1964. My home was the first on e here. The old had PCB oil in it, so they carefully lowered it to eye leve l. A very thick plastic bag, and a thick adsorbent pad was pulled up over i t, and another pad was laid in the bed of their bucket truck before it was swung over and down into position.

ars ago but 55 years of service in a high lightning area is pretty good.

ithout a lot of 60Hz hash. It used to wipe out everything from 500KHz to 30 MHz. It's amazing that a damaged transformer lasted so long. I wonder what the inside of the can looked like?

io every five or less minutes, and apparently it was affecting my cable mod em and router. My typical download speed was around 17Mb/s I downloaded ove r a GB of files at around 38 Mb/s a few hours ago. I was streaming a TV sta tion and listening to the Internet radio at the same time with no dropouts.

Ham operators talk about problems with this sort of noise being very common . Sometimes it sucks to be a ham.

I wonder if the HF noise is like Bill said, from discharge ? I have heard that pole transformers have caused wideband noise but I almost didn't believe it.

I am surprised that if there are arcs that more trouble doesn't happen.

Did you test the AM receiver in Wednesday or Thursday, i.e. during a larger blackout or when your local pig failed ?

With a huge number of pigs all over the place, a very dense NV (medium voltage 14 kV ?) network is required to feed them. If the MV network is open wire, there are also a huge number of insulators. Dirty or faulty insulators are known to produce a lot of RF noise and also consume some mains power. If you can pinpoint an exact faulty insulator, this might also interest the power company and they will replace the insulator, before it fails completely.

It is unlikely that the pig itself generates RF, but of course if the primary side insulator is faulty...

ise the entire time. I had two power outages, Wednesday night and Thursday morning.

rom when the subdivision was fist laid out in 1964. My home was the first o ne here. The old had PCB oil in it, so they carefully lowered it to eye lev el. A very thick plastic bag, and a thick adsorbent pad was pulled up over it, and another pad was laid in the bed of their bucket truck before it was swung over and down into position.

ears ago but 55 years of service in a high lightning area is pretty good.

without a lot of 60Hz hash. It used to wipe out everything from 500KHz to 3

Prior to the pig being replaced, the only time I could use AM was during power outages, or after a hurricane. It wasn't dirty insulators, since it was the same before, during and after rain.

The old four foot Florescent lamps were even more impressive. They emitt ed RF at over 4 GHz. Ii used to repair LNAs and LNBs in my home shop. A qui ck test was to connect it to a receiver and point it at the ceiling. The no ise pattern on the bench monitor would change from random noise, to modulat ed noise. You could even see the signal level change on my test receiver.

As I'm sure you know, pole-mounted lightning arrestors also wreak havoc on RF receivers - well up into the 1900 MHz PCS band (though usually much wors e in 600/700/800, of course). That's the majority of what I find, but of c ourse I'm not usually working below 600 MHz, either. A bad arrestor clearl y shows on a thermal camera. (But in substations, FPL uses a ultrasonic "c amera". I don't know why? Something to do with corona, I suspect. (And w e did have a case at a generator station once that the spectrum analyzer co uld easily see, but the ultrasonic gear didn't detect it.)

Speaking of power lines.... I also once got dispatched on a broadband uplink interference case that tur ned out to be a small length of wire (maybe 6") that somehow got wrapped ar ound one of the phases and was just sitting there (this was medium voltage distribution). It was a LOT NOISIER than you might think! Of course, it w as only a couple hundred feet from the cell site, and at about the same hei ght, so that explains some of it. Maybe -60 dBm broadband? (The cell has high-gain antennas.)

Another (perplexing - at the time) dispatch involved a simple, plain-old CA TV leak -- but it was mid-span on the overhead wires! Binoculars confirmed that some squirrels had eaten clean through to the inner conductor.

Oh, and almost forgot another difficult interference case involving power p oles:

This time, it was a solar-powered data collector that FPL had installed on several poles as a test. It was some sort of telemetry unit that had a sma ll internal lead-acid battery and the solar cell kept it charged.

Well, long story short, FPL forgot it was on the pole.

Eventually, the battery won't hold a charge -- but about an hour after sunr ise, has charged just enough for the associated transmitter to start broadc asting broadband crap. That lasts until about 1 PM, when, the Sun angle to the solar panel is no longer adequate, and the whole device eventually col lapses -- until the next day!

Throw in a couple of overcast days (with no activity), and a short time win dow in which to detect the event is active (typically: 30-45 minute delay i n processing), and an hour's drive in good traffic to get there... and well , you can see this was quite a challenge to identify and finally get it off the pole!

Not fun.

Our internet died at the cabin in Truckee, and the cable TV got really terrible.

Really, that braid and plastic don't look very tasty to me.

on RF receivers - well up into the 1900 MHz PCS band (though usually much w orse in 600/700/800, of course). That's the majority of what I find, but o f course I'm not usually working below 600 MHz, either. A bad arrestor cle arly shows on a thermal camera. (But in substations, FPL uses a ultrasonic "camera". I don't know why? Something to do with corona, I suspect. (An d we did have a case at a generator station once that the spectrum analyzer could easily see, but the ultrasonic gear didn't detect it.)

turned out to be a small length of wire (maybe 6") that somehow got wrapped around one of the phases and was just sitting there (this was medium volta ge distribution). It was a LOT NOISIER than you might think! Of course, i t was only a couple hundred feet from the cell site, and at about the same height, so that explains some of it. Maybe -60 dBm broadband? (The cell h as high-gain antennas.)

