I recently got a new K3s/10 built up and running. This week I ran some tests to get familiar with it and one test that surprised me was the high Tx IMD levels. I first noticed that the two tone waveform on a Tek o'scope showed flat topping starting at about 4.5 W. As the power level was increased the flat topping got worse. I checked the spectrum with my HP spectrum analyzer (on 14 MHz) and measured the following 3rd order IMD levels feeding a 1.1 SWR:
1 W: -36 dBc 4 W: -31 dBc 4.5 W: -33 dBc 6 W: -34 dBc 8 W: -25 dBc 10 W: -21 dBc It was interesting that as the power was increased from 4.5 to 6 watts, the increased distortion didn't show up in the 3 rd order IMD, but rather the 5 th and higher order products. Since I am new to Elecraft radios, I don't know if this behavior is expected or if there is something in my transmitter that needs to be checked out. I have built up a number of amps over the years and I am used to seeing flat topping start at, or a little below the maximum CW output power. My K3s puts out about 12 W max, so I was expecting the flat topping to start at about 11 W. Bill N0CU -- View this message in context: http://elecraft.365791.n2.nabble.com/High-Tx-IMD-with-new-K3s-10-tp7617100.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
