Dave, 1.
I prefer the 2.1 filter for SSB, 1.8 can potentially give a slight edge when the bands are extremely crowded, but generally speaking I use the 2.7 and narrow down to 2.1 if there is much QRM, remember that with the DSP you can go as low as you want, so it only makes a real difference if the interfering signal is way stronger than the one you want to copy. So in the end I swapped my 1.8kHz filter for an extra 500Hz filter for the sub receiver. 2. I haven't tried the 2.8kHz 8-pole filter, it has sharper edges than the 2.7k one and some people prefer it. I have the 6kHz 8-pole filter as well (for ESSB/SWL broadcast listening) and if the transmitting station is using a wide TX filter for SSB it sounds better with that in. Again, the DSP does a lot of the work so I don't think there is that much difference between the 2.7 and 2.8 filters, if I was to buy a new rig I'd probably opt for the 2.8 one, but not a strong preference. I think the main difference is slightly sharper edges on TX, and negligible on RX. 3. I have found the 400Hz filter perfectly adequate for CW and digimodes. A 1kHz filter would be much more useful, and I will probably get it eventually, but the 250Hz filter doesn't seem that useful to me. 400Hz gives enough of a context to make a weak CW signal stand out particularly when APF filter is on. For digimodes, I've copied a few PSK31 signals that I could not copy with >400Hz because it was drowned out by a very strong signal elsewhere in the passband, but I've never had this happen with a signal that was less than 400Hz away, remember you can adjust the width and center frequency independently and the K3 chooses the best crystal filter for the job, so you can move the rx window left or right to avoid any interfering strong signal close to the one you want to copy. All in all I'm very satisfied with my filter lineup which is: Main RX: FL1 - None yet (KFL3B-FM 13kHz FM filter on order, for operating FM on 10m and with transverters in the future) FL2 - KFL3A-6K (for AM/ESSB receive (and rarely used ESSB TX)) FL3 - 2.7kHz 5-pole filter FL4 - KFL3A-2.1 (for SSB and digimodes) FL5 - KFL3A-400 (for CW and digimodes) Sub RX: FL1 - None FL2 - None FL3 - 2.7kHz 5-pole filter FL4 - None FL5 - KFL3A-400 I wish I had room for 1 more filter, so I could have the 1kHz filter for use with wider digimodes and a wider PSK31 passband. Most of the time for PSK31 it is not necessary to go down to the 400Hz filter to copy the weakest signals, but 1kHz would be better when the bands are crowded. I don't think a 250 or 200Hz would confer any real advantage. 73, Thomas M0TRN On 27 March 2012 01:48, Dave (K7DRT) <dtull...@earthlink.net> wrote: > I am still studying the K3 and the various options I use. I still plan to > purchase one. > > My previous radios (IC-756PRO the last one) I used 2.4 khz and 1.8 kHz > for SSB and 500 hz & 250 hz for CW / Data. > > The K3 comes with a 2.7 kHz 5-pole filter. > > My SSB questions are: from your experience, 1) which is better for a > narrow filter for SSB; 2.1 khz or 1.8 kHz? > 2) Which is more useful, 2.7 kHz 5-pole or 2.8 kHz 8-pole? > > My Data question: Is the 400 kHz 8-pole adequate or should I purchase an > additional (250 hz or 200 hz) filter? > > Thanks & 73 de Dave K7DRT > > P.S. I did read the “K3 Crystal 'Roofing' Filters” It was very helpful. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
