Wow. That was a great job of problem solving. In my case, I get the KPA fault with just 8 watts of drive from the K3S. So I doubt that’s my issue.
Carl Yaffey K8NU Recording studio. [email protected] 614 268 6353, Columbus OH http://www.carl-yaffey.com http://www.grassahol.com http://www.bluesswing.com On Dec 5, 2016, 2:07 PM -0500, David Olean <[email protected]>, wrote: > Last summer a friend of mine got a new K3s and had problems with it on > just six meters. As soon as he raised power above about 10 watts, the > SWR reading went crazy and the rig gave high VSWR warnings. He checked > his six meter yagi with another SWR analyzer and the antenna checked > good. After goofing around with it and getting nowhere, he brought it > over to my place and we tried it on my six meter array. We saw the same > problem here, high VSWR, but with different combinations of antennas, > the K3s actually worked OK. It also worked fine into a dummy load. I > got suspicious and tested the K3s with a spectrum analyzer. Sure enough > the rig had a huge parasitic oscillation on about 27.4 MHz and with most > of the power there, you could see how the radio would show a high SWR. > It only appeared when the internal 100w PA kicked in. He did not have a > KPA-500. This was just a K3s. > > He sent the K3s back to the factory along with some pictures of the HP > spectrum analyzer screen. I am not sure if they duplicated the problem > at the factory, but they applied a few changes to the PA and now it is > all OK. If the K3s was to have an unwanted oscillation, it would sure > mess up the KPA-500 and show high VSWR and maybe damage some filter > components. If all else fails, that may be a place to look. > > Dave K1WHS > > > > > > > > On 12/4/2016 6:30 AM, Mike va3mw wrote: > > > As quoted > > > > > > If the amp works on a dummy load, then look beyond the amp at this > > > time until you have eliminated everything else. > > > > > > Somewhere else you are getting a voltage breakdown that is arcing and > > > tripping off the amp due to high swr. An MFJ analyzer will not show > > > that. > > > > > > Mike va3mw > > > > > > > On Dec 4, 2016, at 12:54 AM, Jim Brown <[email protected] > > > > wrote: > > > > > > > > > On Sat,12/3/2016 9:41 PM, Vic Rosenthal wrote: > > > > > Look at any cables, switches and connectors that are common to the > > > > > various antennas. > > > > Yes. Lots of "off-brand" coax is junk. So are most un-branded > > > > connectors. If the PL29-style connector doesn't say Amphenol 83-1SP, > > > > it's probably junk. How well is the connector soldered or crimped? > > > > If crimped, was it done with the "official" crimper for the > > > > "official" crimp connector that matches THAT specific coax? If not, > > > > it's suspect. > > > > > > > > Are you using any of those shiny adapters that are sold at hamfests > > > > for a few bucks? They're JUNK! Ask me how I know. :) They have > > > > caused me many problems that were tricky to diagnose. > > > > > > > > IMO, the only GOOD coax connectors say "Amphenol" on them, or are > > > > ancient MIL-spec parts with MIL numbers stamped into them. I snap up > > > > stuff like this when I find it at ham flea markets. > > > > > > > > 73, Jim K9YC > > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
