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Author Topic: I have tons of interferrence where I live.  (Read 5171 times)
KE7IZL
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Posts: 47




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« on: August 01, 2011, 06:39:31 PM »

I have a ICOM PCR1000 computer controlled receiver (it can practically receive everything in RF below 1GHz and above 500KHz, with only cellphone band being blocked out). It's really great in the HF range, as I can tune to any band inside or outside of the ham bands and listen (often outside ham bands, I get digital modes meant to convey computer data or control or telemetry signals that I don't even know where they come from, or what type of mode is used, most likely proprietary from some industrial or utility place).

As cool as that is though, I find in the last couple years that interference is increasing in the HF region of the radio spectrum. One source I can identify is in the 14MHz ham band (but also well beyond), and it's my LCD computer monitor with interference over a band that is like 1 or 2 MHz wide! But most of the interfering signals aren't anything I can figure out. It's most likely consumer electronics like computers, digital TVs, home audio systems, etc. And that's compounded by the fact I live in an apartment with a couple dozen units, and people these days tend to like electronic gadgets, so I'm living basically in a hotspot or RFI. That sucks! I hear FCC makes laws that consumer electronic devices that produce unintentional RF radiation as a byproduct of operation are SUPPOSED to be designed to not interfere with reception of intentionally radiated signals (like having proper Faraday-shielding using a metal case instead of a plastic one, ferrite beads on their external wires, etc). But this interfering with received signals is exactly what's going on here. I'd love to find out the source of the electronic noise I keep getting (it effects, in one form or another, almost all the HF spectrum). I'd love to find the source and tell the people to shut off their electronic devices, and that I'm gonna report them to the FCC if they don't stop interfering with my radio hobby, but I'd probably have to report everyone in my neighborhood if I took that course of action.

I just want some tips on how to reduce the interference when I'm tuning through the HF bands.
Any ideas?
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KE7IZL
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« Reply #1 on: August 04, 2011, 09:12:47 PM »

Still need help finding and removing the RFI from where I live. It makes my SWL and ham hobbies, nearly impossible.
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K5CQB
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Posts: 223




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« Reply #2 on: August 05, 2011, 02:36:58 PM »

I'd love to find the source and tell the people to shut off their electronic devices, and that I'm gonna report them to the FCC if they don't stop interfering with my radio hobby, but I'd probably have to report everyone in my neighborhood if I took that course of action.

Not only would you have to report all of your neighbors but they would all hate you for it.  Knocking on someones door and telling them they have to do something is usually very ineffective and usually results in their doing the opposite.  Believe me on this one, I'm a police officer;)

You'll catch more flies with honey than vinegar.  When neither works might I suggest you design your station around as much of the interference as possible.  You may also be surprised that a lot of the interference may be coming from your own residence.  Check out YouTube for some really good demonstrations on finding RFI.

http://www.arrl.org/sounds-of-rfi
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K1TWH
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« Reply #3 on: August 05, 2011, 05:05:37 PM »

Ben,
___You didn't mention the type(s) of antenna(s) you are using with the IC-PCR1000.  The antenna and its placement can make a difference.  Do you have room to space the receive antenna away from other residences (as well as yours)?  Are you using an active antenna?  If its an active whip, it needs to have a 'noise' ground on its feedline.   Ferrite beads sound like a good idea till you realize the input impedance of the active whip is about 100,000 ohms.  That about 100 ferrite beads (or more) to place a 3dB hurt on the noise. 
___Check out the Wellbrook Receiving Loops.   They cost $$$, but are self balancing with respect to noise, and do not respond to electrostatic fields nearby (far away RFI has achieved the normal balance between electrostatic and electromagnetic fields and gets picked up by all antennas, unless they are dierectional and not looking towards the RFI source).
___Let us know your antenna set up.  Also, the PCR1000 is very easily overloaded, so it can take strong signals and spread them to frequencies that they aren't really on.
          73,  Tom  WB1FPA
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KE7IZL
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« Reply #4 on: August 05, 2011, 07:29:20 PM »

Ben,
___You didn't mention the type(s) of antenna(s) you are using with the IC-PCR1000.  The antenna and its placement can make a difference.  Do you have room to space the receive antenna away from other residences (as well as yours)?  Are you using an active antenna?  If its an active whip, it needs to have a 'noise' ground on its feedline.   Ferrite beads sound like a good idea till you realize the input impedance of the active whip is about 100,000 ohms.  That about 100 ferrite beads (or more) to place a 3dB hurt on the noise. 
___Check out the Wellbrook Receiving Loops.   They cost $$$, but are self balancing with respect to noise, and do not respond to electrostatic fields nearby (far away RFI has achieved the normal balance between electrostatic and electromagnetic fields and gets picked up by all antennas, unless they are dierectional and not looking towards the RFI source).
___Let us know your antenna set up.  Also, the PCR1000 is very easily overloaded, so it can take strong signals and spread them to frequencies that they aren't really on.
          73,  Tom  WB1FPA

Random long wire antenna strung up along a hallway is what I'm using for an antenna.
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AE4RV
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« Reply #5 on: August 06, 2011, 04:02:40 PM »

Get it outside for starters.
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W8JX
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« Reply #6 on: August 07, 2011, 05:11:52 PM »

Get it outside for starters.

