Thanks for all of the very good information and suggestions. My counterpoise had been several wires running together - I wasn't aware of the need to separate the ends. So, I removed the counterpoise that I had and made 3 new separate ones, 1/4 wave for 15, 17 & 20 meters, cut for the middle of the phone band on each. These are attached to the grounding screw on my KAT100 and run in 3 different directions... and guess what? The problem is still there. Measuring with my field strength meter, there appears to be no appreciable difference in the level of RF in the shack on these bands.
On to the next things to try, which will have to wait until the weekend when I can hang out of my window during daylight. The next things I'll try are 1) attach the counterpoises directly to the coax ground on the balun, 2) replace the 9:1 voltage balun with a 4:1/1:1 current balun, 3) running more, and different lengths of wire from the KAT100 to the ground rod (although if the counterpoises have little affect, would this have any different affect?) 4) changing the length of ladder line to the balun and the length of coax from the balun to the KAT100 (I don't have a lot of room for flexibility here). I'll let you know the results. Thanks again for all of the information and suggestion. Bob W1SRB -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Solosko, Robert B (Bob) Sent: Monday, January 22, 2007 12:57 PM To: [email protected] Subject: [Elecraft] Rf in the shack distorting audio Hello All, Several month ago, after I finished my KPA100, I found that when transmitting SSB on the higher bands (20, 17 & 15), the computer speakers across the room, when turned on, would screech - adjusting the speaker volume had no effect (but turning off the speakers quieted them). During a QSO a few weeks ago, it was commented that it sounded like I was getting RF into my audio. To make a short story long, I don't have a very good ground system, so there's a high level of RF in the shack - the shack is on the 2nd floor, about 18 ft above the ground rod. My primary antenna is a 100 ft multiband horizontal dipole feed with ladder line into a 9:1 balun, which is connected to my KAT100 via 6' of RG8. While the antenna works great on all bands (the KAT100 has no trouble tuning it), there's a fairly high SWR on the feedline on the higher bands. I have two different length wires connected the ground rod to the KAT100, and adding counterpoises for 20, 17 & 15 meters hasn't change the high level of RF in the shack on these bands. A week or two ago, I put up a second antenna, a vertical parallel dipole for 20, 17 & 15 meters, fed with RG8 - this antenna has very low SWR on these bands. When using this antenna, I have no problems with the computer speakers screeching, so there's apparently not much RF in the shack. This weekend, during the NA QSO party, when using the ladder line fed dipole on the higher bands, several times, I was told that my audio was distorted, and switching to the vertical coax fed dipole immediately cured the problem. So, the question is, what can be done to fix the distorted audio when there a high level of RF in the shack (besides getting a better ground system - I plan to put in one or two more ground rods, but I won't be able to do that until after the ground defrosts in the spring). The mic I'm using is a RadioShack Electret replacement element in an old mobile mic case - the case is plastic and not shielded, but the cable is shielded, and I have grounded the mike jack in my K2. All suggestions about how I can eliminate the distortion will be greatly welcomed, as well as suggestions about how I can reduce the high level of RF in the shack besides adding more ground rods. Thanks Bob W1SRB _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
