Hi Doug,
DOUGLAS ZWIEBEL wrote > > The roofing filters are used for reducing IMD. > 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 -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-use-of-1-8-filter-clarification-tp7187876p7187921.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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
