Steve 40 seems to be the killer band for weird things. Dave's comments are the first place to look. Try also changing jumper cables.
What also could be happening is RF flowing back on feedline in a common mode. This RF gets measured as return energy and now, since the power is higher, the return currents are higher and hence the high SWR reading. You won't see this with your RigExpert. Does the same problem happen into a dummy load? If Yes, it is an amp issue. If no, it is a antenna/feedline issue. I would try some RF chokes (Mix 43) on both ends of the feedline (antenna and amp end). I chased strange RF issues for decades until I read this document by the YCCC/W1HIS. http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf. After that I bought about 100 Mix 43 chokes and added them everywhere. Not only does it help with unique RFI TX issues, it also helps with the ability to hear. The quieter you are, the more you can copy. Let us know how you make out. Mike va3mw On Sun, Sep 15, 2019 at 8:05 PM <rocke...@gmail.com> wrote: > Check your connections. Loose or poor PL-259s. Also check to see if the > antenna is close to something causing it to arc over. I had one antenna > that > used ladder line with solid conductors. Due to it moving around in the wind > one of the conductors developed a break which tested fine under low power > or > with an analyzer but would have problems at higher power. I've since moved > to Davis RF copper clad stranded ladder line. > > Dave wo2x > > > > > -----Original Message----- > From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> > On > Behalf Of Stephen Rabinowitz > Sent: Sunday, September 15, 2019 7:58 PM > To: elecraft@mailman.qth.net > Subject: [Elecraft] Reflected power > > My KPA-1500 switches from operate to standby due to reflected power more > than 200w whenever drive power exceeds about 8 watts on 7 MHz. The forward > power at that point is about 400w. The antenna is a double bazooka that > shows an SWR of about 1.2 on a RigExpert AA-230Pro antenna analyzer. A > Telepost LP-100A digital wattmeter shows SWR 1.3 with Z=52, R=49, Ph=17, > and > X=15. The KP1500 tunes to an SWR of what it labels 1.1 on that frequency. > The latest firmware, version 2.27 is installed. This problem does not occur > with double bazooka antennas on 80m or 30m, or with Yagis from 20m to 6m. > It > seems to me that there is a brief surge in reflected power at the very > onset > of the transmission that triggers the response, but that the reflected > power > quickly decreases to normal levels of just a few watts. Any ideas for > dealing with this problem would be much appreciated. > 73, Steve K2SN > > ______________________________________________________________ > 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 rocke...@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 va...@portcredit.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
