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
