I have a customer who is an amateur radio operator and is complaining that whenever he is transmitting he trips the smoke detector we installed (System Sensor 2012HA). He is asking for a smoke that is better designed for RF Immunity.
Almost all the motions I have seen have some spec listing RFI (typicall
30v/m 10-1000Mhz) but I have not found any such spec on any of the smokes I have looked at. (System Sensor, GE-Interlogix, DSC)
Anyone have any suggestions for a smoke detector in a RF rich environment?
Anyone done an install at a radio station (the transmitter not the studio) and what did you use?
Use shielded cable between the Smoke(s) and the control... In most cases, the wiring acts as an antenna feeding RF into the detection device or the control (sometimes BOTH)............ Regards, Russ
I also avoid smokes with heats on them unless there the new style thermals as they often picked upRF and static easy .Had a case were kids were running on a rug picking up static on them selves then reaching up and tuching the metal heat on the smoke . Im curious he is having problem as well I maintain a 5000 watt am radio station WAVL910 with system sensor smokes no problem and amatuer radio is limited to 2000 watts.
Probably HF, 10 (28MHZ) & 15 (21MHZ) meters were the hardest to keep out of tvs, cheap phones, stereos etc.. One big problem some Hams create for themselves when it comes to RFI, mounting HF antennas in their (This is done because of CC&R's that restrict outside antennas) attics... There's nothing like radiating a 100+ watt 28MHZ signal 6ft away from all of your Low & High voltage wiring...
If the commercial broadcast antenna is located some distance from the building, it may not be as bad as a Ham running 500 watts into a multi-band Yagi 20ft above his/her roof top...
Those HAM guys always crack me up. Whenever something doesn't work with their giant transmitters nearby, it's OUR problem. Here's an idea, Mr. Ham, use the Internet to talk to that boring guy in Timbuktu you'll never meet.
How long before that spectrum is annexed by the Feds anyway?
My smokes are in the 2 directional transmitter huts themselves geting the full hit. I even have the ademco 5800 wireless contacts running in the huts back to transmitter building and no problems
As an Ham radio operator and an alarm technician I have seen this occurred many time
in the time of the 1500 and such line of dsc, putting a capacitor (10 uF) across the zone lead at the detector(in parallel of the end of line resistor) would cure the trouble...
now I don't know what of panel you have but this could do the trick...
one other time the capacitor trick could not work so we coiled the wiring on a ferrite toroid...
hope this help
"Eyeball Kid" a écrit dans le message de news: EwXXg.42$ snipped-for-privacy@newsfe21.lga...
In the early days of television, people used to complain about ham radios causing interference on their TVs. From what I hear, the problems were mostly due to poor design of the TVs, rather than the ham radio guys doing anything wrong. Even so, hams would sometimes go to their neighbor's house and use their technical expertise to add the necessary filtering to the TV sets, just to be good neighbors.
I am not a ham, but there do seem to be a couple things the OP could look into:
Is it the smoke detector or the control panel that's getting tripped? Remove smoke detector, install EOL at smoke location, and key the mike: if it trips, it's obviously not the smoke detector.
Is the control panel grounded? We could argue about whether grounds attract lightning strikes or not, but if the circuitry is picking up large amounts of RF, the RF has to have somewhere to go.
It's not me, it's the world that has the problem :-0)
I guess I don't understand what the hobby is all about. If your idea of a hobby is putting unsightly equipment on your home and bringing down the look of the neighborhood while at the same time spewing transient RF signals that are disruptive to innocent folks lives -- have at it.
I have battled RF problems for years. I have installed more > 1uH chokes than I care to mention. Since Y2K I have only had my ass eaten alive by RF/EMI on a DSC 4020 AML loop with fire. The only thing I can say is if you're trying to trouble shoot the problem and you're convinced it is RF/EMI related you're pretty much pissing up a rope without a properly scaled OSCILLOSCOPE and an engineer that knows how to read it. The System Sensor smoke you mention seems to be end of life. I would try to talk to my factory rep for what ever replacement brand you pick and put them on the spot to see if they will put their money where their mouth is. Tell them you have an installation that needs to be RF proof and see if they will bite and promise (in writing) to send a (real) engineer to fix their product if it fails in that environment (and MOST IMPORTANTLY PAY YOU FOR YOUR TIME SPENT). I can't tell you what happened with DSC officially but I can say that it got fixed and DSC did the right thing (a.k.a. hush up).
I'm still waiting to hear from the customer in person (the probelm was forwarded to me from our service dispatchers) one of the questions I had for him was what freq is he using to make it trip consistently and how much power is he puttinginto the antenna and where the antenna is located in relation to the smoke (and it's wiring). I'd like to arrange a site visit to see for myself.
Rewring an existing system with shielded wire seems a little impractical and my first thought was to try an eliminate the problem by adding a combination of caps and or chokes at both ends of the wire (at the panel and at the smoke)
One of the questions I want to ask the customer is when he manages to trip the system does the sounder in the smoke go off or just just the siren (in which case he is just tripping the zone on the panel (I suspect it's an Ademco Vista but I haven't pulled the file)
Years ago I had a problem with a customer/ham who was able to arm and diarm his system by keying his mike. It was an old DSC CP-10 style panel (arming/diarming by mom contact in this case a DCU-20 Keypad) and I solved that one by taking the excess wire at the panel end of the arming input and wrapping it around the shaft of my instrument screwdriver to form a poor man's inductor.
Hopefuly this one is as easy.
It strikes me as curious that RFI is a commom spec on motions but unheard of on smokes....
One thing I can tell you is that,when come a time,that you hear in the background noise stack between 2 large power transmission from somewhere in Arizona or Utah,a faint signal,coming from south Africa,transmitted from a low power transmitter (we also do that..) and you are able to make the QSO and send your QSL card on the next day..you just cant understand the feeling of achievement you have...all the hard work for building this highly sensitive receiver,and the time to build the Low power transmitter,and of course,learning of that damn Morse code...followed by installing that tower(and having your pal next door asking: when will the alien will answer you back?) tuning this invert v antenna to have a 1:1 swr ( I know I will achieve it one day,not just in my dream),all this work just to exchange a " HI! what's your call letter again? "(not really what I would have sent but I left this part in plain English not in hammish)..
when this come to you,you now understand what's the hobby of ham radio,before that,you are just simple nerds trying to fiddle some wire an tube,trying to make something out of this mess....
"G. Morgan" a écrit dans le message de news: snipped-for-privacy@4ax.com...
Just a follow up for anyone who was curious. I visited the premises and found the customer was able to trip the zone the smoke detector was on when tranmistting on either 3.8 MHz or 21 MHz (running about 700 watts). Interestingly when he did this the siren on the system sounded but not the piezo on the smoke detector (leading me to believe he is not tripping the detector just the zone)
I pulled the detector off the mount and found the customer had installed a snap on ferrite around the wires. Went to the panel and found he had also put a ferrite around the telephone line (about the only wiring that was accessible without opening the panel). I moved that ferrite on to the pair running into the zone being tripped and we ran a test.
No more problems at 21 MHz but he was still able to trip it at 3.8MHz. So I took my mother's approach to cooking ("If a little makes it good - a lot will make it better") and installed a 2nd ferrite that I had happened to bring along. Voila - no more problem - I told him to spend the weekend trying to make it trip and went home. Almost a week later and I haven't heard from him.
So the lesson learned is - RFI Problems are easily solved with Ferrites!
The ferrites he had are from DX Eng> I have a customer who is an amateur radio operator and is complaining
Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.