<<Why? If there's a single offending station, using the shift control with a 2.8Khz-8pole filter will be just as effective as with a 1.8Khz-8pole filter in minimizing the interference since the slopes are similarly steep.>>
I'm not a big fan of excessive shifting of passbands to clean up QRM. The problem is the change in passband would add other problems like noise that is lower pitched or, depending on the IF and selectivy system, even a little opposite sideband response. A narrower filter is always the better option performance-wise. The only debate is in cost vs. benefit. With passband tuning (IF shift) and narrow and wider filters, I find myself almost always using the narrower filter. Part of the reason is if the band is clear away from the offending station, it is easier to get everyone to turn the VFO dial. When there is no room to move a little, then it is very obvious there is QRM both above and below. For me it is a no-brainer. I always buy an assortment of filters for each mode that includes normal and "extra narrow". ______________________________________________________________ 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
