[RFI] A Bizzare EMI Story

[Mike NA6MB]

I vote hammer !

NA6MB



On 11/6/2018 7:30 PM, donovanf at starpower.net wrote:
> From: "Sam Josuweit" <samjos at epix.net>
> To: topband at contesting.com
> Sent: Wednesday, November 7, 2018 2:15:35 AM
> Subject: Topband: Bizzare EMI Story
>
> So after taking a few years off from radio, over the summer I decided to
> rebuild my station and antennas and get back on the air. Was doing fine
> until a few weeks ago, my noise level was S9 on 80 meters. Using a beverage
> it was ok but on my TX antenna it was 120hz hash. I tried everything to
> locate the source, unplugged computers, Directv, DSL modem, freezer you name
> it, checked my entire ground system, it still was there. To make matters
> worse after listening to it on AM I noticed I could hear the local NOAA
> Weather radio station, which is on 162.55 MHZ FM! Now the local transmitter
> for NOAA is on the next mountain over and line of site with my remote QTH,
> but 162MHZ to 3.7MHZ?? This really had me stumped, and I was just about to
> give up. I have an old farm house and don't have too many power outlets, but
> I realized I missed checking the one in our bedroom, and there sits my NOAA
> weather alert radio. Unplugged it and the hash was gone. Since these radios
> monitor constantly for alerts, they must just mute the audio when not in
> use. Apparently something in the radio power supply failed causing the power
> noise, which was then getting modulated by the muted audio. This was
> propagating thru my whole electrical system. I'm just glad I found it.
> Debating if I should take a look at the weather radio or smash it with a
> sledge hammer.
>
> Sam (N3XZ)
>
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-- 
Thanks,
Mike
NA6MB