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[RFI] RFI Troubles

To: <rfi@contesting.com>
Subject: [RFI] RFI Troubles
From: Larry Crim" <k4ab@email.msn.com (Larry Crim)
Date: Fri, 22 Dec 2000 21:28:44 -0600
.>  I also recommend the ARRL RFI Book

I also recommend a good attorney.  A good place to start is the ARRL
volunteer counsel team.  It may wind up costing you some bucks, but well
worth it if the battle starts getting dirty...as I have witnessed.


Larry K4AB

-----Original Message-----
From: Hare,Ed, W1RFI <w1rfi@arrl.org>
To: 'gm@netsync.net' <gm@netsync.net>; rfi@contesting.com
To: <rfi@contesting.com>
Date: Friday, December 22, 2000 18:04
Subject: RE: [RFI] RFI Troubles

>Hello, Gerry,
>> and my neighbor there has been complaing about RFI
>> from my HF rig. His main complaint is that I'm coming > through the
>speakers on his computer.
>One first good step for you and your neibhbor to take is for you to both
>understand the differences between RFI caused by rules violations at your
>station and that caused by the inability of some (most?) consumer equipment
>to function properly in the presence of strong radio signals.  The FCC
>requires you to correct interference to other radio services caused by
>violations at your station, but the FCC rules do not address "fundamental
>overload" of non-radio equipment. The latter is really a local problem.  In
>most cases, a ham may want to help out, but this becomes a matter of your
>helping your neighbor find a solution.
>In the case of interference to non-radio devices, the FCC RFI material is
>pretty clear -- the device is improperly functioning as a radio receiver.
>This suggests that the cure in that case would be to apply the necessary
>filtering and/or shielding to the affected equipment.
>ARRL publishes a pamphlet jointly with the Consumer Electronics
>It is available at:
>The FCC information about RFI is also valuable. See:
>I also recommend ARRL's general info about RFI at:
>Start by reading the info to give yourself a good understanding of the
>problem, then print a copy of the pamphlet and the FCC material and give it
>to your neighbor. RFI problems sometimes get rather "heated," and this will
>give things a chance to calm down. You should also correct any RFI problems
>to your own equipment.  It will really help your neighbor understand that
>your own computer works well, the problem must be on his end.  Once you
>done so, it is time to talk things over with your neighbor.
>Start this conversation by explaining that interference to other radio
>services can be caused by problems at your station and that the FCC
>you to operate your station legally.  Your neighbor will be listening at
>this point because you are telling him or her what YOU need to do.  You can
>then explain that you have put the necessary filters on your transmitter
>(get a filter for your transmitter and install it, whether you need it or
>not.  You can then point to it with pride.)
>Next, you can show him your station (clean it up first!) and the filters
>have put onto your own equipment.  This helps him understand that the
>problem is on his end and that the cures you suggest will do no harm.
>Then, explain that you have checked your station throroughly.  Point out
>that the FCC's material identifies that for interference to non-radio
>devices (their material specifically names computers), the cure must be
>applied to the computer.  At this point, I suggest that you let your
>neighbor know that even if the interference is not caused directly by your
>station, you would like to be a good neighbor and help him find a cure.
>This usually keeps him talking.
>Interference to computer speakers is generally an audio problem.  For
>completeness, see:
>The cure will usually involve common-mode chokes.  For computers, obtain
>about a half dozen F-140-43 ferrite cores.  For larger wires, you may need

