Holger, There is the possibility that the wattmeter in the KPA100 is not properly balanced and calibrated, and deserves to be re-checked. Calibrate the wattmeter at 80 watts rather than at 100 watts for best results.
You can expect some variation in the response of the wattmeter diodes with frequency, but not as much as you have observed. Try re-calibrating first (you must achieve a deep null before attempting calibration), and then replace the diodes if the band to band variation is still quite high. Use a non-metallic tool to adjust C1 for the null. The measurements you made at the BNC connector are not valid since you did not completely remove the KPA100. When the KPA100 is attached, that BNC connector is still connected to the input of the KPA100 and should not be used for output in that configuration (that is why a boot is supplied with the KPA100). You may want to remove the KPA100 and test the base K2 for maximum power output on all bands. If you do not have at least 10 watts of output from the base K2, you will not drive the KPA100 to a full 100 watts output. 73, Don W3FPR On 11/9/2010 7:19 AM, Holger Dörschel wrote: > Hi, I tried to drive an external linear PA with my K2/100 (no tuners > installed) and I have some issues with the output-Power: > > I used a DIAMOND SX20C and a 50 ohms dummy-load for my measurements. I also > used a Elecraft W2/2K. I think, the 2K-coupler is not the best choice but the > tendency is the same. > > 1. I mesasured at 10.0, 50 and 100W output power at the KPA100 PL-antenna > connector: > > 3.500 9.5 90 110 > 7.000 9.5 95 109 > 10.100 9.0 78 90 > 14.000 9.2 75 85 > 18.068 10.5 70 70 > 21.000 8.9 60 65 > 24.890 8.9 60 68 > 28.000 6.8 59 70 > > > 2. I measured at 10.0W output power with switched off KPA100 at the K2 > BNC-antenna connector: > > 3.500 11.0 > 7.000 10.1 > 10.100 10.1 > 14.000 10.8 > 18.068 2.8 > 21.000 2.8 > 24.890 5.0 > 28.000 8.5 > > > So I think there is a Problem with the 17-12m bands at the K2. But I think, > there is also somethink wrong with the KPA100. The Output Power at 50W is to > high. > > Any hints? > > Vy 73, Holger - DL9HDA > ______________________________________________________________ > 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