And at very least too...
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--------------------------------------
You can embrace new computer/tablet technology and change with it or cling to old fall far behind....
K1TWH
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« Reply #7 on: August 08, 2011, 03:38:57 AM »

___The only indoor antennas I've used that allowed reasonable reception have been shielded loops.  My first was a AL4 sitting atop a Drake SPR-4 receiver 30 years ago.  The last was a Wellbrook AL1530 a few years ago.   Its generally much cheaper to place the antenna out doors (considering a Wellbrook can set you back $350-400. In the latter case, the loop seemed blissfully unaware of all the noises generated by my computer, scanner, printer, laptop power supply, Astron SS-25 power supply, Panasonic microwave oven, downstairs bathroom light dimmer, electronically run Samsung front loader washer, and even the 15.734 KHz TV high voltage 'birdies' were pretty far down when compared to a wire in the attic.   My antennas are out in the trees now, even for my receivers (IC-PCR1000 & FRG-100).  Better reception, less $$$.   You could say the sale of the loop funded at least one of the receivers...
___A small version of the G5RV would serve the PCR1000 well.  You need two 25' pieces of wire, and perhaps 16-17 feet of TV twinlead.   Plenty of other choices, and lots of Web based articles showing 'how to' make antennas.
___You're right, the trend has been ever increasing noise levels.  I don't think the trend is going to change any time soon.   
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KE7IZL
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« Reply #8 on: August 08, 2011, 12:55:22 PM »

Get it outside for starters.
You see that's the problem. I live in a rented apartment and I'd have to get permission from the owner of the building before I start stringing up wires on the outside on his building.
Same reason I have been unable to get a good ground for my HF rig. I live on the SECOND FLOOR of the apartment. And wires long enough to reach a grounding rod would be long enough to possibly act like an antenna. So I face issues like possibly needing an antenna tuner AND ground tuner.
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AE4RV
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« Reply #9 on: August 09, 2011, 07:09:04 AM »

When I lived in an apartment I put up a 20M dipole in the back yard in plain sight. No one said anything*. Sometimes I ran a ground wire to a cold water pipe but most of the time I didn't bother.

Or you could get permission.

It is possible to enjoy ham radio in an apartment, of course. But it is much easier in a house.

A random wire inside an apartment is pretty close to a worst case scenario for RFI.

73, Geoff

* Not entirely true. A friend who lived upstairs complained almost every time that I transmitted with more than 15 watts because of interference to his stereo, TV, computer speakers etc. All of which were on 24/7 and he only left the apartment to do occasional social things. I really should have embraced QRP more than I did back then...
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KE7IZL
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« Reply #10 on: August 09, 2011, 01:03:13 PM »

In order to check if a given RFI signal is getting into my receiver via serial control cable, audio, or power cable (not the antenna) is it a good idea to listen on the same frequency with antenna unplugged? Or is it more often that a combination of one or more of these cables and the antenna wire are working together to make an extremely complicated antenna that is "tuned" to the interference, and that removing a cable or antenna wire and stopping the RFI may not actually indicate that the signal was coming through that way but rather that I just "detuned" the complicated antenna by removing one of its "elements"?

Please let me know here, as I'd really like to know what route or routes various RFI singals are getting into my receiver. I wanna buy ferite snappon beads but only as many as needed to kill the RFI (not necessarily waste money and put them on every wire/cable going to my receiver).
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KC9TNH
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« Reply #11 on: August 22, 2011, 12:52:36 PM »

Please let me know here, as I'd really like to know what route or routes various RFI singals are getting into my receiver. I wanna buy ferite snappon beads but only as many as needed to kill the RFI (not necessarily waste money and put them on every wire/cable going to my receiver).
As to route(s), the best route in is your antenna; what was it Geoff said, "electrons are lazy and will take the path of least resistance...." Besides, the chokes will probably do better work mitigating at the noise source rather than having you collapse your whole defense strategy back to your rcvr.  Couple quick background things:

- when re-roofing years ago, down came the nasty old vertical mast from previous owner, XYL insistence and I agreed, mostly because one thing previous guy'd done was install one of the most robust & available ground systems in any 70's built house which I loved, who cared about the mast? When it came time to get something up, mostly lot considerations drove an OCF dipole (before that it was end-fed "random" wire w/tuner thrown into maple tree out front, radiator at about 43' effective length).
Point to all this is that very shortly after they go up, wire antennas are often soon forgotten, unless you're tripping people or they've got to duck. Now going back to what AE4RV mentioned: ask permission to run something outside - it need not be a football field long, you've got a tuner (right?). Done right, they are really benign, once up most people don't even see them, and you'll greatly increase your performance. What's worst that could happen, they say no? You can even go online to run a basic RF assessment to go armed (figuratively) with your case that you'd pose no risk to anyone.

- once, not long after a sage CW friend mentioned how nice & quiet it was on his QRP rig when the whole area got blacked out one time I got to experience the same thing. Quietude, Bliss On Battery. Still, on 20m at times I could hear the jake-brakes from the semi's comin' off the highway into town when they hit the speed-limit sign 1-1/2 miles away.
Point is that this stuff can come at you from anywhere, it's not goin' away.  But, in my experience (this is TroubleShooting-101, not just radio) one really does have to gird up the patience and, rig running, start unplugging things one-at-a-time and contrast the result, very likely more than one device contributes its share.  This will tell you initially inside what the biggest culprits are and you can start "choking" the critters. And don't rule out the most innocuous little device if it has an electrical connection or does anything electrical. And if it turns out to be a neighbor's device, being neighborly (with ferrites in hand) can really go a long way.

Having done a fair amount of that, I'm down to 1 known household issue, and it will get placed in the daughter's BR & turned on only when she's home on leave after I replace that CRT megalodon noisemaker with a proper LED/LCD TV for daily use. I wonder how many of your neighbors have standard big-footprint televisions still operating. Yes, I've got some snap-on chokes scattered about the house on things too. Now if I could just get those trucks to drive through a TEMPEST-approved tunnel on the way down the hill...

Good luck!  Smiley
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73
Wes -KC9TNH
"Don't get treed by a chihuahua." - Pete
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