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Just finished my 40m and had a first QSO. YEA! BUT, why is there always a BUT?? I'm hearing a nearby AM station (.25 mile) at 1540 khz in the background. Luckily it's a daylight broadcaster. Antenna is a 31 foot non-resonant wire vertical with 40 buried radials fed with low loss coax, a unun at the feed. I have an I.C.E. Broadcast filter at my station that doesn't seem to make a difference. Any ideas?

Sounds like it could be 2nd harmonic from the AM station? These days many AM stations don't get enough attention or care on the engineering side of the balance sheet. Does the station show up on other radios with or without the broadcast filter attached. In other words, is the interference present only on the QCX?

Contacting station personnel about the interference might be the biggest challenge or opportunity! Good luck resolving the issue!

--Al

2nd harmonic would be on 3080 4th harmonic would be on 6160 and 5th on 7700 normally it is the odd harmonics that are much stronger, so my guess is it is not a harmonic (could be some other mixer product).

Have you the QCX in a metallic box ?
If you disconnect the antenna is the AM station still there?

Jan

I live in harmony with a 22kW AM station, but it's 3km away, not a mere .25 miles!

A couple of things:
1)? I see a model; 402X ICE BCB filter - it has a ground lug.? Have you attached a ground at that point?
2)? I'd try an attenuator in the antenna line, just to see if the QCX receiver is being over-loaded.? Sometimes,
just a few dB of attenuation will make the problem go away.
3)? Have you other rigs/antennas that manage to survive the onslaught of a BC station that close?
4)? I use an L-network with the inductor as the shunt element - this allegedly provides a high-pass response.
???? Do you use an antenna coupler of any kind (including internal couplers on other rigs)?
5)? It might be a common-mode issue - have you tried a balun or some kind of choke right at the rig?
???? Like a dozen turns of RG-174 around a type 43 core?
???? If it was common-mode, I can envision a case where the RF would flow around your filter.

Good luck
Jerry
KI4IO

They are listed at 50K, but not sure it's that high according to a search on the station. Think they may actually be going off air and selling the transmitter site for developement. Last community group meeting mentioned something about that area, and I'm gathering more info. My other HF rigs not as bad with the BC interference. My FT990 has some issues with FM though, some images sporadically throughout the HF range. I live near a very large antenna farm,the proverbial Radio Hill, where most of the FM and TV broadcasters have teir towers.?

Yes the interference goes away. Looking to eventually case it up, I do have a tin that it fits in, just need to figure a way not to butcher it up. It would make a nice companion to my PFR3 for park portable.

Thanks Jerry,

All great ideas. I will try them.

I tend not to ground the filter since I don't always have it in line, I sometimes MW dx. Shack is on the second floor, though I do have a ground line down to the yard. So far I've made solid QSOs in spite of the interference, since most of us hard core CW guys have the built-in filter between our ears, hi.

73

Jerry N3HAM