Examining the KAT3A circuit board, I doubt it can handle more than 1000 volts that a worst case random wire -- or a fault -- could cause at the output of the KAT3A tuner when the K3 is producing full rated output. But its unlikely that the KAT3A can produce full rated K3 output because of inevitable low tuner efficiency at high VSWRs.
I've never connected an antenna with a greater than 10:1 VSWR to my KAT3A tuner. I would never intentionally do that because of the stress it would could cause to the tuner components from high voltage and/or high current and inevitable poor tuner efficiency when feeding very high VSWR. Hopefully the K3's very fast acting excess VSWR detection turns down its output power before damage occurs. The K3's excess VSWR protection is very effective at preventing damage when the tuner is off. A better solution to extreme VSWR that can be caused by a truly random length antenna is to use one of the proven commercial multiband wire antennas. Just one example of a simple eight band wire antenna that definitely will not damage a K3: www.dxengineering.com/parts/pez-ef-allbandkw 73 Frank W3LPL ----- Original Message ----- From: "Walter Underwood" <wun...@wunderwood.org> To: "Elecraft Reflector" <elecraft@mailman.qth.net> Sent: Sunday, December 13, 2020 6:45:34 PM Subject: Re: [Elecraft] Tuning Random-Length Wire Antenna with K3 Internal Tuner?? I think you just proved my point. The KAT3A does not have a lower power rating for larger SWRs. That would indicate that it can handle the rated power over the entire rated SWR range. If extreme SWR at full power would exceed the component ratings, the specs would say that. This is the entire set of specs for the KAT3A: • Maximum impedance match: 10:1 SWR • Maximum power handling: 110 watts https://elecraft.com/collections/kat3a_model/products/kat3a-100w-atu I just curious why people would think that Elecraft publishes specs that their equipment does not meet. That is a pretty strong accusation. No, I didn’t check out TLW, but I have a solid understanding of transmission lines and conjugate matches, even though I only got a B- in my fields and waves class at Rice. wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On Dec 12, 2020, at 11:12 PM, David Gilbert <ab7e...@gmail.com> wrote: > > > Seriously?? Why do you think that Elecraft's tuners (like just about every > other one) have max power ratings that differ depending upon the SWR? For > example, for the KAT500 has a max power rating of 1000 watts into a 3:1 SWR > but only a 600 watt rating into a 10:1 SWR??? It can match both SWRs, but not > handle the same power at both. > > Did you bother to check out TLW like I suggested? > > Dave AB7E > > > > On 12/12/2020 8:59 PM, Walter Underwood wrote: >> Of course there are high voltages or currents in some tuning solutions. Why >> do people think the Elecraft ATU would not be designed to handle those? >> >> wunder >> K6WRU >> Walter Underwood >> CM87wj >> http://observer.wunderwood.org/ (my blog) >> >>> On Dec 12, 2020, at 7:36 PM, David Gilbert <ab7e...@gmail.com> wrote: >>> >>> >>> A matched conditon does NOT prevent the components of the tuner from seeing >>> high voltages and/or high currents. Check out TLW ... the transmission line >>> application that comes free with the ARRL Antenna Book. Pick a load that >>> gives a high SWR and then click on the "Tuner" button for the application >>> to draw one of four different tuner configurations for you. The app will >>> tell you what the voltages across each component are, and also the power >>> loss (i.e., heating effects) in each one. >>> >>> 73, >>> Dave AB7E >>> >>> >>> >>> >>> On 12/12/2020 8:18 PM, Walter Underwood wrote: >>>> Tuning happens at low power, so transients are small. After it is matched, >>>> why would the K3 ATU not be rated for full power over the full SWR range? >>>> >>>> Other components might fail, of course. Amphenol UHF connectors are only >>>> rated for 500 V. >>>> >>>> wunder >>>> K6WRU >>>> Walter Underwood >>>> CM87wj >>> ______________________________________________________________ >>> 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 wun...@wunderwood.org >> ______________________________________________________________ >> 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 ab7e...@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 wun...@wunderwood.org ______________________________________________________________ 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 donov...@starpower.net ______________________________________________________________ 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
