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Author Topic: Neighbor says I am on his alarm system  (Read 4683 times)
AE5JU
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Posts: 227




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« on: January 16, 2010, 01:36:20 PM »

My neighbor says, "I can hear you talking on your radio on the speaker on my alarm system."

My first thought is to tell him to call his alarm company, but I'm trying to be neighborly.  He is really appreciative that I am listening to his complaint and want to help resolve the problem.

Would a low pass audio filter help?  I'm talking essentially a low pass crossover, at say, 3 khz.

Suggestions?

Paul
AE5JU
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WX7G
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Posts: 5972




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« Reply #1 on: January 16, 2010, 02:20:55 PM »

Changing the nature of your signal (audio filter) will not help. Reducing the RF field at the neighbor's house will help.

To reduce the RF field you can reduce transmit power, move your antenna farther from the neighbor's house, or possibly change the type of antenna. I.E. from a vertical to a dipole. This may reduce common-mode current on the alarm wiring.

You might want to 'threshold' the problem. To do that reduce transmit power until the problem goes away. Then you know how much of a challenge you have ahead of you. If reducing power to one-half solves the problem that might be your solution. If reducing power to one-tenth is required you have a challenge ahead of you.

Legally the neighbor is responsible. He and/or the FCC cannot make you fix the problem. If you chose to go this route the neighbor can call the alarm company. They might have a fix ready to go.
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WB4BYQ
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Posts: 179




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« Reply #2 on: January 17, 2010, 06:03:36 AM »

look at this site for ideas.

http://www.olympixcorp.com/rfchoke/he-install.htm
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AE5JU
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Posts: 227




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« Reply #3 on: January 18, 2010, 08:18:19 AM »

More info - My antenna is closer to my home than this neighbor's home.  I get no intereference on any of the 4 TV's, 4 computers, 3 cordless phones, 3 stereo systems.  The FM yagi that feeds my living room stereo system is only 8' from my dipole.

My neighbor gets no interference on his phones, computer, TV, or stereo.  The problem is confined to his burglar alarm.  My voice, he says, can be heard, though distorted and unintelligable, on the alarm system's speaker.  

No other neighbors complain of interference, only this one guy.

He stated he does not want to call the alarm company to fix the problem as that will cost him a service call.  He told me I would have to stop operating my radio so as not interfere with his alarm.  I politely told him that is not going to happen, that my radio is a radio and operates as such.  His alarm system is not a radio, but operates as one.  Which did he think is the defective unit?

Well, this is going to get interesting.

Paul
AE5JU
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WX7G
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« Reply #4 on: January 18, 2010, 09:11:30 AM »

The alarm is 'defective' and I think the alarm company will not charge for a service call.

You might want to telephone the alarm company and discuss this with them. I would not be surprised if they have an RFI kit they will install at not cost.
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WB4BYQ
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« Reply #5 on: January 18, 2010, 04:58:34 PM »

Please advise us what happens.  this guy wants to be
hard to deal with.  good luck, and i would not stop operating,  he needs to do some work to rf proof his system.  that is the bottom line.

richard
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AE5JU
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« Reply #6 on: January 18, 2010, 08:39:25 PM »

I read the alarm company's name off a sticker on the window.  I found their website, contact info, and sent them an email.  I described his problem, and that I would be glad to assist by transmitting to test their work after they have installed RFI filtering.

But I am not going to stop operating.  It is obvious that the alarm system is the problem.  Nothing else is affected.

Paul
AE5JU
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AE5NE
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Posts: 91




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« Reply #7 on: January 19, 2010, 02:36:22 PM »

The "speaker" is likely a self-contained siren driver circuit and actual speaker (such as http://www.safemart.com/Sirens/Ademco-748-Dual-Tone-Siren.htm).

The signal coming from the alarm is 12VDC, DC on = siren on.  Usually delivered via long run of 18Ga 2-conductor jacketed cable.

