On 2/3/2012 12:43 PM, Guy Olinger K2AV wrote: > This is an endemic "uncurable" problem.
Maybe not. One mechanism I suspect, based on the symptom that it happens with the Line Input turned up, is magnetic coupling into the unshielded audio transformer on the Line Input. That coupling is nearly always pure 60 Hz, without harmonics, and is a well known problem.. In data modes, the Line Input is rolled off sharply at some frequency like 200 Hz or so, which knocks the hum down by something like 18dB.. I recommend doing that for SSB too, because the lower octaves carry no intelligibility but can waste a lot of TX power. The separation that matters this this case is the generator of the magnetic field, usually the power transformer for a big power amp, but it can also be caused by wiring errors in the power wiring in a home. It can help a lot to rotate the amp to put its field at right angles to the magnetic receiver (the audio transformer in the K3), and also to move it further away from the K3. As to RFI with lines running past a computer -- I had that issue in Chicago, where I used a long wire antenna on 80 and 160, and it locked up the serial connection. The culprit there was the K2 serial cable, which used PARALLEL wires inside a shield. I replaced it with TWISTED PAIRS without a shield, with one pair for each circuit used between the computer and the rig, with the return for each pair going to the chassis on each end, and the problem went away. With the original cable, it locked up at 12 watts. With the twisted pair, I could run full power from my Titan 425. 73, Jim 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
