IMHO, there are few folks in the contest world that are better technically than Bill (W4ZV), so I would suggest that everyone take his comments very seriously.
Bill...I do have a question or two, with respect to your statement below. 1. Just how often do you find that you run into a situation such as you describe below? I don't mean simply, "during every a contest," I mean more like how often during a contest? For how many Q's? 2. If the really close and really strong signal is pumping your AGC, why not just turn off the AGC and ride the RF? This is not a rhetorical question, because I know you do this. So I'd like to learn why you would, in some situations, prefer to not do that. I would love to learn a new trick! 3. And just out of curiosity (on SSB), how long would you tolerate being so close to someone who would pump your AGC? Of course, for me (QRP), the answer is zero seconds. :-) W4ZV said: I agree IMD reduction is not a big issue on SSB but blocking dynamic range (BDR) is the primary reason I sometimes need a narrower filter. If you have an S9+25 SSB signal CQing next to you (sometimes the case in crowded contests), a narrower filter will prevent it from de-sensing your receiver. If part of the interfering signal falls inside your 2.7k filter, signals on your frequency will be gain modulated by his signal (commonly called AGC pumping). In this case a narrower filter will prevent the problem. Of course when this happens, we still have to contend with his transmitted "splatter" (typical SSB TXs run -35 dB IMD which would result in ~S7 splatter from an S9+25 signal), but at least you can still copy signals at S7 or above (and lower when he's not transmitting). 73, Bill ______________________________________________________________ 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
