Chuck, I have an almost identical setup to what you are proposing. It's really difficult to get an effective RF ground on an upper story because the ground connection has resonance which may result in a high impedance at higher frequencies. Some people have suggested an MFJ Artificial Ground but that basically tunes up a wire counterpoise inside the house and I can't see how that can be good either for low noise or RFI immunity because the wire must pick up noise and radiate signal.
My two HF antennas are an MFJ magnetic loop and a multiband dipole. I have a balun on the dipole, and I have never experienced RF on the radio though I do get a strong field from the magnetic loop that can cause the computer to act up at high power. I don't regret getting the 100W PA for my K3 as I was getting frustrated with QRP during the years of no sunspots and now I'm used to having it I can't easily put the genie back in the bottle, but QRP is really preferable for many reasons in this kind of situation. I have experienced the common mode pickup that has been mentioned where RF radiated by one antenna was picked up by the feeder of another and fed back down to the shack. It really started when I added 2m antennas to my attic antenna farm. I would probably never have noticed if I was not a keen PSK31 operator and have an IMD meter but the effect is noticeable as poor transmit IMD on some HF frequencies. The problem is really only solvable by getting rid of the 2m antennas, but I have managed to mitigate it to some extent by making copious use of clamp-on ferrite suppressors on every cable that goes into the K3. I also found that "grounding" the equipment to the copper pipes of the central heating system was actually making it worse. If you just have the one antenna then hopefully you won't have the problem this bad and won't need to go to such lengths, but I have been trying to push the envelope of what can be achieved with an indoor antenna system. callen1155 wrote: > > > Hello guys, > > I'm planning on purchasing a K3/100 but am concerned about my second floor > shack and RF problems. > > First of all: > 1) I don't have an RF ground (don't really want to drill thru the house > and siding for the ground strap) and > > 2) my antenna is a semi-indoor/attic dipole (HOA). > I'm running a coax from the second floor radio to the attic where i attach > to a dipole (no balun) and the dipole runs the length of the house each > way and out the eaves where both wires run out about 35 yards to the > trees. > ----- Julian, G4ILO. K2 #392 K3 #222. * G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html -- View this message in context: http://n2.nabble.com/K3-100-Second-floor-no-RF-ground-tp4628979p4631563.html Sent from the [K3] mailing list archive at Nabble.com. ______________________________________________________________ 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
