[RFI] RFI to new photoelectric smoke detector

[Kelly Johnson]

I tried multiple bands and multiple beam headings today, in addition
to trying 80m.  I couldn't make the smoke detector "chirp" today.  I
have no idea why.  I assume it won't happen again until the next
contest :-)


On Mon, Nov 5, 2012 at 7:45 AM, Dale Svetanoff <svetanoff at earthlink.net> wrote:
> 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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>
>