Good Q's Ron. The antenna is a 28' tall home-brew vertical using telescoping sections of alum. tubing. I put Penetrox at all the joints to avoid issues. No traps or anything, just a big piece of alum sticking up in the air. It is U-bolted to a pressure treated 4x4 buried in the ground. I have 15 radials buried a couple of inches down. Each radial is 20 feet long IIRC. It's been up since about Nov.
Yes, indeed, narrow bandwidth on a shorter-than-quarter-wave vertical can be a good sign that efficiency is up. My antenna is fairly close to 1/4 wave and with only 15 radials, having bandwidth of about 250 KHz at 7 MHz is not unreasonable. With the bandwidth suddenly dropping to 90 KHz, that sounds like the vertical just got shorter. I wonder if the top broke off? :-) The feedline is bolted to the base of the radiator and the braid is bolted to the radial plate. The feedline itself is 6 months old. I coated the antenna end of the feedline with coax seal to prevent water from working its way back up into the coax. I even mounted the coax a foot or so up the 4x4 post and brought the connection end down to the antenna so the water would drip down and off the end rather than back into the coax. So I doubt it is an issue with the coax itself. I'll find it eventually. Maybe a bad PL259 on the RG213 coax. Maybe an issue inside the tuner. One thing is sure, I won't need a solder sucker to fix the problem :-) 73! - Keith - -----Original Message----- From: Ron D'Eau Claire [mailto:[EMAIL PROTECTED] Sent: Wednesday, April 19, 2006 4:36 PM To: Darwin, Keith; 'elecraft' Subject: RE: [Elecraft] K2 problem or is it the antenna? Keith wrote: Also, the bandwidth of the tuned system has become much narrower. I used to get 2:1 bandwidth across most of the 40 meter band. Two nights ago, I struggled to get 2:1 over 90 KHz. ---------------- Narrow bandwidth is a sure sign of a reasonably efficient, but physically small antenna compared to the wavelength. That would cause me to look at something intermittent in the antenna itself that is disconnecting part of the radiator. You said it was a ground mounted vertical. Does it have any traps or other bits beyond a vertical radiator? I'd sure look for a connection that is opening up, as you mentioned. Possibly even an intermittent feedline connection to the antenna. Ron AC7AC _______________________________________________ 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
