The SWR circuitry in the KXAT100 (and KAT500) measure the forward and reverse voltage values at different times. They cannot be measured simultaneously because they don't have dual A/D converters or sample-and-hold circuits. To be sure, there is only a short time between sampling the forward and reverse directions but if your output power is changing with time as it will with a high speed CW signals and more especially and more troublesomely with a SSB signal, the SWR metering may indicate an incorrect value. If you have the tuner in AUTO mode, this may trigger a retune. For this reason it is best to operate either of these tuners in MAN mode and train the tuner(s) to store good L-C values for different frequencies in each of your operational bands. The tuners store this information in "frequency buckets" and when they detect the frequency within that bucker they recall the L-C values and if they need to be changed they will be.
Summary: Train the tuner so that it can remember the L-C values to use for a specific range of frequencies. Don't use AUTO mode; use MAN mode. Cheers and 73, Fred KE7X "The Elecraft K3: Design, Configuration and Operation 2nd ed" "The Elecraft KX3 - Going for the summit" "The Elecraft KPA500 and KAT500 - the K-Line Dream Station" Printed, coil bound copies of these are all available at www.elecraft.com KPA500 and KAT500 Quick Set Up Guide http://www.ke7x.com/home/k-line-introduction-and-set-up-guide > -----Original Message----- > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of > Jim Kutsch, KY2D > Sent: Monday, December 08, 2014 9:18 AM > To: Elecraft@mailman.qth.net > Subject: Re: [Elecraft] KXPA100 Intermittent VSWR Issues > > I'm experiencing the same thing but mostly on 40 meters where the best > match with the ATU isn't as good as on other bands. It *SEEMS* to have > started Saturday when I installed the latest KX3 beta and set > compression to 20. The antenna is a Carolina Windham. > > 73, Jim, KY2D > . > > > -----Original Message----- > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of > Jim Stahl via Elecraft > Sent: Sunday, December 07, 2014 10:08 PM > To: elecraft@mailman.qth.net > Subject: [Elecraft] KXPA100 Intermittent VSWR Issues > > I've run into several occasions where in mid-CW transmission my KXPA100 > (with internal tuner) SWR takes a momentary jump from matched to maybe > 3:1. > I see the SWR jump on both the KXPA front panel LEDs and on the KX3 > VSWR display. It lasts for maybe half a second, I hear several clicks > of the relays in the tuner, and them it's back to normal. When normal > the SWR is pretty much 1:1 on the KX3, and the second green LED lit on > the KX3. I've not seen it happen at the start of a transmission, but > rather several characters into a CQ or exchange.. > > In the ARRL 160 contest Saturday night this was happening perhaps once > every > 2-3 minutes. I'm using a fairly well matched antenna - not random > wires. > I also encountered this problem on 15 meters when operating from > W1AW/8 in WV in October. In both cases I was running a pretty high CW > duty cycle while running at a pretty good clip. The amp was warm, but > the heat sink air flow is not blocked. > > Any thoughts? > > > 73 - Jim K8MR > > > > > ______________________________________________________________ > 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 jim.kut...@ky2d.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 fc...@ece.montana.edu ______________________________________________________________ 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