>the F-240-43 size.  For HF, you need some inductance to make a good
>common-mode choke, so don't substitute those handy clamp-on ferrite beads.
>You will need about 10 turns of wire on the choke.  Some computer speakers
>are amplified.  This generally requires that you put a ferrite on the end
>each of the speaker wires connected to the computer and at the speaker end,
>as well.  Most of the computer speakers "daisy chain" from one speaker to
>another.  The speaker may have an ac "wall cube" power supply. In that
>might be worth trying a core on the power supply lead, right at the
>These cores are available from Palomar and other distributors. See
>http://www.arrl.org/tis/tisfind.html to look up addresses, phone numbers
>web sites.
>This quick email is an overview.  Go through the more detailed ARRL and FCC
>material.  I also recommend the ARRL RFI Book
>(http://www.arrl.org/catalog/6834) for more info yet.
>Good luck.
>Ed Hare, W1RFI
>Ed Hare, W1RFI
>ARRL Laboratory Supervisor
>225 Main St
>Newington, CT 06111
>Tel: 860-594-0318
>FAX: 860-594-0259
>Internet: w1rfi@arrl.org
>ARRL Web: http://www.arrl.org
>ARRL Technical Information Service: http://www.arrl.org/tis/
>-----Original Message-----
>From: gm@netsync.net [mailto:gm@netsync.net]
>Sent: Friday, December 22, 2000 5:27 PM
>To: rfi@contesting.com
>Subject: [RFI] RFI Troubles
>I wonder if I could get some advice on an RFI problem. I live in an
>apartment that is part of a large house. There is one other apartment
>here too, and my neighbor there has been complaing about RFI from my HF
>rig. His main complaint is that I'm coming through the speakers on his
>computer. My main antenna is a Butternut HF5B 2 el mini-yagi that is
>mounted up on the roof. The bottom of the antenna is roughly 15 to 20
>feet above his computer, and 5 feet away horizontally.
>My first question is: In the eyes of the FCC, is my antenna too close to
>his apartment? I have heard some people say that the FCC expects a ham's
>antenna to be at least 50 feet away from any neighbors, otherwise the
>ham can be blamed for interference. Is there any truth to this? I
>normally run 100 watts output, and I know that my neighbor's apartment
>is within the FCC's RF saftey limits. I occasionally run 500 watts for
>DX pile-ups, which is also within limits, but I only do it when the
>neighbor is out. It's very possible that the FCC will be coming here to
>look at the problem, so I need to know if my antenna is too close (at
>100w), and if I could be held responsible for the RFI problem.
>I also have dipole for 30 and 40 meters, but I only use it when the guy
>is out. That antenna is roughly parellel to his 2nd floor apartment, and
>about 20 feet away from it. There isn't enough room here to put up
>anything better.
>As for cleaning up the RFI, I have not been able to do much since my
>neighbor is not very cooperative. The problem is from HF fundamental
>frequencies. I'm coming through the speakers on his computer, which he
>insists on leaving on 24 hours a day. He won't turn off his amplified
>speakers - not even before going to bed at night. He uses rabbit ears
>for a TV antenna, and we are in a fringe reception area. His TV is at
>least 30 feet from my antenna, and I clobber every channel. He also says
>I come in through the phone line.
>Since his main complaint is with the computer speakers, that is where I
>have been trying to help him so far. I don't seem to cause any
>interference at all on his monitor. I tried using ferrite beads on
>various speaker cables and mananged to reduce the interfence by maybe
>50%, but it is still very noticeable. I only had 2 beads, so I couldn't
>do as much as I wanted, but I doubt that beads alone would have done the
>job. He has a total of 5 speakers, with 2 separate ampifiers. At one
>point I grabbed a hand-full of the speaker wires and the interferece
>dropped WAY down. I'm thinking I might be able to wrap several turns of
>wire around these cables, then ground the wire to simulate the same
>thing. Does that make any sense? His computer is grounded btw. I
>grounded it because the AC wiring in this place is not grounded.
>For the phone line, I will try a bead or a torroid core. For the TV,
>I'll try a high-pass filter, but I have doubts that it will help much.
>It's been hard to do much of anything because the neighbor isn't very
>cooperative. We agreed yesterday to work on the problem at noon today,
>before he would go to work at 2 pm. He wouldn't answer his door or his
>phone when I tried to reach him several times between 12 and 1:30.
>Finally, just before he had to leave for work, he anwered his door. He
>said he "must have been sleeping" earlier. This is typical for this this
>guy, - it's happened before. So, I'm about ready to just go ahead and
>operate and let him make complaints to the FCC. It's easier than dealing
>with his lousy attitude. I need to know first though if my antenna is
>too close to him. I'll probably be able to get in his place one last
>time to try a few things though, so any advice on solving the RFI
>problems is also appeciated. I've never had problems with RFI before, so
>all of this is new to me.
>Gerry KA2MGE
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