I originally chose the 8-pole filters thinking the steeper skirts would be useful should I ever take the radio into a dense RF environment like it is in the lower-48 states. MY experience with CW indicated 400-Hz was adequate as I could narrow this down with the DSP filter. I chose the 2.8 KHz SSB filter and 13-KHz filter for FM use with a VHF transverter.
One note is that changing filters on the main board requires removal of the sub-Rx so probably good to figure out what you want from the beginning. I installed a 2.8 and 13 KHz filter in my sub-Rx, thinking I could get the full bandwidth in audio to use with soundcards for SDR sw. But I learned that audio is limited to 4-KHz regardless of IF filter so I ended up selling the extra 13-KHz filter. I have thought of adding a 1.8 or 2.1 KHz filter for working tough SSB signals. I do try running the DSP down to that bandwidth but find that the DSP audio distortion sometimes is counterproductive to hearing weak SSB. I do not have trouble with dense local QRM up here in Alaska. I wonder if the roofing filters are easier to listen thru than the DSP filter? I did not install a second 400-Hz filter in the sub-Rx and that may be an error when I start running dual-pol diversity reception for CW-eme. At present, I only run diversity Rx in USB since I am running JT-65 on 2m-eme. I am testing a new program called MAP65 which maps and decodes all JT65 signals in a 90-KHz window. This covers 144.090-144.170 digital eme sub-band, nicely. Someday it would be interesting to set up a crossed dipole on 20, 15 , or 10m and listen in diversity Rx. Crossed horizontal dipoles actually sample different polarities of refracted HF. According to KL7AJ all HF is converted to circular polarity upon refraction in the ionosphere (see the recent article in QST by him). 73, Ed - KL7UW ______________________________________________________________ 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
