Ken, That description sounds suspiciously like you are developing a parasitic on 40 meters. Yes, the first step in getting that under control is to install the KPA100UPKT. It was developed specifically to address a problem very similar to yours.
There is another possibility (since you mentioned the SSBA and SSBC parameters) - that you are driving the mic input too hard. switch the display to read ALC. You should have no more than 3 bars with maybe an occasional 4th. There should be no problem with an SSBC setting of 3:1 or even 4:1, but the SSBA parameter will depend on your mic. If you are using the Elecraft mics, set SSBA to 1. 73, Don W3FPR On 8/27/2010 11:42 AM, Ken Cannaday wrote: > I had an RF feedback problem on 40 meter SSB, which I brought under control, > mainly by winding a foot or two of mike cable through a ferrite core. > > However, I had been having another problem on 40 meters SSB that had gone > unnoticed until the power supply (rated at 30 amp surge) tripped out on a > voice peak. > Power control seemed okay because the output as measured on the meter in my > MFJ tuner was the same as the power setting on the K2 in Tune, Tune + > Display (override 20 watt limit), and CW modes. > > However, on SSB, the circumsatance was very different. If the setting was > for 100 watts, the meter in the tuner would often kick up to 100 watts or > more on voice peaks, whereas with my Icom transceivers, it generally will > not kick > any higher than half the power setting (i.e. 50 watts). (I really have no > good way of accurately measuring peak power on SSB and always assumed PEP > would be the same as the output in continuous carrier mode.) Turns out that > on 40 > and 30 meters, and to a lesser extent on 80, while transmitting into a dummy > load, I apparently get two to four times the expected power on voice > peaks, judging by the meter in the tuner (and applying the times two > formula). This only occurs when the KPA/100 is active. It does not occur > with the basic K2 in QRP mode. Moreover, even with KPA/100 active, if I set > compression (SSBC) and audio (SSBA) to the lowest levels, the power reading > levels appear to be similar to the Icom - about 50% of nominal power on > voice peaks. > > My KPA/100 is revision C and does not have the KPA100UPKT installed. Does > anyone have any suggestions for this problem? Would the KPA100UPKT likely > solve the problem? On the other hand, would there be any harm in setting > the > power levels and/or the SSBA and SSBC parameters so that output does not > exceed > 100 watts, and continuing to operate with the KPA100 as is? > > Any help would be greatly appreciated! > > Ken, W4NZC > > 73! > > ______________________________________________________________ > 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
