In the creeping features department, a similar high-pass filter (60Hz, 120Hz, 300Hz?) might be nice for PSK31 and other digimode hams who use panoramic display software since they don't transmit at a fixed offset. Leigh/WA5ZNU
wayne burdick wrote: > > The K3 has a CONFIG menu entry called "AFSK TX". If you set it to "FIL > ON", a 400-Hz transmit-mode audio filter is inserted, centered around > the mark/space tones. This is only available when the rig is set for > AFSK A mode. It should be effective against low-frequency hum coming > in through the mic or LINE IN connectors. > > 73, > Wayne > N6KR > > > On Sep 28, 2009, at 2:45 PM, Leigh L. Klotz, Jr. WA5ZNU wrote: > >> Jim K9YC wrote: >>> Magnetic field coupling from the power supply to the K3's input >>> circuitry, >>> probably due to the use of unshielded audio transformers in the K3. >>> This >>> is a well known problem. One good band-aid is to go to the TXEQ1 >>> settings and fully cut the three lowest octave bands. >>> ... >>> One of my neighbors had so much magnetically coupled hum >>> into the Line In transformer that it regenerated to full >>> output power when he tried to run RTTY in AFSK mode. >> >> Note that the upcoming firmware upgrade will reportedly eliminate >> TXEQ in >> AFSK (and other audio-based digital modes), and it apparently may be >> some >> time before another update provides true per-mode TX/RX EQ. So people >> with hum will need another solution, except for the voice modes. >> >> I tried wrapping the component side of the transformers in a sheet of >> Mu-metal (actually, a competitor, not Mu-brand) and noted no >> difference. >> It was probably a futile effort anyway as it didn't wholly enclose the >> transformer; probably I need to complain to Maxwell about this. >> >> Leigh/WA5ZNU > > ______________________________________________________________ > 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 > > -- View this message in context: http://n2.nabble.com/K3-hum-problem-not-the-usual-tp3730769p3737184.html Sent from the [K3] mailing list archive at 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
