On 10/20/2011 6:21 PM, [email protected] wrote: > I apparently have a bigger problem with RF in the shack and it has > nothing to do with the loop.
Hi Don, Your email, and some of the solutions offered, reflect some common misconceptions about RFI, including an earth connection as a solution (it is NOT), and SWR as a cause (it is NOT). The usefulness of noting changes from the original SWR values is that it tells you SOMETHING HAS CHANGED in the antenna, so that you know to go looking for something that is broken. I strongly suggest that you download and study my tutorial on RFI for Hams. Nearly all problems blamed on "RF in the shack" are really caused by Pin One Problems in equipment where the RF is detected, and by antenna systems that put RF on the outside of the coax. Study http://audiosystemsgroup.com/RFI-Ham.pdf One question to ask is, "What ELSE, besides that coax, might have changed between before when everything worked, and now, when I have RFI." Think about cable connections between equipment in the shack that might be acting as antennas to bring that RF that your antennas are radiating into the equipment. And think about this -- your antennas SHOULD be putting a lot of RF in your shack -- they must do this if they are working as antennas. Any cables connected to your equipment will act as receiving antennas. When equipment has a Pin One Problem, the RF current those antennas (interconnect cables) receive will flow into your equipment. Sometimes you can modify equipment to correct the Pin One Problem, but usually the better fix is simply make the cables a lousy RX antenna by adding a common mode choke to them. That's what you're doing when you wind some turns of the cable through a ferrite cores. Study the tutorial to understand this. And when I say "study" I mean STUDY, don't just read it through once. 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
