Björn's description of the KPA3 behavior sounds incredibly similar to issues I've been experiencing when only operating in sideband. My problem however isn't so much of an initial low power transmit, but what appears to be the complete opposite. Some of you may recall the post I submitted to the reflector several days ago about strange RF activity and my K3. In a nutshell, my SWR alarm on my wattmeter will trip upon initial keydown when operating in sideband and the linear is on. It functions fine on the other hand if I key down with a continuous carrier.. even up to 1200W. The exciter drive level doesn't seem to make too much of a difference UNLESS I turn the power output to 12W or less. The moment I switch back to 13W or higher and the KPA3 is in line, the problems begin. Looking at my wattmeter in peak mode shows an initial burst of power when keying down. After a few seconds, the power drops back to a normal level. I have a theory that there's some sort of RF burst in sideband mode upon initial keydown; perhaps the KPA3 oscillates for just a few seconds and transmits off-frequency until it stabilizes. This is just a theory though.
I'm still playing with my RF grounding and isolation to fully hope in eliminating all other possibilities before pointing the finger at the K3. 73 de James K2QI 2009/7/18 Björn Mohr b...@broadcast.se > > This problem has been around for some time with my K3. What happens > for me is that when I set the power to specific level and push TUNE > the radio stabilizes at that preset level. Then when keying and begin > talking the power level is a lot lower that verified with TUNE. After > a few seconds the power peaks are in the vicinity of the preset level, > but sometimes peaks are reaching above the preset level which makes me > reluctant to mess with TXG VCE. Another observation is that this > problem is only with the PA in line, taking power below 12 watts seems > to eliminate the issue. > > Earlier the problem was reversed as power overshot the set level in > SSB, now I am less worried but seeing the issue solved would provide > some comfort when using the amp. > > I am also using a factory calibrated LP-100A to verify my measurements. > > > 73 de Björn, > SM0MDG > SE0X > > ______________________________________________________________ > 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 > ______________________________________________________________ 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
