Of course if one does not wish to perform surgery on the K3, it would be possible to set up a 3-dimensional Helmholtz coil around the K3 fed with 50 or 60 Hz line voltage and adjust the X, Y and Z Helmholtz drive (level and phase) to null the ambient field at the offending transformer(s).
Jack Jim Brown wrote: > On Tue, 07 Jul 2009 13:13:57 -0400, Jack Smith wrote: > > >> Another alternative is to replace the transformers with shielded >> versions, assuming space on the PCB is available and a shielded >> transformer with the same electrical specifications and footprint >> > is > >> available. >> > > Or simply eliminate the transformers. They are totally un-necessary > if you do the simple chassis bonding shown in my Ham Interfacing > tutorial. > > http://audiosystemsgroup.com/HamInterfacing.pdf > > More stuff, in words, in > > http://audiosystemsgroup.com/RFI-Ham.pdf > > See the chapter on Solving Problems In The Shack. > > Another thing to try before digging into the rig. If Elecraft has > followed my recommendation and made TXEQ work on the LineIn, you can > Use TXEQ with maximum cut on the two lower frequency bands. This is > good engineering practice to maximize communications audio quality > anyway, and it should suppress 50/60 Hz by about 20 dB (15dB for the > lowest filter, plus a few more dB from the skirt of the next highest > filter). > > This problem with magnetic field susceptibility is well known. My > neighbor, K6XX (who as it happens also works part time as an > engineer for Elecraft) has so much magnetic coupling to his K3 from > a big power supply that it regenerated to 500W when he tried using > the LineIn for RTTY. > > 73, > > Jim Brown K9YC > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
