On 8/26/2017 10:58 AM, Lynn W. Taylor, WB6UUT wrote:
First, he's reporting that his CW signal interferes with his TV, not the other way around. It's not the VHDSL (probably) signal getting out, but his 40 meter signal getting in.
Doesn't matter -- thanks to the principle of reciprocity, any passive system that radiates will also receive, and all of that interface (wiring, transformers, cable termination, Pin One Problem) is passive. Take my post and substitute the word "receive" for "radiate." Reciprocity is the principle that causes antenna gain and directivity to be the same on receive as on transmit.
Further, electronics at both ends of these systems are noise sources, and both are susceptible to interference, and both input and output stages can be susceptible to interference. RFI often comes into audio power amplifiers on their loudspeaker wiring, which couples back to the input of the stage via the feedback network, where it is detected and amplified.
Pin One Problems inject any current on cable shields onto the signal common bus (traditionally called "ground"), where it gets injected into gain stages at the whim of the PC layout artist, detected, and amplified (or breaking up the digital signal). Study the tutorial material on my website. Neil Muncy, ex-W3WJE (SK) published work documenting this in 1994. In bar conversation, he observed that most RFI issues are caused by Pin One Problems. In 2003, I published research showing that statement to be entirely correct with respect to audio gear. Those AES Papers are on my website. There's also tutorial material that's easy to read.
Because Pin One Problems are putting the interfering signal onto the signal return bus (signal ground), there's no logic between which gain stage detects it and the cable it came in on. The RF could be on an output cable, or on the cable for input #3, but turning the gain for the input or for mic #10 could cause the RFI to increase in level.
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 Message delivered to [email protected]
