Hello all As David suggested we continue the discussion on the list. I have done some new poor man tests, using a local AM carrier on Medium Wave at 917 KHz. For generating the other tone, I am using the same home made DDS generator as before. At this lower frequencies the signal generated by the DDS is much more cleaner. The antenna is a 6.5m long dipole on the balcony and an open wire feeder as in the earlier tests, but using only one half of the dipole by just directly connecting one open wire end to the K3 antenna connector. The reasons of doing that is that my T match tunner does not work below 1.8 MHz. This eliminates the posibility of IMD products produced on the tuner toroids. It does not remove, just in case, other no-linearities found everywhere as suggested by (sorry for my poor english, I hope you understand me).
10 Hz spacing, ACG-F: http://ea1abz.ure.es/acg-F.png Now with AGC-S, notice the strong reduction of IMD: http://ea1abz.ure.es/agc-S.png Now see the AGS-S to AGC-S-soft transition on the middle of the capture: http://ea1abz.ure.es/agc-S_vs_agc-soft.png Now see the IMD at 100Hz spacing, AGC-F to AGC-S transition at the middle of the screen: http://ea1abz.ure.es/100Hz.png Sorry for the poor noise floor, is the Madrid band noise received by the antenna. Hi. I see that the IMD problem is worse with small carrier distances. At 100 Hz spacing they are much more weaker and not problematic. 73, Ramiro. EA4NZ ______________________________________________________________ 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
