I so wish the local grow lights worked that way... :)
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 12/25/22 16:17, Hare, Ed, W1RFI wrote:
24.998 MHz would have done just as well. 🙂
I have a funny story about that sort of thing. A few years back, I was
doing a lot of HF mobile work on CW. One day, I went way to the back of
a parking lot to operate. The lot was almost empty. A car pulled and
parked right next me with the car audio system blasting away, loud, with
the bass buzzing like most of them do. I mean, he had a whole flippin'
parking lot, and he had to park right next to me.
100W CW, 14 MHz: CQ CQ CQ DE W1RFI/M W1RFI/M CQ CQ CQ DE W1RFI/M K
I happened to look over and he was fiddling with the controls of his
sound system. When I stopped, he stopped. I let him be for a minute and
sent a single dit. He jumped a bit. Aha!
I then just sent my call, and he reached for the sound system, then
stopped when I did.
I started sending a string of dits and watched him fiddle, then stopped,
then sent dits then stopped.
Finally, he looked over at my car with the big antenna and saw my
pie-eatin' grin, gave me a really dirty look and drove away.
Now, if had been playing Metallica, I wouldn't have minded, but rap
ain't music at any volume.
There's another couple of related "immunity" stories. I was doing BPL
testing in Ohio with a very cooperative BPL operator. We were measuring
radiated emissions, but also looking as susceptibility. The emissions
were horrible, right at the limits because he had warned the company
that he didn't want any trouble from "Ed." (I didn't have a last name in
that industry. I decided to fire up a transmitter, 100W to a mobile
whip on various bands. What I found was that if I did a brief
transmission, the system stopped, then quickly resumed normal
operation. But if I transmitted for more than 20 seconds, the system
did a hard stop and the modems on each end of a leg had to reconnect
with each other. So, 21 seconds of carrier and the band was pretty
quiet, except for bit of light clicking. Then, after about 30 seconds,
I could hear modem negotiation sounds, then after about 3 minutes, data
started flowing again. We found that SSB or CW slowed it down, but
didn't take it down. There was enough data getting through that the
system didn't think it had lost communication and reboot itself.
So, that afternoon, the BPL operator joined us. We were running around
and he was showing us how he could monitor data rates over WiFi from a
laptop in the back seat. We were on a part of the system operating on
the 50 MHz band, so I switched the transceiver to 50 MHz CW and a
6-meter antenna. When he heard how loud the noise was, about S9+10 dB,
he said he understood why they should not use the ham bands. As we were
talking, I casually reached over and keyed the transmitter with 5 watts
He was in the back seat and he asked, "Hey. where did it go?" I told
him that I had just transmitted on 6 meters with low power. Let's just
say his expression was colorful and very holy. I then told him that if I
transmitted for 21 seconds, his system would be down for about 3 to 5
minutes. He asked me to demonstrate. I did, and it did just what I had
seen at other parts of his system.
He ultimately did resolve all of the interference problems by careful
choice of frequency, but he was plagued with intemittencies all along as
various VHF operation took the system down.
Now, this one has a followup. FPL in Florida set up a BPL trial area.
A ham was squarely in the trial area, so he contacted me and asked what
he should do. He had about S9 noise across several bands. I told him
how and why he should complain, but I also told him the story that had
happened in Ohio. I went on to explain that if he operated SSB or CW,
he'd slow the system down, but that FM or digital operation would take
it down hard. He wasn't a CW op, but he said that he was very
interested in learning digital operation. So, he set up a 10-minute brag
tape and get himself all set up to do PSK-31. PSK-31 was robust enough
that he was able to make contacts, and he said that he was having so
much fun that he operated for hours nearly every night.
Several months later, they shut down the trial. He talked iwth the
engineer who was in charge of the system, who told him that the system
just wasn't reliable, because it would stop working for hours on end in
the evening when everybody was home using it.
And that's another story that never made it to the pages of QST! I got
37 years worth of them! LOL!
Ed, W1RFI
------------------------------------------------------------------------
*From:* RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of
Dave (NK7Z) <dave@nk7z.net>
*Sent:* Sunday, December 25, 2022 6:48 PM
*To:* rfi@contesting.com <rfi@contesting.com>
*Subject:* Re: [RFI] : Solar Panerl RFI / noise in sync with music
Did you by chance transmit on that frequency, while the thing was on? :)
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net <https://www.nk7z.net>
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 12/25/22 12:09, Henry Pfizenmayer via RFI wrote:
Mike et al ---If that was not tongue in cheek as they say -- this last summer
I started getting thumps of
noise on 6 meters -and was far worse at 25 mhz -- Then I noticed it was in
sync with neighbors outside
speakers thumping out a strong bass line. I went out with my IcomR10 rx
and loop -
and yep that was the source. The amp was obviously going into oscillation in
sync with the loud bass notes .
No use talking to that guy - so I just prayed the damn amp would fry itself .
Prayers were answered
in just a hour or so and noise never re-appeared.
73 Hank K7HP
Message: 1
Date: Sun, 25 Dec 2022 11:51:20 -0500
From: Michael Martin <mike@rfiservices.com>
To: "Dave (NK7Z)" <dave@nk7z.net>
Cc: Rfi List <rfi@contesting.com>
Subject: Re: [RFI] Another Solar Panel RFI System
Message-ID:
<CAPZkRSEvyTNyLcJT-3e1gNnkTP+WNX15DFXUXHpqf5YZa67YEw@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
I'm trying to capture a noise with the intermittency rhythm in sync with
Christmas music
Michael Martin
RFI Services
51 W Bay Front Rd
Lothian, MD 20711
240-508-3760
mike@rfiservices.com
www.rfiservices.com<https://webmail.centurylink.net/app/www.rfiservices.com
<https://webmail.centurylink.net/app/www.rfiservices.com>>
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