On Tue, 10 Nov 2009 10:29:39 -0400, robby robertson wrote: >I thought my microKEYER was guilty of RFI but it turned out that the audio >patch cables for line in and line out had a less than 10% shield. I >temporarily solved the problem with ferrite but a more permenant solution >will be RG-58au.
Your assessment of the problem is wrong. The problem is NOT shielding of the cable, it is either a pin 1 problem in the equipment one end or the other of that cable or RESISTANCE in the cable shield. There are two possible fixes for a pin 1 problem, one of which you found. The other fix is to rewire the defective equipment to eliminate the pin 1 problem. Both pin 1 problems and shield resistance couple shield CURRENT into equipment. A ferrite reduces RF shield current. If it's resistance, RG58 with a robust copper braid shield will help because it has less resistance, not because it's better shielded. If it's a pin 1 problem, it won't help. Another point. That cable is acting as a receive antenna. Changing the length (or orientation) of ANY antenna can change its behavior. For a tutorial on all of this see http://audiosystemsgroup.com/RFI-Ham.pdf 73, Jim Brown K9YC ______________________________________________________________ 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