During the 2008 10 meter contest this past weekend I experienced some power loss during USB transmissions. The K3 was set to 100 watts, more or less. The K3 firmware is the 2.58/1.94 vintage. In responding to another party calling CQ I would send my call sign, N0YE. The N0 would be transmitted at the full 100 watts. The YE would be transmitted at about 10 watts. The power level observations were made on the built in power indicator in the K3. This behavior was highly repeatable. The K3 would transmit about 4 syllables of speech at full power and drop to a low power there after. This behavior occurred with whatever I spoke while transmitting.
I used more than one antenna during the contest. Each antenna had it's own tuner and so the K3 antenna tuner was bypassed. I can not say for certain that the SWR to the rig was always better than 2:1. I do not know what I can do to get the K3 into this abnormal operational state. And I am not totally sure how I got the K3 into a “normal” operating state. I think changing power levels is one trigger to get into this abnormal state. I think going into the TUNE mode for a while is a way to get in the normal state. I also think changing bands say from 10m to 12m and back to 10m without transmitting is another way to get to the normal state. Power cycling the K3 may be another way to get to the normal state. Once in the normal mode, the K3 would function normally for a long time. After I built the K3 kit, I experienced power fluctuations while transmitting. These fluctuations were cured by grounding pins 7 and 8 onto the MIC connector shell. The K3 has functioned normally on 40m, 20m, 17m and 15m bands since that fix. The modified MIC connector was used during this contest. This other problem and fix are mentioned in the off chance there may be a connection to this 10m transmit power problem. So my questions to the group are: Is this a problem observed by others? Is this a solved problem? If this is not a solved problem, are there things I could do to mitigate the problem? Don, N0YE -- View this message in context: http://n2.nabble.com/K3-power-loss-on-10-meter-USB-tp1660124p1660124.html Sent from the Elecraft mailing list archive at Nabble.com. _______________________________________________ Elecraft mailing list Post to: [email protected] 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
