Thanks, Bob. I'll do just that when I get a chance. And I might just try the 1:1 also! I have an Array Solutions analyzer, been meaning to scan it to see exactly what the tuner sees. All of this requires a ladder and some creative juggling of tools/laptop etc. ;)
73 Chris On Tue, Feb 13, 2018 at 9:04 AM, Bob McGraw K4TAX <rmcg...@blomand.net> wrote: > Chris; > > Add or remove about 6 ft of the open wire line. See if this helps the 17M > issue. > > I personally don't like the idea of using a 4:1 balun and much prefer a > 1:1 current balun. With the 4:1, without measuring the Z on the coax side, > it may be the Z presented to the tuner is very low and thus outside the > range of the tuner. Additionally, it is most likely with almost every > ATU, the greatest loss occurs when the Z is low to very low. Hence my > reason for using a 1:1 and not a 4:1. > > 73 > > Bob, K4TAX > > > > On 2/13/2018 7:55 AM, Chris Hallinan wrote: > >> I have a very similar setup. K3 -> KPA500 -> MFJ 994BRT 600W autotuner >> mounted remote -> Balun Designs 4:1 -> 600 Ohm open wire line to 80 m >> doublet. >> >> It works fantastic on 80-20, but will not tune better than about 2:1 on >> 17. I cannot use the KPA500 on 17 because the SWR is too high. Nothing >> I've tried works. I'm wondering if it is simply the tuning >> range/resolution of the MFJ-994BRT? I like the idea of remote mounting, >> as >> I have only a couple feet of coax between the tuner and the balun, thus >> minimizing SWR-related feedline loss. >> >> Any suggestions for how to get it to tune on 17? >> >> 73 >> Chris - K1AY >> Punta Gorda, FL >> >> >> On Mon, Feb 12, 2018 at 12:16 PM, John W2XS <jm...@optonline.net> wrote: >> >> I replaced my Johnson Matchbox with a Balun Designs tuner balun. The >>> biggest >>> benefit is that the K3 ATU remembers the settings from band to band so >>> the >>> QSY is very rapid. I love watching the DX spots come rolling through on >>> my >>> N3FJP logging program and clicking on them to QSY to that frequency and >>> not >>> have to tune up again. I use it on 80 through 6 meters with an 80m >>> doublet >>> fed with KW ladder line (300 ohm). >>> >>> My recommendation is to keep the piece of coax from the balun to the rig >>> as >>> short as possible. This is to minimize loss since that line will most >>> likely be highly mis-matched on most bands. There was a QST article not >>> that >>> long ago which detailed the losses in that situation and I was surprised >>> at >>> how high they were. >>> >>> I once had an MFJ balanced RF Ammeter and made measurements of the JMB >>> vs. >>> the balun and they compared favorably. DJ0IP (referenced earlier) has >>> kindly put those measurements on his website. (This is in the FWIW >>> category!) >>> >>> I have not tried to substitute the tuner balun with another type but that >>> might be a future experiment. >>> >>> 73, John W2XS >>> >>> >>> >>> -- >>> Sent from: http://elecraft.365791.n2.nabble.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 challi...@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 challi...@gmail.com > -- Life is like Linux - it never stands still. ______________________________________________________________ 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
