Hi I have tried to improve my IMD test setup. It is far from perfect, but I have got rid of the broadcast station by bulding "quick and dirty " Xtal 4 MHz oscillator. It is built using a BC547 NPN bipolar transistor.
http://ea1abz.ure.es/XTAL.jpg This is the beaufitul 4 MHz signal as received in the K3: http://ea1abz.ure.es/xtal.png As I do not have attenuatores nor combiners at the moment, the ugly setup is: http://ea1abz.ure.es/DDSandXTAL.jpg 50 cm wire conected at K3 antenna input. 4 MHz Xtal oscillador placed near the K3 wire antenna to produce a 9+20 signal. DDS generator tuned 10 Hz over the Xtal frequency, same level as Xtal signal. Here is the graph AGC-OFF, AGC-S, AGC-F comparison. I reduced RF gain in AGC-OFF mode to keep two tone audio signals level at the same value. Aproximate measured 3rd order products, relative to one signal level is: AGC-F: -17 dB AGC-S: -23 dB AGC-OFF: -45 dB. http://ea1abz.ure.es/AGC-off_AGC-S_AGC-F.png Let me know what do you think. This it what I can do with this poor setup. In the future, I plan to build attenuators and hybrid combiner to make a better test. 73, Ramiro. EA4NZ ______________________________________________________________ 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
