I'll restate: The length of coax should be as short as feasible because the losses from mismatch (SWR) are highest when compared to window or ladder line.
The shortest distance from my rig to the choke is about ten feet unless I bring the window line inside (too problematic) or put the rig in the window next to the choke (won't happen). That is what I use, ten feet of coax; the shortest possible piece, for me. Ideally it should be much shorter. I most carefully explained (rather than presuming an understanding and trying to be more clear) in the last note that adding 30' of window line resulted in different tuner values, but no change in the band segments where I could operate at reasonably low SWR ergo no significant (cumulative) change at the rig (I was still band segment limited, same places). On some (20M and up) bands, retuning was not required; it's simply two 'long wire' antennas in phase. Empirical evidence is neither right or wrong. It may bring more questions than answers, but it can't lie. The tuner likely compensated for the slight change in the feed, the antenna elements were unchanged and the end result was no effective change. Changing the coax portion length of the feed changes everything dramatically; the tuner values, the losses, lowering the SWR to give me ability anywhere 160-10. But I don't want the line losses above 40 M; it gets worse quickly above that. I only add that section in when home, I'm DXing and QRO. In this case, my findings may go against standard beliefs, but stands as evidence nonetheless. When I move the shack upstairs and replace the window line (the single strand solid copper elements make me nervous) I'll be sure to have an analyzer to make more careful measurements. In the meantime, my 'wrong' system is working. Why wrong? No part of the system (antenna or feed) is ham band resonant, which is why: It's natively high in SWR; A tuner is required; It works on all bands (the KAT3 tuner loves it, the KAT500 under QRO, not so much on 160/80); Any system change may give unexpected results. It's at a point where it works on all bands about as well one can expect for a simple wire dipole; more so considering the lack of height. Over 200 countries later, I have to say it's working. However, I miss my tower and beams... They're more effective and easier. Next house I'll get them back. I hope this answered your questions and concerns. 73, Rick wa6nhc Tiny iPhone 5 keypad, typos are inevitable > On May 17, 2014, at 11:30 PM, "Wes (N7WS)" <w...@triconet.org> wrote: > > > I said earlier: > > "Rick claims that when using a series connection of two different > transmission lines, one coaxial, one window line, changing the length of one > (coax) affects something or the other, while changing the length of the other > portion (window line) has no effect whatsoever. > > This is clearly impossible. " > > I stand by those remarks. Your empirical evidence to the contrary is wrong. > > Rick also said: > > "Changing from 10' of coax from rig to the CMC (common mode choke, typically > incorrectly called a current balun, used at the shack window) to ~35' has a > significant change in tuning and band use ability. It allows me to operate > above 300W on the bottom end of 80 meters when 10' makes it dicey (tuner > matches, but can't handle/maintain the match above 300 watts)." > > Yet earlier in the thread he said: > > "The coax portion of the feed should be as SHORT as possible, in my case it > is currently about 10' (2.8 meters). The losses are highest there and the > extreme SWR makes it MUCH worse, keep it short; use the best stuff, not the > cheap stuff. Changing the length of the coax portion has a HUGE impact on > where (or if) the system tunes; the window line, none." > > So which is it, 10' or 35'? > > With that, I'm done. > > Wes N7WS > > > ______________________________________________________________ > 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 > Message delivered to happymooseph...@gmail.com ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
