Re: [Elecraft] Anyone near an FM station on ~97.1
On 7/24/2018 9:17 AM, j...@kk9a.com wrote: When I lived near Chicago I heard a mixture of two AM broadcast on 80m using a 160' high rotating dipole. I first experienced this in 1953 (before I was licensed) with stations near me on 930 kHz and 1470 kHz mixed on 3870 (I think). This is nothing more than passive intermod, and can occur virtually anywhere, including in one of the transmitters! I also experienced it intermittently when I lived on the northside of Chicago three miles N of Wrigley Field, and the mixes were of 50kW stations with TX locations 20 miles W of me. I even heard WBBM's second harmonic (on 1560 kHz)! 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Anyone near an FM station on ~97.1
When I lived near Chicago I heard a mixture of two AM broadcast on 80m using a 160' high rotating dipole. I assumed that something was rectifying but I never found the solution. I am curious if you are received this interference while using bandpass filters. John KK9A Mike Wetzel W9RE wrote: I have had an interference problem on the top part of 15 meters (21380 to 21450) from an FM station 1 mile from my house whose frequency is 97.1Mhz. It peaks about S6 and is quite noticeable with only coax connected and no antenna selected. I have (2) -K3 and it is present on both. I installed new synth boards in one but the interference is still there. It sounds like a very broad FM signal. I had the station engineer do a spectrum search and he found no issues. I do not find this interference on an Icom radio. Has anyone else experienced this and if so have you found any solutions? I did a check of just the K3 (a year or so ago) on battery power and no other connections and it was still present although much weaker. Thanks, Mike W9RE __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Anyone near an FM station on ~97.1
Hi, Let's do the math. The K3(S) has an IF frequency of 8.215MHz. So when you listen to, say, 21.4, the synth is generating 21.4 + 8.215 = 29.62MHz. Multiply this by 3 and add the 8.25.MHz and you get 97.06MHz! The K3's mixer has a *very* strong response to the 3rd harmonic of the LO since it is essentially a square wave. The responsibility for removing this spur is entirely with the HF filter which evidently does not have enough suppression to totally reject this extremely strong signal. Do you have the tuner in the K3? Turning it on would probably help since it is low pass in nature. An external auto tuner should also help. Your ICOM radio probably is an up conversion radio so would not have this particular problem (responding to odd harmonics of the LO). AB2TC - Knut W9RE wrote > I have had an interference problem on the top part of 15 meters (21380 to > 21450) from an FM station 1 mile from my house whose frequency is 97.1Mhz. > It peaks about S6 and is quite noticeable with only coax connected and no > antenna selected. I have (2) -K3 and it is present on both. I installed > new synth boards in one but the interference is still there. It sounds > like > a very broad FM signal. I had the station engineer do a spectrum search > and > he found no issues. I do not find this interference on an Icom radio. > > > > Has anyone else experienced this and if so have you found any solutions? > I > did a check of just the K3 (a year or so ago) on battery power and no > other > connections and it was still present although much weaker. > > > > Thanks, > > > > Mike W9RE > > > -- Sent from: http://elecraft.365791.n2.nabble.com/ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Anyone near an FM station on ~97.1
I have had an interference problem on the top part of 15 meters (21380 to 21450) from an FM station 1 mile from my house whose frequency is 97.1Mhz. It peaks about S6 and is quite noticeable with only coax connected and no antenna selected. I have (2) -K3 and it is present on both. I installed new synth boards in one but the interference is still there. It sounds like a very broad FM signal. I had the station engineer do a spectrum search and he found no issues. I do not find this interference on an Icom radio. Has anyone else experienced this and if so have you found any solutions? I did a check of just the K3 (a year or so ago) on battery power and no other connections and it was still present although much weaker. Thanks, Mike W9RE __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
