Topband: AM broadcast multiplexing

[Frank W3LPL]

Phil,

You can use a simple direction finding antenna to locate the source
of the spurious signals

See March 2021 QST

It works very, very well

73
Frank
W3LPL



----- Original Message -----
From: "Phil Lefever via Topband" <topband at contesting.com>
Cc: "Topband" <topband at contesting.com>
Sent: Friday, April 21, 2023 5:59:50 PM
Subject: Re: Topband: AM broadcast multiplexing

Eric,

I mentioned in my post that I have a filter inline. I have tried a number of different configurations, different receivers, filters and attenuators. I can see the signals on my spectrum analyzer with the BCB filter and a healthy amount of attenuation also.

The spurs exist at my antenna(s). Of course there is question as to where they are created, at the radio transmitter site, or my neighbors chain link fence...

Was simply sharing another instance of AM multiplexing that has caused issues.

73

Phil, KB0NES


On Friday, April 21, 2023 at 11:56:25 AM CDT, Eric Scace K3NA <eric at k3na.org> wrote: 


Being so close to the transmitter site. it's quite possible that you are experiencing receiver front end overload, and your receiver is generating some of these signals.

You might wish to try the AM “brickwall” filter. DX Engineering sells them for $195. I have used one in many measurement situations at locations even closer than yours — it’s quite effective in knocking down AM broadcast signals to a level that eliminates receiver overload and internal IMD product generation.

— Eric K3NA
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