Ian, This sounds like an intermittent connection somewhere, possibly in the 10-W amplifier stage.
Try re-tightening all of the hardware on the bottom covers, including the screws that hold the PA device tabs to bottom cover B. Also try reseating the 10-W amp module. If this doesn't help, try measuring the 0-dBm drive at the XVTR OUT jack. For this purpose you need to put CONFIG:KXV3B into TEST mode. If you get a full 0 to 1.5 dBm output at XVTR OUT (into a 50-ohm load), but low power output from the 10-W amp module, then the latter is probably implicated. Look at both sides of the module very carefully to see if a component is not soldered at one end, etc. This is rare but it can happen. Also look at the components on the RF board just behind the 10-W amp module. I can give you more detailed signal tracing info if needed. Wayne N6KR On Sep 12, 2015, at 1:57 PM, "Ian White" <[email protected]> wrote: > My K3S/100 has gone into an unusual state where the maximum power > available - on any mode, any band - is about 1.5-2W. This is independent > of any PWR setting above 1W, and the PA does not engage at higher PWR > settings. > > All this began on Friday afternoon when I switched on the rig. The K3S > had been working normally a few weeks ago, but hadn't been used for > transmitting in the meantime. > > An external power meter confirmed that the TX could not deliver more > than about 1.5-2W. This was confirmed again by the failure messages > from a TX power calibration. While troubleshooting, I progressively > uninstalled the KPA3 followed by the KPAIO3A adapter board, but with no > change. Even in the simplest 10W configuration with only the small > bridge board in place between the two PA connectors, the K3S would still > only deliver 1.5-2W with no effective PWR control. > > I also tried most of the other common tests: unplugged everything else; > reloaded an older saved configuration; EEINIT; reloaded the saved > configuration again. No change. > > But I also noticed that the firmware was one release behind the times, > so for lack of any other ideas I did a complete firmware upgrade to the > latest MCU 5.35 / DSP 2.86 / FPF 1.24 - and it started working again! > Normal power output up to 10W, and fully variable up to 100W after > reinstalling the PA module. Another TX calibration confirmed that > everything was fine. > > That pleasant surprise seemed to indicate that the problem had been more > related to firmware than to hardware. > > By Friday evening, I believed the problem had gone away... but I should > have known better. > > Today it has failed again, exactly the same way as before. Reloading the > same latest firmware didn't work a second time. > > So now it's the weekend and I'm all out of ideas. > > While I wait until Monday to contact Elecraft Support, could anyone in > the group offer any suggestions, please? > > > 73 from Ian GM3SEK > > > > ______________________________________________________________ > 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]
