RFI causing CO Monitor to "Alarm" ?

[K8AG]

Many years (decades) ago I had my first apartment in a new building. I set up a simple random wire antenna around the room. When I keyed up on 40M my smoke detector would beep in rhythm. Although the detector was a permanent install, it was battery powered. Undaunted I removed the battery and went about having a nice 40M QSO. That was until a neighbor pounded on the door shouting fire.

Apparently mine wasn't he only smoke detector that I was triggering.

I quickly replaced the battery and rushed out the door to stand while the local FD checked the building.

Needless to say I found it necessary to fashion an outdoor antenna for 40M operation from then on.

Oops.

73, JP, K8AG

[N4UP]

Many years (decades) ago I had my first apartment in a new building. I set up a simple random wire antenna around the room. When I keyed up on 40M my smoke detector would beep in rhythm. Although the detector was a permanent install, it was battery powered. Undaunted I removed the battery and went about having a nice 40M QSO. That was until a neighbor pounded on the door shouting fire.

Apparently mine wasn't the only smoke detector that I was triggering.

I quickly replaced the battery and rushed out the door to stand while the local FD checked the building.

Needless to say I found it necessary to fashion an outdoor antenna for 40M operation from then on.

Oops.

73, JP, K8AG

Interesting. It is nice when we can correlate our transmissions to particular RFI issues; that way we can try to fix them. But what I worry about are "effects" that are not so easy to correlate. For example, did my RF have any effect on that large capacitor that just failed in my outside air conditioning unit? I would think, most likely, it failed because of the stress of so many 100F days in a row. But maybe ( maybe ) my RF encouraged the failure. Probably not, but you never know. I suppose these are just things we have to take in stride. As a homeowner I am accustomed to things failing, all by themselves, but now that I am back on the air after many years I am wondering just how much effect my RF is having on things.

Seems like it used to be simple in the "old" days. Put a low pass filter on the radio output and a high pass filter on the TV antenna leads and that was that. Most older "appliances" didn't have CPUs or anything that would be vulnerable to modest amounts of RF. Now it seems like most electronic items are more vulnerable to RF, or maybe it's just my imagination.

Of course living alone means I may be missing some RFI problems. For instance I would not have known that my RF was messing up my digital TV signal because I don't watch TV and go on the air at the same time, but when I later watched a program from the DVR then I knew I had a problem ( and it correlated nicely with my log book ) ( easily fixed with ferrite beads on the coax from the satellite dish into the DVR ). But what about my non-radio-room computers, stereo system, etc.? On the other hand, if there is no "evidence" of RFI then I shouldn't worry about it.

[KL7AJ]

Just wondering if anyone else has encountered RFI that apparently causes a CO monitor to alarm? Scared me half to death the first time it happened. Has now happened three times. For me, so far, it only happens on 40 meter CW and only on longer QSOs. It does not happen on other bands and it does not happen on short QSOs. And yes, it happens every time I have a long QSO on 40 meter CW and never goes off otherwise. When I stop transmitting for a few minutes, the alarm stops. Makes me very reluctant to chat on 40 meters !!

My antenna ( rotatable multi-band dipole ) is in the third floor attic, the station ( running 500-600 watts ) is on the second floor but not directly under the antenna, and the CO monitor is also on the second floor, but just "under" the antenna. Fire alarms do not go off.

Been back on the air since May ( 2012 ) after a long absence, so it's a new station. There were a couple of RFI problems that were easily solved with a low-pass-filter, line isolators, and ferrite beads. But not sure what I can do to a CO alarm that is battery-powered and not connected to anything else, that would enable it to still function as a CO monitor. I don't really want to pull the batteries every time I want to chat on 40 meter CW.

The same solution for this generally works on GFI outlets that trip with R.F. and the like. If you're electrically competent, disassemble the outlet the CO detector is plugged into, insert a toroid core on the power leads right at the outlet, and reassemble. Takes care of nearly every R.F. problem, in most cases.

Eric

[KD7HB]

The CO monitors I had to place in my rental property have a 10 year life. There is an electronic component that slowly degrades over the 10 years and then disabled the device. You might want to check the manufacture date on yours and see if it has much life left in it. At $10.00 for a new one, might be better to just toss it.

Paul, KD7HB

[N4UP]

The same solution for this generally works on GFI outlets that trip with R.F. and the like. If you're electrically competent, disassemble the outlet the CO detector is plugged into, insert a toroid core on the power leads right at the outlet, and reassemble. Takes care of nearly every R.F. problem, in most cases.
Eric

Thanks. The CO monitor is batteries-only, not connected to any outlet. I have already removed it, pulled the batteries, and stored it in the garage.

[N4UP]

The CO monitors I had to place in my rental property have a 10 year life. There is an electronic component that slowly degrades over the 10 years and then disabled the device. You might want to check the manufacture date on yours and see if it has much life left in it. At $10.00 for a new one, might be better to just toss it.

Paul, KD7HB

Thanks. I just checked. 11/2006. I had not thought about lifetime. When I sell the house I will probably re-install this one as it should still be good.

[W5TTW]

Yep. In my previous home, the plug-in CO monitor would start squawking whenever I worked CW on 40M. The monitor was on the 1st floor with my shack on the 2nd. (Not overhead.) The antenna was an OCF dipole in the back yard, about 50' away. I recently moved and do not have a CO monitor in my new digs. However, I now set off three zones of my lawn sprinklers when working on 40. Maddening.