CATV leak -- but it was mid-span on the overhead wires! Binoculars confir med that some squirrels had eaten clean through to the inner conductor.

Apparently it's Haagen Dazs to squirrels.

I'm jealous. You get to have all the fun. A marginally related power line noise story:

In about 2001, on the left coast, Sprint made what initially looked like a mutually beneficial deal with PG&E (Pacific Gas and Electric). They would use the PG&E transmission towers as cell site antennas in trade for tower lease payments. Sprint would save money by not having to build new towers and not having to deal directly with the various municipal planning departments. Of course, neither party bothered to ask their RF people if it would work.

Examples of two such installations from 2002:

These cell sites were PCS (1900 MHz) only with all the electronics on the ground. That means about 300 ft of 7/8 hard line between the radios and the antennas for about a 6dB loss which is huge and translates into a range loss of about 50% in both transmit and receive.

In an odd way, these loses were beneficial because the losses covered up the power line noise from the nearby HV power lines. When someone tried a TMA (tower mounted amplifier), it was impossible to communicate over the power line noise. Predictably, the range was about the same as with the coax cable losses. So, the choice was an expensive TMA or cheaper coax cable for identical but insufficient range. Sprint chose the cheapest. It's much like that today. The same systems are still running on some local PG&E towers with maybe a few more panels for added frequency bands. Sprint range and coverage still sucks but is largely hidden from customers because of a mutual roaming agreement with Verizon, which also uses 1900 MHz and CDMA, but not from PG&E power transmission towers.

So, what does this have to do with transformer noise? Part of the initial agreement for the use of the PG&E towers was for PG&E to replace or repair any of their equipment that produced interference to the Sprint radios. It turned out that some of the RF noise was coming from pole mounted transformers from nearby low voltage residential and industrial systems. No sooner had Sprint identified these source, the transformers were replaced by PG&E. We actually had a fairly clean RF environment for a few years, when the agreement was revised and the RF noise clause was removed.

In the 20-some years we've owned our house, the local squirrels have managed to chew through the power-line neutral wire from the pole-pig.

Twice.

Having high voltage in the house due to an open neutral is not fun. Fortunately there was no damage either time.

Sounds like it went feral

n RF receivers - well up into the 1900 MHz PCS band (though usually much wo rse in 600/700/800, of course). That's the majority of what I find, but of course I'm not usually working below 600 MHz, either. A bad arrestor clea rly shows on a thermal camera. (But in substations, FPL uses a ultrasonic "camera". I don't know why? Something to do with corona, I suspect. (And we did have a case at a generator station once that the spectrum analyzer could easily see, but the ultrasonic gear didn't detect it.)

urned out to be a small length of wire (maybe 6") that somehow got wrapped around one of the phases and was just sitting there (this was medium voltag e distribution). It was a LOT NOISIER than you might think! Of course, it was only a couple hundred feet from the cell site, and at about the same h eight, so that explains some of it. Maybe -60 dBm broadband? (The cell ha s high-gain antennas.)

CATV leak -- but it was mid-span on the overhead wires! Binoculars confirm ed that some squirrels had eaten clean through to the inner conductor.

Rodent damage to CATV hardline more common than you would expect. Especi ally in colder climates. It was a big problem for us, near Cincinnati, back in the '80s.

on RF receivers - well up into the 1900 MHz PCS band (though usually much w orse in 600/700/800, of course). That's the majority of what I find, but o f course I'm not usually working below 600 MHz, either. A bad arrestor cle arly shows on a thermal camera. (But in substations, FPL uses a ultrasonic "camera". I don't know why? Something to do with corona, I suspect. (An d we did have a case at a generator station once that the spectrum analyzer could easily see, but the ultrasonic gear didn't detect it.)

turned out to be a small length of wire (maybe 6") that somehow got wrapped around one of the phases and was just sitting there (this was medium volta ge distribution). It was a LOT NOISIER than you might think! Of course, i t was only a couple hundred feet from the cell site, and at about the same height, so that explains some of it. Maybe -60 dBm broadband? (The cell h as high-gain antennas.)

CATV leak -- but it was mid-span on the overhead wires! Binoculars confir med that some squirrels had eaten clean through to the inner conductor.

They chew it to sharpen their teeth.

Apparently you are as clueless as ever.

Woodpeckers can be a problem too:

pecially > in colder climates. It was a big problem for us, near Cincinnati , back in the '80s.

Many power and phone poles have required replacement, since the little r attlebrains pound away at the tops of the poles, until they work their way down to the through pole hardware. It was worse on the old creosoted poles than the pressure treated poles that are in use, today. They destroyed a fu ll foot of the pole at my previous home, until the anchor to the guy wire b roke free.