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[TowerTalk] AM Broadcast Harmonic Interference to 75 Meters

To: Towertalk Reflector <towertalk@contesting.com>
Subject: [TowerTalk] AM Broadcast Harmonic Interference to 75 Meters
From: Byron Tatum <bjtatum1@att.net>
Date: Sat, 5 Dec 2020 16:14:53 +0000 (UTC)
List-post: <mailto:towertalk@contesting.com>
Hello-   Can someone point me in the correct direction, in finding technical 
help and someone to make measurements, regarding a problem I have at my new QTH 
involving harmonic interference from a local AM broadcast station? Here are 
some details - The station is licensed for 5.0 KW daytime / 1.0 KW nighttime 
power levels. The transmitting site is 2.5 miles from my QTH. The transmitting 
antenna is approx 240' of 65G tower on an insulated base with steel guy wires 
broken up with insulators. An old FM broadcast antenna is mounted on top of the 
tower but is not in use I was told. The station broadcasts on 1290 Khz.    My 
problem is an extremely strong harmonic at 3870 Khz both day and night, plus 
there is crud every 10 Khz from about 3600 Khz to 3960 Khz. I have received 
this interference in a very similar manner on my FTDX-5000MP in combination 
with the Micro-Tune RF filter and on a well aligned R-390A. I don't believe it 
is my equipment. I contacted the station owner and he told me that he made 
measurements and is within the FCC limits. I do understand that the station can 
be emitting a signal within FCC limits of harmonics and the harmonics can be 
generated in surrounding objects such as dis-similar metals or corroded joints. 
The crud every 10 Khz indicates to me some serious mixing products being 
generated somewhere.   I feel that I need to find a Ham who has analyzing 
equipment and knowledge of this subject who can come to my place and make 
measurements and guide me onlooking into this.Thanks,Byron W5FH 
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