I have been having problems with my K3 auto tuner using an antenna that has worked well and been tuning easily for nearly all bands. My first reaction was to assume the antenna, an 80m horizontal loop, was the problem, but I am now convinced otherwise. To prove that, I did the following: - took the antenna down, refurbished it, and replaced the feed line (not wasted energy); - tried other baluns; - confirmed that my LDG tuner has no problem tuning; and - tuned it manually with the K3 tuner.
The problem behavior is this. On 40m and 80m, the K3 will not find a decent SWR (<1.7:1) when auto-tuning. On 80m it has done fine tuning one direction across the band and failed going the other direction over a significant portion of the band. This is repeatable. On 40m, the SWR for the antenna system at the rig end is only about 1.7:1 at the low end and 1.4 at the high end. At the low end, the K3 tuner will not find a match under when the ATU TUNE button is used, except in particular circumstances. Using the menu system to check tuner values, it ends up with the capacitor connected at the antenna side at a low value and with a low value of series inductance. Effectively this is near the bypass mode. Hitting the ATU TUNE button to cause a long tune cycle makes no difference. Manually, the capacitor can be switched to the transmitter side, and a match near 1:1 is easily set by adjusting L and C. Today I cleared the memory on 40m and manually tuned at a low frequency in the band. Then, moving up the band at 2KHz intervals, the auto tuner was able to quickly fine tune the match and a full set of memories was created. This means that I can work 40m without a problem without hitting the ATU TUNE button, but if the ATU TUNE button is hit after a significant frequency change, the match is lost. Therefore, the key problem with the auto-tuner behavior is that when ATU TUNE is used in a case where there is no nearby memory, or a large frequency change has been made since the last transmission, the tuning algorithm apparently does not try switching the capacitor from the antenna side to the transmitter side, and the tuner does not thoroughly look for a match. Is this abnormal behavior for my unit, or is this a quirk of the system? Thanks, Rob, KK4R -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Autotuner-malfunction-tp7604565.html Sent from the Elecraft mailing list archive at 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 arch...@mail-archive.com
