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Re: [TowerTalk] Follow up on AM interference

To: "Tower Talk List" <>
Subject: Re: [TowerTalk] Follow up on AM interference
From: "Jim Brown" <>
Date: Tue, 12 Dec 2006 23:17:55 -0800
List-post: <>
Go to the FCC website on the following link.

Click on the link for AM query, then plug in the lat/lon of your QTH at the 
section near the bottom of the form, with a distance of 15 miles or so. Get 
your coordinates down to seconds for the most accurate data back from the 

You'll get all the licenses, with power, whether they have different 
day/night power and/or patterns, and distance from you. DA means 
directional antenna, DA-N means directional at night, DA2 means directional 
with different patterns day and night. 

Common intermod products are 2A+B, 3A+2B, even A+B and A+B+C. Your 
combination gives 2A+B products at 3820 and 3920, and 3rd harmonics at 3720 
and 4020. These are all carrier frequencies, and they ought to be good to 
fractional Hz if it's a real broadcast station (as opposed to a 

Again, it really helps to listen to the detected audio and compare it to 
your AM radio to nail down exactly which station(s) are in the mix. If it 
isn't coming out of one of their transmitters, you might find some non-
linear detector in your neighborhood detecting and re-radiating it. You 
might be able to take a ham talkie that tunes the frequency of the 
interference (that is, the hamband) and try to find it. The HF receiver in 
my THF6A, for example, defaults to a built-in loopstick for frequencies 
below 10 MHz. 


Jim K9YC

On Tue, 12 Dec 2006 21:01:07 -0800, Tom Osborne wrote:

>HI Gary

>At 4005 and 3993 are the frequencies I noticed tonight.  Also another one 
>around 3800, but the station is either off the air now or they have 
>power 'cause I don't hear it right now.
>Tom W7WHY

>> What frequency are you receiving it on 80 meters?
>> 73
>> Gary  K4FMX
>>> -----Original Message-----
>>> From: [mailto:towertalk-
>>>] On Behalf Of Tom Osborne
>>> Sent: Tuesday, December 12, 2006 9:35 PM
>>> To: Towertalk
>>> Subject: Re: [TowerTalk] Follow up on AM interference
>>> Hi JIm
>>> There is 1 on 1240 and 1 on 1340.  I am about 1 mile from the one on 
>>> and about 5 miles from 1340.  I still think it is something in my 
>>> somewhere because it is nil on the vertical.  73
>>> Tom W7WHY


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