Hi, Thanks for all the replies. My Microham is a relatively recent unit. I also have a separate power supply for the MicroHam.
Is having the Microham directly on top of the KAT500 Tuner with the microphone cable almost touching the RF out a potential issue? If so, this might be an easy fix for now. Thanks On 3/11/14, "Joe Subich, W4TV" <li...@subich.com> wrote: > > VSWR is not an issue - the issue is imbalance in the antenna system. > The problem is well known as the "common mode RFI" issue due to a lack > of effective decoupling of the antenna and feedline. > > A *much more common* issue is users who fail to follow instructions and > connect microKEYER II (or any other accessory that handles microphone > audio) to the same power supply as the transceiver. With "modern" rigs > which use 12V finals, the peak power supply current can be greater than > 25 amps. When the transceiver uses light cable for power (anything > less than #10 wire) and "friction" connectors like Molex or Power Pole, > the voltage drop in the power supply return can be significant. That > drop causes some current to flow through the accessory and "pump" the > ground reference to the accessory. With just 0.2 Ohms in the connector > and ground return, that means at least 0.5V *in series* with the audio > input! > > If you are using any device that handles microphone audio, either power > it from the K3's +12V accessory jack or use a *separate* isolated power > supply. > > 73, > > ... Joe, W4TV > > > On 3/11/2014 5:58 PM, tom...@videotron.ca wrote: > >Ok, thanks, that's what I thought. A little more complicated since I have a > >MicroHam microkeyer II in the circuit but probably fixable. > > > >73's Tom > > > >On 3/11/14, "donehrl...@q.com" <donehrl...@q.com> wrote: > >>Almost certainly RF getting into the mic circuit. Try a different mic .. or > >>use the rear panel mic connector as a check. You probably have high SWR > >>into the antenna feedline (or coax) after the tuner on 20 meters and that > >>is why you only see problem on 20M. High SWR on the feedline (Note: your > >>rig can be seeing low swr .. it is AFTER the tuner where you have high SWR) > >>results in high current or high voltage that then couples into other shack > >>wiring. Of course, the higher power from the KPA500 pushes those > >>voltages/currents to levels that are more likely to cause problems. Been > >>there, done that .. many times. > >> > >>Don K7FJ > >> > >> > >>>Ok, > >>> > >>>So my audio is quite distorted as I can hear in my headphones with the > >>>monitor. But this only happens on 20m and only with the KPA500 in operate. > >>>Sound like RF? or is something else going on? > >>> > >>> > >>>Thanks > >>>______________________________________________________________ > >>>Elecraft mailing list > >>>Home: http://mailman.qth.net/mailman/listinfo/elecraft > >>>Help: http://mailman.qth.net/mmfaq.htm > >>>Post: mailto:Elecraft@mailman.qth.net <Elecraft@mailman.qth.net> > >>><Elecraft@mailman.qth.net> > >>> > >>>This list hosted by: http://www.qsl.net > >>>Please help support this email list: http://www.qsl.net/donate.html > >>> > >> > >>______________________________________________________________ > >>Elecraft mailing list > >>Home: http://mailman.qth.net/mailman/listinfo/elecraft > >>Help: http://mailman.qth.net/mmfaq.htm > >>Post: mailto:Elecraft@mailman.qth.net <Elecraft@mailman.qth.net> > >><Elecraft@mailman.qth.net> > >> > >>This list hosted by: http://www.qsl.net > >>Please help support this email list: http://www.qsl.net/donate.html > >> > >> > >______________________________________________________________ > >Elecraft mailing list > >Home: http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/mmfaq.htm > >Post: mailto:Elecraft@mailman.qth.net <Elecraft@mailman.qth.net> > > > >This list hosted by: http://www.qsl.net > >Please help support this email list: http://www.qsl.net/donate.html > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net <Elecraft@mailman.qth.net> > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > ______________________________________________________________ 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
