[RFI] ADT security system noisy?

[myles l]

i had some trouble w/a older unit,  specifically it was the battery charger ckt. wouldn’t be surprised if  something in there was ‘off’



> On Feb 16, 2026, at 3:49 PM, David Eckhardt <davearea51a at gmail.com> wrote:
> 
> I'm sure there is lots of digital circuitry within the box.  Digital
> circuitry = RFI ! ! !  I'd suggest temporily disconnecting the battery.
> Let ADT know before you do so or they may interpret that as in ingress.
> Also disconnect their dable, if any.  I'll be with those two actions, the
> RFI will cease.
> 
> Have you "sniffed" the ADT box and installation with a spectrum analyzer
> and a small (maybe 5-cm in diameter or so) loop?
> 
> Dave - WØLEV
> 
> On Mon, Feb 16, 2026 at 8:26 PM Joseph Bouchard <joek1vw at gmail.com> wrote:
> 
>> Hi,
>> 
>> We have a club station at a museum and are chasing down RFI (KB1BSM).  I
>> threw every breaker in the building with someone watching the panadapter.
>> It didn’t kill the particular noise we are chasing, which shows an S9
>> harmonic about every 34khz on 20m.
>> 
>> Then someone said “we have an ADT security system with its own battery
>> backup.” They think they can call ADT and get them to remotely shut it down
>> temporarily for a test, but I’m a little skeptical… if they are talking to
>> it remotely, it’s not really dead is it? I tried to get a model number but
>> all I see is a red metal lock box with a little ground plane antenna, about
>> 6” tall.  I suspect it’s a cellphone antenna.  I don’t expect that UHF
>> radio is causing us problems on HF, but the system of sensor could be noisy.
>> 
>> Anyway, my question for the group, are ADT security systems a known
>> culprit for RFI?
>> 
>> Thank you,
>> Joe K1VW
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> 
> 
> -- 
> 
> *Dave - WØLEV*
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