On Wed, 2010-02-24 at 18:16 -0800, Jim Brown wrote: > On Wed, 24 Feb 2010 14:18:50 -0800 (PST), callen1155 wrote: > > >I'm planning on purchasing a K3/100 but am concerned about my second floor > >shack and RF problems. > > The most important thing to understand is that a connection to EARTH has > NOTHING > to do with RFI, or RF feedback, or any of the problems you are describing.
It's amazing how widely the concept of ground is misunderstood. For years the ARRL Handbook repeated the myth that you need a good earth ground to prevent TVI. I think we finally got that straightened out. People say that your low-pass filter won't work without a ground because the shunt capacitors need to be "grounded" but then they are at a loss to explain how low-pass filters work in satellites. I think the fundamental problem is that people don't understand (or forget) that "voltage" means "potential difference", the difference in electrical potential between two points. It makes no sense to speak of the voltage "at" a particular circuit point unless you define the reference point -- the place the other lead of your voltmeter or oscilloscope is connected to. There can be 1000V difference in potential between earth and the chassis of your radio and the radio will continue to work perfectly normally as long as it is completely isolated from earth. What matters is the potential difference between the circuit nodes inside the radio, not the voltage with respect to earth. Al N1AL ______________________________________________________________ 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
