Hello Mike,
Yes, I had a similar problem. I have a monopole cell tower about a quarter
mile to my SE. It has been there for 20 years and produced no RFI. About a
year and a half ago, it started to produce RFI whenever the night (red)
lighting system was active, about one second on, two seconds off. The noise
was about S-8 on 28MHz when I was pointed to the SE (my normal noise floor
is about S-1 to S-2). The noise produced was a buzz whenever the red light
was visibly producing light. The daytime white strobe on the tower produced
no noise.
I looked up the tower owner in the FCC database and sent them an email.
They responded that they will look into it. A couple of weeks later, I
followed up and asked for status. They responded everything seemed OK.
I asked if they could provide me the manufacturer name of the lighting
systems so I could contact them and discuss the RFI problem, which they did.
I was in the process of collecting some additional data on other towers in
the area, and the noise at my nearby tower stopped and has not returned in
over a year. I can only assume they found the issue. I suspect it was a
defective power supply. The lighting systems can take a beating from
lightning. One would think the noise produced by lighting systems would be
detrimental to receive systems on the towers but perhaps the cell companies
don't monitor that as closely as us hams do.
Jeff, W4DD
-----Original Message-----
From: RFI <rfi-bounces+w4dd09=gmail.com@contesting.com> On Behalf Of
k9mk@flash.net
Sent: Wednesday, May 25, 2022 12:01 PM
To: rfi@contesting.com
Subject: [RFI] Repeater Desense from Tower Light? Or what is it??
Greetings to the group,
Last night I was monitoring our county skywarn net on 2M as storms went
through our area. On a number of the marginal stations, the ones that were
in that 'almost full quieting' signal level into the repeater I observed
what I thought was a desense hit. That meaning where the signal went from
almost full quieting to a bit noisy (> 20 dB quieting). It would toggle up
and down and then I realized that the so called desense had a cadence.
About one second on and then maybe 2 seconds, or something like that. I
quickly realized it the was tower light. Has anyone seen this or maybe
dealt with something like this? The light and antennas are at 400', and the
repeater is in the bunker at the tower base. Thanks in advance.
73 Mike K9MK
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