[RFI] RFI to new photoelectric smoke detector

[Dale Svetanoff]

Kelly,

While I do not have info for you on RFI-proof smoke/fire detectors, I can
tell you that at least 1, and possibly more than 1, semiconductor device is
getting forward biased by your RF.  Your options:

1.  Reduce xmtr power (probably not what you had in mind)

2.  Move antennas further away from the house (probably not easy to do)

3.  Install internal shielding in the detectors (which will probably void
the warranty and may result in non-operation - not a recommended approach)

The one good thing is that those detectors are battery-powered, so there is
no power line "antenna" to consider.  I imagine that a detector contained
in an all-metal housing would be good, but try to find one.  I hope someone
on the list can suggest a detector that is known to be RFI-proof at the 1
kW power level in the HF region.

Also, please do try 80m on the dipole.  It will likely cause the same
results, but you won't know unless you try it.  Please report the test
results here.  Thanks.

73,
Dale Svetanoff, WA9ENA
Sr EMC Engineer
E-N-A Systems, LLC
Specializing in shielding applications, system grounding, and lightning
protection


> [Original Message]
> From: Kelly Johnson <n6kj.kelly at gmail.com>
> To: RFI List <rfi at contesting.com>
> Date: 11/4/2012 9:23:34
> Subject: [RFI] RFI to new photoelectric smoke detector
>
> My inlaws just bought us a couple of new photoelectric smoke+fire
> detectors.  They are both 9v battery powered First Alert model
> SA710CN.  They are sensitive to RFI when I run 1KW.  I did not have
> RFI with my older (non-photoelectric) smoke alarms and I do not have
> any other detectable RFI issues in my home.  The issues are there on
> multiple bands with my yagi (65 feet above the house) pointing in
> multiple directions.  I have not tried 80m with my lower hanging
> dipole.  I can easily replace them, but with what?  Anyone have
> smoke+fire detectors that are known to be immune to RFI?
>
> Is "photoelectric" fire detecting technology particularly susceptible?
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