Chuck, I operate a K3/100 from a 2nd story shack and have significant RF ground problems. I do have a good powerline ground, but that is irrelevant. My antenna is a 100 ft sloper, centerfed with over 100 ft of 450 ohm window line (perpendicular to the antenna for 75 ft). It will "load up" on all bands 160M through 6M, with varying degrees of effectiveness. I cannot run my amplifier (Alpha 78) at more than 200-300 watts on most bands without significant RF problems, including tripping GFIs. I intend to try to alleviate the problems with a tuned ground, using a series-tuned resonant circuit in a counterpoise system hanging out the window, an arrangement similar to the MFJ 931. (If you look inside one of those, you will see that it is very cheaply made. You can do much better with your own coil, capacitor, and RF ammeter.) By the way, I can operate the K3/100 barefoot without apparent adverse effects due to the bad RF grounding.
Another issue only distantly related to grounding is that the K3, like the K2, is extremely susceptible to ESD strikes. That is a huge problem for me in the dry, high desert of Nevada. You cannot touch anything here without drawing a significant spark, any time of year. I quickly caused expensive major damage (destruction of firmware, etc) to my K2/100 by touching it, even though it was carefully grounded to power system ground. The K3 is upset by such strikes also. I try to avoid damage by using an operating table with conductive paint (Walmart) and a good (DC) ground system, so that I can continuously discharge myself before and while operating. The reason for the ESD susceptibility of the K3 and K2 is flawed shielding design and (apparently) lack of ESD mitigation in the circuitry/layout. Jerry AI6L -----Original Message----- From: callen1155 [mailto:callen1...@yahoo.com] Sent: Wednesday, February 24, 2010 2:19 PM To: elecraft@mailman.qth.net Subject: [Elecraft] K3/100 -Second floor- no RF ground ?? 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. I'm using my K2/15 and don't have problems but previously with my old Knwd TS 830 at about 100 watts the vibroplex bug would 'bite' me. I'd also get some RFI on the TV (didn't try any filters to prevent it). I know both of the above arrangements are potential sources for RF problems. What I don't know is whether RF problems (both the 'burn' and RFI) are radio related; i.e. are some radios more prone cause issues and how is the K3/100 in this regard as compared to the TS 830? (this may be a non-question-- i just don't have enough experience with different radios to know). So I'm wonder if any of you operate a K3/100 from a second floor shack, with no RF ground, (guess it's too much to ask about a semi-indoor antenna) and if you're experiencing RF problems? Also, if I experience RF problems with the K3 do any you have any experience with an "Artificial RF Ground" such as the MFJ-931? Sorry about being long winded. Hope I'm not 'destined' to order a K3/10 instead. thanks again. chuck af4xk -- View this message in context: http://n2.nabble.com/K3-100-Second-floor-no-RF-ground-tp4628979p4628979.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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
