On Apr 4, 2010, at 4/4 6:50 AM, chen dave wrote: > I use K3 internal 2 tones test function + SDR-IQ+ SpectraVue3.
Are you ignoring the crest factor of the two tone test signal? To get 100 watts average RF power from a "two tone" signal, the instantaneous peak power has to be nearly 200 watts. Assuming that you are not clipping the A/D converter of the receiver, I suspect that your K3's PA may either be clipping on the voltage rail or the PA is being ALC'ed. This is why when I tested the PSK31 transmit IMD on my K3 (here: http://homepage.mac.com/chen/Technical/K3/Digital/digital.html ), I had limited the output (average) RF power to 50 watts. Note that when BPSK31 (or QPSK31) transmits the idle Varicode, it is precisely a "two-tone" signal (i.e., double sideband suppressed carrier signal that is modulated by a sinusoidal AF tone). In the case of PSK31, the AF tone is a sine wave at 15.625 Hz (the I and Q signals are cosinusoidally varying between each PSK31 symbol at a period of 31.25 symbols/sec). 73 Chen, W7AY ______________________________________________________________ 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
