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AM broadcast on 80 meters?

Oct 12th 2017, 09:18


Joined: Apr 7th 2012, 19:22
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Total Posts: 0
On a 80 meter frequency used by one of our ARES net, I am hearing an AM signal that sounds like a broadcast station. Can interference from AM MW reach that high, and would a high-pass filter with cut-off of 1700 Hz help? Thanks.
Oct 12th 2017, 14:44


Joined: Apr 4th 1998, 00:00
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Total Posts: 0
Yes sometimes the filter can help. But, Rigs like the K3 with ham band bandpass filters are much less likely to have difficulty with a clean transmitter than receivers that use the same filters for ham band and general coverage reception.

Perhaps the first thing to do is to take out any preamplifiers and put in some front end attenuation to see if that helps--it could just be a preamp or front end mixer overloading.

One clue is to whether everyone is hearing the interference--it is possible, though rare, to have a misadjusted broadcast transmitter.

Zack Lau W1VT
ARRL Senior Lab Engieer
Dec 23rd 2017, 13:36


Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
It never hurts to contact the broadcast station engineer and talk about the problem you are experiencing. You might find them to be fellow hams. You could even ask if they can tell you the level of the appropriate harmonic.of the carrier frequency from their last POP or inspection.

Here in Cleveland, OH a few years back some hams had recurring issues with a 10 kW station on 1300 kHz. The 3rd harminic became much stronger during or after a hard rain. The ham stations were less than two miles from the AM station's antenna, in the near RF field.. It turned out the station itself was clean. The IM seems to be generated in dissimilar metal junctions all along the telephone and cable TV cabling running throughout the residential neighborhood. No easy fix!

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