Its really confusing, so I recommend ignoring the power out of the base K2. The rig seems to measure then correct the power out, with differences between the tune function and regular key down modes. The tune function seems to calibrate the regular key down power out...
The K2 measures the power output with a diode and resistor network off the output, so its looking at only voltage. Change the impedance or swr slightly and it changes the power out, and its VERY sensitive to the voltage/swr. I did some experiments with mine, changing the value of resistors and changing the load resistance making it about 48 ohms instead of 50, and both changed the power out a lot. Lower the voltage the diode measures and power output goes up. >From my tests, I would guess the rig can easily put out over 15 or 20 watts on all bands, but does not because its told not to. After checking with a dummy load right on the antenna jack, I found my rig would put out between 15 and 11 watts on all bands, and the power meter would read a bit high on the higher bands, thus giving slightly lower power out as the rig THINKS its putting out more power then it is. 11 or 15 watts on 15 or 10 meters, its not enough to worry about. I also think the built in antenna tuner helps things, it may be better at measuring the actual output power or taking into account the swr or something. My KPA100 has no problems doing over 120 watts out on all bands at 13.8 volts or slightly less. Its output power jumps around some, depending on swr, and the rig sometimes puts out almost full power (with or without the KPA100) when first keyed, even if the power knob is set to a low power. With the KPA100, you can sometimes watch the power jump from what its set to up 5 or 10 watts, then back to the correct value, then down 5 or 10 watts, then back up, over and over. That does not effect things when sending CW, but people driving amps with the K2 can have a hard time of it. I think power output control in the K2 could use some redesign. I am not sure how commercial rigs do it, but they are generally stable and smooth in power output. Brett N2DTS > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Jeff > Kinzli N6GQ > Sent: Sunday, April 22, 2007 11:51 PM > To: [EMAIL PROTECTED] > Cc: Elecraft Mail Posting > Subject: Re: [Elecraft] Question about K2 power meter > > Hi Don, > > Thanks for the replies. > > To answer your questions, the problem occurs into a dummy load. > > I set the base K2 (without KPA100 connected) to 5.0W, and then TUNE, > and it starts at 5.0W and heads upwards to 5.7-6.0W (read from the > display, as well as the S-meter). After about 10 seconds in TUNE, it's > up to 5.7 or 6W and the next LED on the S-meter is starting to flicker > some. > > Moving the power knob will allow me to bring it back to 5.0W, but the > next TUNE will see the power climb back up again. > > I'm not sure if I should still be looking on the RF board at this > point, or start focusing on the control board...? > > Thanks, 73, > > Jeff > > On 4/22/07, Don Wilhelm <[EMAIL PROTECTED]> wrote: > > Jeff, > > > > Another thought and a question - does the K2 control power properly > > (check with TUNE) when the requested power is set to 5 > watts? If you > > get somewhere between 4.5 and 5.5 watts output with the > requested power > > set to 5, then the power control circuits are working as > they should be. > > > > Setting the power to maximum will not readily reveal any > problems with > > the power control. > > > > OTOH, if the power output is always high then you do have a > problem in > > the power control (ALC) loop. > > > > 73, > > Don W3FPR > > > > Jeff Kinzli N6GQ wrote: > > > Don and others, > > > > > > A few weeks back, a user posted about an issue with low > power output > > > with his K2. Don said: > > > > > >> If you do not have either the KAT2, the KPA100, or the KAT100 > > >> installed, the > > >> K2 does not display the actual power output on the LCD > (the requested > > >> power > > >> is displayed briefly when the power control is changed). > What is the > > >> indication on the LED bargraph during transmit? > > > > > > I'm going through an issue with my K2 where it *appears* > to be putting > > > out too much power. With the KPA100 installed, the output > sometimes > > > jumps up to 150+W. > > > > > > I removed the KPA100 from the picture and have been > seeing if I can > > > reproduce higher than normal output with just the base > K2. So far, the > > > behavior is that if I enter TUNE mode, the indicated power on the > > > display of the K2 will rise to 16-17W. My watt meter > isn't accurate > > > enough to tell me what it's *really* putting out though, > although with > > > the KPA100 it is accurate enough to see the 150W+ peaks. > > > > > > So I was trying to think if it's really putting out 16+W, > or if the > > > power meter is really telling me it's TRYING to put it > out (because my > > > external wattmeter looks like actually less, but again > not accurate). > > > > > > I also thought maybe it's an ALC issue, because if I > rotate the power > > > knob back then back up to max, the indicated power on the > K2 will go > > > to about 15W, but the next time I do TUNE again, it again > goes back up > > > to 16+W. > > > > > > Any thoughts on this? Should I keep chasing ALC issues? > I've already > > > gone through the base K2 RF board resoldering T1-T4, reheating > > > anything that looks suspect, etc. to no avail. > > > > > > I also sent something to this effect to [EMAIL PROTECTED], I'm > just hoping > > > someone might have any ideas that I could chase down. > > > > > > Thanks, > > > > > > Jeff > > > _______________________________________________ > > > Elecraft mailing list > > > Post to: Elecraft@mailman.qth.net > > > You must be a subscriber to post to the list. > > > Subscriber Info (Addr. Change, sub, unsub etc.): > > > http://mailman.qth.net/mailman/listinfo/elecraft > > > Help: http://mailman.qth.net/subscribers.htm > > > Elecraft web page: http://www.elecraft.com > > > > > > > > _______________________________________________ > > Elecraft mailing list > > Post to: Elecraft@mailman.qth.net > > You must be a subscriber to post to the list. > > Subscriber Info (Addr. Change, sub, unsub etc.): > > http://mailman.qth.net/mailman/listinfo/elecraft > > > > Help: http://mailman.qth.net/subscribers.htm > > Elecraft web page: http://www.elecraft.com > > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
