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
