My antenna is similar. 28.5' tall, ground mounted over twelve 28' long radials. Fed with 30 feet of RG-213. With a tuner the system works well enough on 40, 30, 20, 15. 80 Meters is the pits. Dummy Load City!
I'm considering putting a remote ATU at the base of the antenna. Basically, eliminating the 30 feet of coax feed line and all the high VSWR losses it entails. I picked 28 feet for the vertical to make it a reasonable impedance on each of my bands of interest (as well as to increase wind survivability). Another thought I've had is to put a Hustler 80 M resonator on top of it to raise the feed point impedance on 80. For now, I'll have to stick with 40 meters. - Keith KD1E - -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Vic K2VCO Sent: Wednesday, December 07, 2005 4:20 PM To: Elecraft Reflector Subject: [Elecraft] Clever antenna tuning ideas wanted OK, here is what I want to do: I have a 33' (10m) vertical with the base about 10' (3.3m) above ground. It has four 8' (2.4m) radials which are connected to the feedpoint through a coil which resonates the system on 7 MHz. It works as well or better than any vertical that I've used on 40m -- low SWR and good results. It's fed through a relatively short (20', 6m) length of RG-213. I would like to use it on 80m and 30m as well. My first try was to simply use the KAT100 to tune it. It tunes fine on both bands (1:1 at the rig), but results are fair-to-poor on 30 and poor-to-worthless on 80. On 30m, the coax losses are reasonable (the SWR on the coax is about 8 to 1, but it's very short). I suspect the problem is that the radial ground system is very poor on this band (on the other hand, the long vertical radiator should provide a slight amount of gain). So I may try paralleling a set of radials tuned for 30m. They will also be short, but resonated with a coil or stub. Does this sound like a good analysis/solution? On 80m, it's more complicated. The ground system is terrible, the radiation resistance of the vertical very low, and the SWR and losses on the coax very high. No wonder it's a dummy load! I guess the way to deal with it is to add more tuned radials in parallel and a switchable base network, but I would like to avoid any more control wires that have to go through my lightning suppression panel (I can't pass DC through the coax, either). Does anyone have any suggestions? -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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
