Re: K3 Autotuner malfunction

Posted by Rob KK4R on Jul 05, 2015; 6:03pm
URL: http://elecraft.85.s1.nabble.com/K3-Autotuner-malfunction-tp7604565p7604647.html

After getting some data, and considering what others had to say, the answer seems to be that there is no malfunction.  The behavior that I am seeing is likely because the mismatch with the antenna is marginal.  At least my K3 is not very sensitive to VSWR less than 1.5:1, and it reports a VSWR of 1.0:1 when other devices are measuring something more.  In general it reports a lower VSWR than any analyzer I have tried.

Addressing my "problem" on 40 meters, there are good values in the tuner memories for the whole band, but if I change from the high end of the band to the low end, the VSWR sensed by the K3 is not so bad, and I suspect that the K3 doesn't bother to switch to the values in memory for the new frequency.  I might like to see less than 1.5:1.0, but the K3 isn't bothering with it.

On 80m, my antenna actually does need a bit of tuning.  There has been some trouble auto-tuning to get a good match with the tuner around the part of the band where the tuner capacitor needs to switch from the antenna side to the transmitter side or vice versa.  This is just a theory, but possibly the K3 sensing of the match is more sensitive depending on which side the capacitor is on.  Maybe it makes a mistake sometimes when the SWR is relatively low, like less than 3.0:1.  The capacitor seems to end up on the antenna side when there would be a better match if it switched to the transmitter side.  I may mess around on 80 and see if I can learn anything else or confirm this.

Regardless, my tuner works, and if you use it correctly, there is barely a hiccup.

Rob