Paul, In addition to the points in my last post, a check of the feedpoint impedance (with an antenna analyzer) at the end of the parallel line would be informative. If you have an 80 meter radiator and a feedline that is close to a half wavelength on 40 meters (34 feet or some multiple of that length), the feedpoint impedance will be very high. You might do well to try adding a 15 foot length of parallel feedline.
I would advocate that a 1:1 balun will usually serve you better than a 4:1. It is not the characteristic impedance of the balanced line that is to be matched, but the actual feedpoint impedance of the feedline at the point where the balun is inserted - it all depends on the electrical feedline length and the electrical length of the radiator. An 80 meter radiator used on 40 meters is "two halfwaves in phase" which has a high feedpoint impedance at the antenna feedpoint, one must use a balanced feedline that has an electrical length of 1/4 wavelength or an odd multiple thereof to bring the feedpoint impedance down to a reasonable level. 73, Don W3FPR On 5/4/2011 7:49 PM, Paul Agoglia wrote: > I ran a transmit test today on my recently built (serial 7059) K2/100, with > SSB adaptor, KAT 100 antenna tuner and elecraft balun. For the station > antenna, I have an 80 meter dipole with each leg currently cut to 66 feet. > The center of the dipole is not quite 40 feet high. The two ends are > inverted downward and are each 10 feet off the ground. All three points of > the antenna are anchored in trees. > > The antenna is fed to the shack with 165 feet of The Wireman 'window' ladder > line > > I used my microphone to call a CQ on 40 meters, and the KAT 100 lit up like a > Holiday Tree. SWR all the way to the red zone. I tried this at various > power settings up to 100 watts, and only transmitted long enough to see how > many lights I got. Always to the end of the scale. I used a separate SWR > meter and was getting readings of 7:1. > > I switched to a 300 watt dummy load from the 80 meter dipole, and the SWR > reading on the KAT 100 was perfect. Just one light lit up. > > I also did a continuity check between the two lines on the ladder line to > verify I did not have a short. OK there. > > Any suggestions? Is it possible that all I need to do at this point is trim > the antenna? Or do I have something internal going on? > > 73 de WN2K > Paul Agoglia > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
