Hello All:
For many years I?ve had horrible RFI buzz in all AM radios in the house.
The noise is also S9 on all of my HF receivers on 80/75 meters and about s5
on 40 meters. Higher HF freqs are noisy but not nearly as bad. VHF/UHF
seem fine.
The power co. said not them. I tried shutting down main power breaker for
the house. The noise pattern ?changed? but still there. I?ve verified that
the computers in my house, though indeed noisy, are not the main culprits.
I think I?ve determined that its coming from my home alarm system. It has a
battery backup which would explain why the noise is still there even with
main power in the house shut down. When the AC power is shut off, the alarm
keypad starts blinking all of the indicator lights by design. When that
scenario happens, the RFI changes from a rapid pulsing noise to a much more
noticeable pulsing ? and guess what - the pulses occur in perfect
synchronization with the blinking indicator lights on the keypad.
So here?s the question:
How do I tackle this? I?ve had the alarm co. here and they insist it?s not
the alarm system. I?m pretty sure it is. Unfortunately there are control
wires running throughout the house to the various sensors and switches, from
the attic down to the basement. It could be the main control box, which
contains the actual digital circuitry. It could be one of the keypads
either by poor design or an actual defect. Either way , the noise is
present all over the house, so clearly the wiring is radiating the RFI. In
terms of HF, it pretty much obliterates 75meters. Broadcast AM radios are
okay tuned to a strong station.
Anyone have any experience with this sort of problem?
Thanks in advance,
Marc, WB2JUF
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