Guy, K2AV said, The point of the roofing filter is to reject the VLS in the next slot above and below me.
Hmmm. This is not at all how I see the primary function of a roofing filter. What you describe sounds to me like the function of the final BW filtering. When I use a rig on 40m cw (since I'm also a contester on the east coast) that has a wide roofing filter (eg, 48 or 24kc), I hear IMD across the band (beeps, squeals, "corrupted" cw). Some of these "phantom" signals are louder than the weak guys I want to work and hence "cover them up." With the K3, utilizing a "narrow" roofing filter addresses the IMD problem. Even the 2.7kc filter is a pretty darn narrow roofing filter and I have yet hear IMD on 40m using it. Since I almost always use the 500hz roofer when I'm on 40m cw, I again have not had an IMD issue. That is not to say that when someone "moves in close" to the QRG of a weak guy, that I don't "hear the effect" of them being close...but narrowing the DSP filter a bit (which is functioning at both IF and AF in the K3) gets rid of them most of the time. If they are really close, adjusting the DSP down to 50hz does the trick 99.9% of the time. If the two signals are "on top of each other," well, nothing works. As for "pumping the AGC," you can always turn the AGC off and ride the RF gain. But it has been my experience that (a) either the loud guy who is close will move away (b) trying to fight such a situation (and trying to win) can cost you more points than it is worth. And if the other guy is THAT CLOSE and you are both running, then there is always some doubt as to which one of you the weak DX is actually answering (again, bad for the score). Just my observations...YMMV. de Doug KR2Q _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
