Stuart wrote: >Even simpler is a 80m dipole fed with balanced line to a tuner for all band >use. The window line is less costly than coax. A good quality tuner is >less lossy in multiband use than coax/ tuner balun, etc.. Balanced antennas >have fewer problems than off center feeds. Balanced line to dipole does not >need a balun at the antenna.
That's always seemed the ideal approach to me. You can go anywhere with it with very low resulting losses, which is also very useful for MARS/CAP/SHARES work on those odd HF military frequencies. The only real problem seems to be routing the balanced line from the antenna into the shack without it having much interaction with nearby materials. A second problem is the lack of real balanced-line antenna tuners. Unbalanced tuners with that small output balun are problematic. I bought an old Johnson Matchbox just because it is one of the few true balanced tuners can can still be found. I know that MFJ has a couple of non-balun tuners design for balanced line, but I've never investivated their technical details, nor read reports on how well they perform. Obviously, these would not serve the "gotta swap bands in five seconds" contest crowd, but that's not me. I never trusted those resistor-terminated folding dipoles. Every analysis of them that I've ever read over the past 30 years has been basically unfavorable, as one would expect, with performance at best very much below that of a simple dipole. It is similar to a broad-band antenna design using any length of center-fed non-folded dipole fed with coax, with a hefty 50-ohm resistor across the coax leads at the connection to the dipole. You'd get good VSWR with that from 1.8 to 30 MHz! Come to think of it, about 25 years ago some outfit was hawking something just like that to hams at high cost. Yet, I'm sure you could make some contacts with it, just like you can with a resistor-terminated folded dipole. What these types of antennas show is that, no matter how bad an antenna design is, it'll work sometimes. TANSTAAFL! Mike / KK5F _______________________________________________ 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
