Doug, >From a European perspective, and this is a personal opinion, while the 3rd Order dynamic range performance at 2kHz is certainly very important, it is the Spurious Free 3rd Order dynamic range at spacings less than the IF bandwidth that really matters, i.e. both test signals INSIDE the IF passband. Over here, working a weak DX station on say 40m, who is operating "No-Split" and who is covered by non-stop callers with strong signals, does require good in-passband performance to help the filter between the ears. Tx phase noise and clicks have been secondary issues.
It is an unfortunate fact that while receiver A's IMDDR3 performance might be quoted as being better than receiver B's at 2kHz spacing (outside of the passband), receiver B might be the better performer at spacings inside the passband, and more useful, because it has a better IF design than A's. The problem of course is that the reviews seldom include in-passband IMDDR3 performance, thus do not expose poor/ lousy IF systems. I understand that the present bar for in-passband Spurious Free 3rd Order dynamic range is 120db, set in 2007, but not on the market. 73, Geoff GM4ESD DOUGLAS ZWIEBEL wrote on Tuesday, June 16, 2009 6:58 PM > Yeah...at what spacing? > >>From the ARRL pages, for the IC7800 (I don't think anyone is saying >> teh 7600 is better than the 7800, but I could be wrong) > > At 2kc, 3rd order dynamic range for 7800 =86 db; for the K3=103db > > At 2kc, 3rd order intercept for 7800 = 21 dbm; for the K3=28dbm > > At 20kc spacing, things may change (I didn't bother to look), but who > cares...if the band is dead (few signals), these numbers won't matter > anyway. If the band is hopping (crowded), 20kc spacking specs are > meaningless (to me)....it's the nearby signals that will get your > front end. > > de Doug KR2Q ______________________________________________________________ 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
