That is a VERY important point Joe. "getting mixed somehow"- often occurs without fault from either of the two mixed stations - but as a result of a nearby rectification area (the right metal hardware (rectifiers) coupled to a antenna of some sort with good primary RF energy from the stations) - that maybe located many miles from both stations - but "breeds" the mix. And that is what you hear on 160 and 80.
Guys are fast to blame the AM radio stations (and "some" have problems) - when after a deeper dive - the stations spectral purity meets or exceeds the FCC regulations. I have found my share of AM station "mixers" - and it is not easy - they take on a non powered life of their own - just like the first crystal radio I built with a razor blade and pencil lead. My most recent mix at K3LR involved 3 AM stations. The closest one 1470 - had their 2nd harmonic added to the next stations primary frequency - result was booming signal (both audios) on 3.730 MHz. The 1470 2nd harmonic with the further station added together gave a - signal on 3.510 (both audios). Lots of DF to find the "mixer". Which was one bad power pole ground (located close to station #1) was the problem. Ground fixed - everybody is happy. problems gone. 73, Tim K3LR -----Original Message----- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Joe Giacobello, K2XX Sent: Thursday, December 22, 2011 10:26 AM To: rich...@karlquist.com Cc: topband@contesting.com; lrp...@comcast.net Subject: Re: Topband: 1820 BCB At this point, I'm convinced that the source of the problem is the 24 hour station and that the WPIN and WGFC signals are getting mixed somehow to produce the AM signal on 1840. 73, Joe K2XX _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK