Most likely your antenna load Z was on the low side, increasing TX current drain. Either excess TX current or supply voltage below 11 V can cause power to revert to 5 watts.
73, Wayne N6KR ---- http://www.elecraft.com On Aug 5, 2013, at 5:46 PM, "Arno Dienhart" <[email protected]> wrote: > Hi Wayne, > > I measured with the built-in meter. Sorry, I don't have a dummy load, so I > cannot test that. Next time I will connect two of the same sealed lead acid > batteries in parallel and see if something changes. No problem to use two. > > Thank you for the explanation. At least I can be sure that nothing is wrong > with my KX3. > > 73, > Arno > > -----Original Message----- > From: Wayne Burdick [mailto:[email protected]] > Sent: Monday, August 05, 2013 17:02 > To: Arno Dienhart > Cc: [email protected] > Subject: Re: [Elecraft] KX3 power reverts from 10W back to 5W > > Hi Arno, > > The KX3 requires 11.0 volts minimum on key-down for power output levels of > greater than 5 W. We do this to ensure low IMD in SSB transmit mode, but > it's good practice in general because most 12-V batteries can be damaged > quickly if you let the voltage go much below 11.0 with a heavy load applied. > > When you measured the voltage on key-down, were you using a voltmeter at the > battery, or the one in the radio? You could have been dropping some voltage > across the power supply wires (+ and - leads probably about the same), or > in the KX3's DC input circuitry (reverse-polarity diode, current sense > resistor, etc.). So even if you read 11.7 V, it's possible that you briefly > dipped below that 11.0 threshold. > > Try running it into a dummy load, using the same battery. What is the > voltage on key-down? (Make sure to bypass the ATU or tune it into the dummy > load for this test.) > > 73, > Wayne > N6KR > > > > On Aug 5, 2013, at 2:49 PM, Arno Dienhart <[email protected]> wrote: > >> So I had set up in the park, with a charged 12V 17Ah battery >> connected. It was a hot day but I was in the shade. >> >> >> >> Every time I set power level to 10W and keyed the TX, it reverted back >> to 5W instantly. Why? >> >> >> >> The Volt meter showed 12.3 V at RX and dropped to 11.7V at TX. Was >> that the reason (getting below 12V)? >> >> Was the PA getting too hot? It never went below 5W. >> >> >> >> Thanks for any tips, >> >> >> >> 73, >> >> >> >> Arno >> >> ______________________________________________________________ >> 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 > > > > > ______________________________________________________________ > 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 ______________________________________________________________ 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
