Ron,
Since the quotation was from my posting, I'll answer the question.
First, in most cases these days, merely opening up the housing of the
detector is likely to void the warranty. (Replacing the battery usually
does not require opening up the entire unit.) Next, keep in mind that this
is both a heat and smoke detector. There must be airflow for the smoke and
the IR sensor must be able to see the surrounding area to detect actual
fire (flame).
Thus, adding a shield to the interior of such a unit is not trivial. I
imagine that it can be done, but I do not suggest that as a common
approach. Any shielding should have been part of the design from the
get-go. In any case, a shield must allow for air flow, must not obstruct
the IR detector view, and must not short out any circuitry. Oh yeah - to
be effective, that shield should be grounded unless it forms a true Farady
cage around the entire unit's electronics (not likely). An ungrounded
partial shield will become just another re-radiating antenna within the
unit.
I hope this answers the question. Thanks for asking.
73,
Dale Svetanoff, WA9ENA
Sr EMC Engineer
E-N-A Systems, LLC
Specializing in shielding applications, system grounding, and lightning
protection
> [Original Message]
> From: roncasa <roncasa@verizon.net>
> To: RFI List <rfi@contesting.com>
> Date: 11/6/2012 7:00:15
> Subject: Re: [RFI] RFI to new photoelectric smoke detector
>
> On 11/05/2012 11:44 PM, Kelly Johnson wrote:
> >> 3. Install internal shielding in the detectors (which will probably
void
> >> the warranty and may result in non-operation - not a recommended
approach)
> >>
> >>
>
> Why?
>
> There is a small opening to detect smoke. Simply shielding the remaining
> unit certainly doesn't void
> any "warranty". It may or may not be the solution but certainly a try.
>
> I never heard of this. Usually a chirp is indicative of weak battery,
> not RF related.
>
> Ron, wb1hga
>
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