In my last home I had a short (15' or so) coax from the ATU to a balun outside, and ladder line from the balun to the center of an all-band dipole. I found it much more convenient to run coax through the wall than ladder line. I plan to duplicate this in my new home (under construction). I have found an all-band dipole a great thing to have handy.
I'll be feeding a multiband vertical antenna (a HyTower) several hundred feet my shack. I'm not yet sure if I'll use surplus CATV hardline or a good-quality coax. The HyTower is resonant on some parts of the bands I want to use, but it needs a little ATU help in some places. It's hard work to cover all of 3.5 to 4 MHz (although broadband antennas exist). Some commercial tuners with provision for a balanced line (like my Nye-Viking MB-V-A) use an internal balun. I found it easier to put a balun on the outside of the shack wall. My older 40 meter antenna was cut for the CW end of the band, and when I wanted to use it on phone I had to use the Nye-Viking for help. I was busy in phone contests, working people split frequency. I've solved that in two ways, I'm going to use a KAT500, and my new 40 meter antenna (a W6NL design Moxon) is broad banded. There are a good range of SWRs (e.g. 2:1) that don't introduce all that much loss if the coax is good, the run isn't all that long, and the frequency isn't that high. You lose a lot more power at high SWR on 2 meters than 80 meters. I use N6BV's "Transmission Line for Windows" (TLW) software, which came with my Antenna Book, to understand how much loss I'm going to suffer with various transmission lines at various SWR values. I am also inspired by Walt Maxwell's assertion in "Unimportance of Low SWR Values" in his Reflections III, where he states, "From the viewpoint of amateur communications, it can be shown mathematically, and easily verified in practice, that the difference in power transferred through any coaxial line with an SWR of 2:1 is imperceptible compared to having a perfectly matched 1:1 termination". I believe him, but my solid-state amplifier is happier at 1.5:1 than 2:1, so I need to provide some impedance transformation help. In the shack, where it's easy to change. I'm not planning high SWR runs at a long distance unless I have better than average coax transmission line. I've found some surplus 75-ohm CATV hardline to feed that HyTower out in the woods. It'll present an impedance mismatch right at the start. I don't care; the ATU will provide the necessary transformation. And I also don't care what the ladder line SWR is. I do worry about how the balun performs at high SWR. I may also run 12V DC on the coax to the HyTower and switch in some lumped reactance to help with the 80 meter phone/CW transition and perhaps some similar help on 160. Haven't figured that out yet. 73 de Dick, K6KR -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim Miller Sent: Sunday, June 17, 2012 5:00 PM To: Elecraft Reflector Subject: [Elecraft] KAT500 usage model? > What sort of feedline and antennas are folks expecting to use with the KAT500? Jim ab3cv ______________________________________________________________ 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
