"Yuri Blanarovich" wrote in message
...

"Robert11" wrote in message
. ..
Hello:

I realize that everyone is going to probably write back and tell me I'm
crazy, but this is really driving me crazy, so let me ask, please.

I'm a retired engineer, but have never worked much with RF.

I have been putting up several models of Kidde and First Alert smoke
detectors in my new house recently.

Several different models, from both brands, both ionization and
photoelectric, some with the 9V battery, some with
the built in 10 year Li cell.

All exhibit the same performance:

About once every day or so, at totally random times, they give 3 or 4
Chirps, then nothing for approx another day or so.
This is not the indication that it gives for an actual fire; rather from
the skimpy instructions they include, an indication of needing a new
battery, or some internal fault the circuitry has discovered on its own.

All the batteries are brand new.

Here's what I'm leading up to:

About a quarter of a mile from my house, in a direct line, there's a Ham
operator with a massive mast of what must be pushing 100 feet in height.
Almost the kind you would see for a small commercial station. Has all
sorts of antenna and beams mounted to it.
I have no idea what freq's he operates at, and really don't want to ask
him.

This is obviously a chap who takes his hobby seriously, and probably
radiates at the max allowable power levels, I would guess.

Is there any possibility that if he points his array at my house, it
might radiate enough power to cause my problem ?

If not, any thoughts on what else might be causing these chirps from two
different mfg's., and several models ?

Much thanks,
Bob


Possible.
Smoke detectors not supposed to be radio receivers. In other words, they
should be immune to RF interference.

In a perfect world, yes. I had a problem with RF getting into a CO detector,
the plug-in AC powered kind. When I opened it up, I found there was only one
bypass cap on the circuit board, a 100 uF electrolytic. Adding a .1 to the
board, and a .01/1000V across the AC line fixed it. Somebody else with the
same problem ended up having to make a shield out of aluminum foil inside
the enclosure. His was AC, with a DC backup. Never had problems witj smoke
detectors, and the CO alarm is only affected at the 1KW power level. Also, I
am talking about less than 50 feet of separation here, not several blocks.

Tam/WB2TT


If they have wires going to them, they
work as antennas, pickup more RF and make things worse. Owner or
manufacturers should remedy the situation, usually bypass capacitor or
ferrite choke on the cables help.

Another solution, if there are no wires going to detector, is to insulate
portion of the circuitry with tape and wrap it in a aluminum foil, creates
the shielding and minimizes RF pickup.
Good luck.

Yuri, K3BU.us

I would approach ham and tell him about the problem. Most hams are decent
human beings and will try to sort the problem.