I'm not fond of SSB contests so I only ordered the 2.8 KHz filters for SSB when I bought my K3 (I do have the 250 Hz filters for CW). I had a change of heart at the last minute, though, and ordered two of the 1.5 KHz 8-pole filters from Inrad last Wednesday. They arrived in the mail Friday afternoon (2 days service with no request from me for special rush!!!) and I installed them that evening after 20m died. I ran the entire remainder of the contest with the DSP set to 1.4 KHz and the shift set for a center frequency of 1.00 Khz. I also used the AGC settings Don had posted with very good results. Depending upon the voice characteristics of the person on the other end, though, it is possible to crank the DSP bandwidth down to 1.0 KHz or lower (with an appropriate shift) and still be able to get intelligible copy.
Even so, the crud during the contest was incredible from adjacent stations, many of whom simply had horrible signals. It's pretty sad when S9+20 signals are so distorted that they almost cannot be copied. I swear some people must simply crank up the mic gain and compression until the output power stops increasing. I'm totally not an audiophile when it comes to contest intelligibility, but I'm always surprised at how many of the big stateside contest stations have really crummy signals. The South American contest stations seemed to be the worst by far, although there were some extremely clean signals from many of the single ops down there. And YN2NB (operated by N1SNB), who according to radio-sport.net seems poised to win World Single-Op High Power, had a terrific sounding signal. In any case, if the crud falls within the passband of whatever filter you're using, there isn't much of anything that's going to remove it. Painful as it can be, about the only thing I find that sometimes works is to temporarily crank up the audio high enough to let my brain sort out the weaker signal below the stronger spill-over distortion. I'm not sure 1.5 KHz filters give any better results than I would have gotten from the 1.8 KHz filters, but I didn't find any problem with them and I only planned to buy one set of narrow SSB filters anyway. If QRM and crud are bad enough that narrow DSP and a wider filter doesn't work, I'm going to go as narrow as I can. 73, Dave AB7E Ed Muns wrote: >> I noticed when I tried to narrow the passband from the 2.7 >> nominal that the signals often decreased in intelligibility. >> I used 1.8 K filters on my Yaesu FT 1K. I also notice I was >> not tuning dead on to SSB signals, I seemed to be off to the >> side emphasizing hi end response. I could hear as I swung >> past the station where the more dead on was. I haven't >> noticed that with other rigs. >> >> So I am asking: Would the 1.8 help, and still maintain good >> intelligibility? What other tweaks or changes have the list >> members used for top phone performance. >> > > I have been using a 1.5 kHz bandwidth on SSB with the K3 for over 18 months > now. In fact, I never use a wider bandwidth. I think the intelligibility > is excellent. The K3 has changed phone Sweepstakes from tortuous to > pleasant for me. Unlike CW where WIDTH and SHIFT are handy, I only use HI > CUT, and occasionally LO CUT, on SSB. To go from the default 2.8 kHz to 1.8 > kHz on SSB, simply reduce HI CUT by 1000 Hz. As I go further, I find that > around 1.6 kHz bandwidth, I like to increase LO CUT 50-100 Hz for optimum > intelligibility. The 1.8 kHz (actual -6 dB BW is 1.9 kHz) crystal filter is > an excellent roofer for this application. I use the narrower 1.5 kHz > crystal filter (actual -6 dB BW is 1.65 kHz), available from INRAD. > > Ed - W0YK > > ______________________________________________________________ > 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 > > ______________________________________________________________ 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
