> Does anyone have any experience with trying to match one > of these 43-ft > verticals, that are being offered by several > manufacturers, using the K2s > internal ATU? Is it able to find a match on 80-meter CW? > Are there any > particular brands of 43-ft verticals that you like or > don't like? Most of these > verticals that I have seen are in the mid to upper $300 > range, except for the > fiberglass one from S9 Antennas. Any opinions on that > particular antenna?
Paul, I know power limits are not the problem with the K2 barefoot, but consider on 80 meters the base impedance of a fat 43 foot vertical with a modest radial system is about 12 - J 290 ohms. It would be worse with a thin wire. You would have to supply almost 1200 volts peak at almost 3 amperes to the antenna base to apply 100 watts on 80 meters. Since the 50 ohm SWR is over 100:1 on 80, it would be very difficult to get a significant percentage of your transmitter power into it on 80 (and impossible on 160) unless you put a real matching system right at the antenna. (and no, an unun is not a matching system and won't fix 80.) On 60 and 40 meters things are OK. SWR is under 6:1 so feedline efficiency would be OK without the unun. On 30 and 20 things are tough again, but far more workable than 80 and the unun at the base would help. Without the unun SWR is about 30:1. With the 4:1 unun maybe 8:1 SWR. Personally the only way I would have an antenna like that is if I remoted a good tuner right at the base. Otherwise I'd buy a trap vertical like a 6BTV or that Butternut vertical that actually has things that act like traps but that are not called traps by name. Overall, unless you put a tuner very close to the antenna, a trap vertical would work a whole lot better. For 80 you could base load the thing, and a 43 foot vertical with a good ground would be decent. Just make sure the antenna has a good base insulator, because at 100 watts you'd have over 1000 volts at the antenna base. DX Engineering has the best mechanical construction and a very good base insulator. 73 Tom ______________________________________________________________ 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
