Odd Reception and FCC Research

tweiss3

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Apr 24, 2020
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If this isn't the proper subforum for this, I apologize in advance.

Our club does a band exploration net (rotates 6M thru 80M) after our normal net on the repeater. In discussion during the next, one club member (about 1/4 mile from me) was talking about some filters he was working on for some interference he was experiencing on 160M. I don't have an antenna for 160, but I had noticed an anomoly on 80M that I asked him about, but he seemed stumped, though mentioned it might be a harmonic of some type.

At 3.850 MHz, I hear a broadcast radio, advertisements an all. Now, looking up possible harmonics, the third harmonic is 1283kHZ, which aligns with WONW AM radio station in Defiance, Ohio. My QTH is EN91, about 150 miles as the crow flies from this 1kW broadcast location. Is this normal to pick up this AM harmonic when in LSB? At this distance? I would think an AM signal would sound distorted, and this is pretty clear, almost like a weak signal AM station in the car.

Secondly, I was trying to do some research to determine if there was something else nearby that could be causing this, and any other interference. There are a large number of tower structures that I know about, but I'm not sure what they are for. I am able to lookup the tower registration, but how does one find out what is licensed to transmit from that location? Frequency, use, RF type, etc?

Thanks!
 

spacellamaman

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Aug 22, 2014
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municipality of great state of insanity
yeah that gets kinda involved. i'd love to hear a simple way of doing things too. just something to think about, regarding mystery signals etc there is a cell tower owned by american tower company or something like that near where i live. its part of the fort bragg trs and about 80 miles west of the base. it was years before i put all that together. even the best records don't always contain everything.
 

tweiss3

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Ohio
I checked antennasearch and it didn't give any more information than I already had from the ASR database.

Is 150 miles too far to be receiving a 3rd harmonic interference? Should I be looking elsewhere?
 

tweiss3

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Ohio
So, my club mate did more searching today, and his findings can be summed up as the following:

"I believe that the second harmonic (2.7 MHz) of WARF 1350 KHz is mixing
with the fundamental frequency of WCUE (1150 KHz) producing a summed
carried of 3.85 MHz (2.7MHz + 1.15 MHz). On 1550 KHz I think I can hear
the difference signal (2.7MHz - 1.15MHz), but there is another signal in
there also (perhaps the Delaware, Oh. AM station at 1550 KHz). "

So basically, we are dead between the two antenna arrays (split almost perfectly less than half a mile both directions). This is a very odd phenomenon. I'm glad he has more knowledge than I do. Also, I think the third station is still 1280 WONW.

Just incase anyone is wondering, or it could help someone else with similar problems in the future.
 

prcguy

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Jun 30, 2006
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So Cal - Richardson, TX - Tewksbury, MA
I think 150mi is really far to be picking up any sort of harmonics. You should be able to go online and hear a live KONW feed then compare with what your hearing on 3.850 to see if its actually that station or do the same for some other nearby stations. Stations with towers close to each other can create IMD with sum and difference frequencies but that would be weak and should not travel far.
 
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