Your Rf is probably being picked up, rectified by the circuitry, and driving the speaker element.

I suspect a 0.1uF capacitor placed across the screw terminals inside the "speaker" would fix the problem.
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AE5JU
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Posts: 227




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« Reply #8 on: January 20, 2010, 07:38:36 PM »

The "speaker" is likely a self-contained siren driver circuit and actual speaker (such as http://www.safemart.com/Sirens/Ademco-748-Dual-Tone-Siren.htm).

The signal coming from the alarm is 12VDC, DC on = siren on.  Usually delivered via long run of 18Ga 2-conductor jacketed cable.

Your Rf is probably being picked up, rectified by the circuitry, and driving the speaker element.

I suspect a 0.1uF capacitor placed across the screw terminals inside the "speaker" would fix the problem.


No, the speaker is a small 3" cone driver.  I tried a cap across the terminals, as well as an inductor in series.  No dice. 

There is nothing else in that speaker box but the cone driver.  The RF is probably being picked up elsewhere, going into whatever audio amp drives the speaker.
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W1ITT
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Posts: 146




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« Reply #9 on: January 21, 2010, 06:27:08 AM »

This neighbor sounds like a troublesome fellow.  While I agree that a .01 capacitor across the speaker, as well as a few clip-on ferrite chokes on some of the leads would be effective, I would not put them on myself.  If anything goes wrong in the future, guess who is going to be blamed, now and forevermore.  It's a judgement call, and you know the guy better than anyone on eHam, but his uncooperative demeanor sends up a red flag for me.  Part 15 of the rules and regs is on your side.
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AE5JU
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« Reply #10 on: January 22, 2010, 07:42:17 AM »

Part 15... yes, it is.  ;-)
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WX7G
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« Reply #11 on: January 22, 2010, 08:26:48 AM »

Have you done a threshold test? If reducing power by 1/2 fixes the problem the alarm company does not have a huge challenge to fix the RFI. It reducing power by a factor of 10 is required they have a job ahead of them.

Say 1/2 power fixes the problem. That might be your solution. It also says that moving the antenna farther away might be a solution.

I have found it works best with neighbor RFI to explain nicely that I am not required by the FCC to fix the RFI or to change my station in any way. I do say, however, that I will make a reasonable effort to help. This consists of moving my antenna and possibly reducing power. I will also supply enough ferrites and filters. That can run a couple hundred dollars.

with one good neighbor my TX would set off his alarm which would then dial the police. The alarm company came out at no expense and installed an RFI-hardened unit. Problem fixed.

My TX was still getting into his very large and expensive (dozens of wires) TV and audio system. As watching TV was my (hermit) neighbor's life I decided that reducing TX power was the way to go.
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N9AVY
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Posts: 66




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« Reply #12 on: January 22, 2010, 08:14:53 PM »

As an alarm professional, I've had to deal with all sorts of RFI problems. Many of the alarm problems can simply be fixed by making sure the alarm panel is properly grounded at both ends.

The speaker problem sounds like it might be the cable run from the panel to speaker location acting like an antenna. The best fix would be to replace the cable with either shielded cable or twisted pair alarm wire. With the shielded cable only the shield at the panel end needs to be grounded.

If your neighbor has one of the newer wireless alarm systems with the speaker inside the plastic box/keypad; then, there will be problems.

Good luck !
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AE5JU
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Posts: 227




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« Reply #13 on: January 23, 2010, 08:44:09 PM »

No, the alarm panel is by his front door.  The speaker box is just that, a little plastic box about 4" x 4" mounted about 15' away down a short hall.
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K5END
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Posts: 1309




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« Reply #14 on: January 25, 2010, 02:24:49 PM »

Wire cutters would fix it.  Roll Eyes



Seriously, kudos for being a good neighbor.

Since choking and capping the speaker did not work, I wonder if the problem is in the power supply or the amplifier circuitry.

Grounding and shielding of his system are the next things I would look at, in that order.
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