Its true that most modern rigs have narrow filters for CW etc but most rigs use DSP in the final IF stage to do this. This narrow passband is not protected with narrow roofing filters. look at the FT950, AGC comes after the roofing filter and before the second and third IF. the narrowest option for the roofing filter is 3Khz and 20khz for the FT450 A strong signal outside the dsp passband but still within the passband of the roofing filter will still knock out the week signals no matter how hard you try. This holds true for many of the the rigs in the big three linup excluding some of the high end ones that most of us cant afford. one of the advantages of the K3 is its ability to use any roofing filter in any mode. making it awsome for digital. most of the other in its price range don't have this ability or even offer narrow roofing filters.
Not everyone can afford a K3 or FT5000mp I consider myself lucky to have a K3. before I had it I often just shut down as my older rig could not filter out that guy 400hz down bragging that he was running 200W psk to the guy that just gave him a 599 ++ report. yea it was 20 years old and wouldnt let me use the CW filter in ssb. It all boils down to the same thing. operate with consideration don't shout when you don't need to. you should operate the minimum power that is needed to maintain communications. > On 5/2/2012 1:07 PM, David Moes wrote: > > You are assuming that everyone has the luxury of narrow roofing > > filters and can filter out the week and reject unwanted strong > > signals. most PSK stations are not blessed with a K3 and are not able > > to suppress strong signals. before I had a K3 2.4 was the narrowes I > > could do. most afordable rigs today still stop at 3khz (FT950) and > > some even wider. > > That's not true. Every rig manufactured today provides a CW filter > option that works very well for reducing/controlling the AGC blocking > issue. The FT-950 provides selectivity down to 500 Hz in its "PKT" > modes as do many other "affordable" rigs. > > ______________________________________________________________ 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
