On Tue, Nov 1, 2011 at 9:24 PM, Joe Ford <k4...@yahoo.com> wrote: ... I'll take down the ant and inspect it.But it works fine on all the other > bands. Tunes with no problems all other bands. The KAT100 tunes but the KAT3 > doesn't?
Tuning all bands using a single antenna is always dicey somewhere.Success is NOT guaranteed, but fortunate. You are often operating at the fringe of a tuner's range on one band or another. The KAT 100 and KAT3 are not the same tuners, have different coils, different tradeoffs, and different firmware to drive it. Though the ranges are approximately the same, give the two units an impedance at the far fringe, and one or the other may not be able tune it properly. Change any of the coax lengths after the tuner, INCLUDING THOSE INSIDE THE K3, by switching, exchange, or whatever, and what just barely got tuned the last time by the same tuner may not now tune. Though this may not be your problem at all, a friend of mine was having troubles of this mysterious sort. Eventually he discovered that he had not soldered either the braid OR the center conductor on a PL259. It worked for YEARS before it finally started getting intermittent. Another ham had a balun that was gradually going bad and overheating, apparently shorting some turns and causing mysterious changes in SWR. He discovered that because during a QRO contest it caught fire and completely shorted out. Actually his wife discovered it looking out the window at the tower out in the field, and came and told him his tower was on fire. The way to validate and check out one of these compromise antennas, is to run it when it is brand new and working spiffy. SWEEP the MFJ CONTINUOUSLY from the bottom of the lowest band to the top of the highest band. Note the actual resonances you find along the way. Write down those frequencies, the R at those resonant frequencies, and the 2:1 SWR points above and below all of those resonances. Entirely possible that all of the resonances are outside the ham bands. Keep these figures as a reference. When you have trouble, repeat the measurements. IF there is trouble in the antenna, those readings will change. If the coax gets waterlogged, the 2:1 SWR points will broaden out significantly and the R values at resonance will likely change. If something gets broken the resonances will all move on you. If you have an AIM 4170 as your analyzer, just sweep it from 0.5 to 30 MHz and save the file. You can then import it and have an onscreen compare between the old and new readings. 73, Guy. ______________________________________________________________ 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
