I haven't looked at the spec for the 1.8 filter but I second what Dave was saying, the specified filter bandwidths are (I think) -3dB and the curve is obviously not completely straight down, so there is still signals outside the passband.
I have told my K3 that the 400Hz CW filters are really 500Hz, which means the 2.1kHz filter only kicks in when I move above 500Hz, which allows me a slightly wider passband e.g. when calling CQ, this works extremely well for me, and from looking at the waterfall the extra 50Hz on each side are getting through the filter well enough. I'm sure operating the 1.8kHz filter as a 2.1 one would work as well, although I never tried it myself, it might actually be a better setup than the 2.1 filter for contest use. 73, Thomas M0TRN On 27 March 2012 19:12, <[email protected]> wrote: > > > I am pretty sure the DSP filter is effective only if it is narrower than > the roofing filter. In your setup the DSP filter is pretty much turned > off. Please, don't forget, the crystal filters in K3 are ROOFING filters, > they are protecting next IF stages and the DSP from strong near by signals, > improving dynamic range . The main filtering is done in DSP. There is white > paper on the matter somewhere on Elecraft web site (by Eric S). > > > > 73, > > Igor, N1YX > > > > ----- Original Message ----- > > > From: "Dave Hachadorian" <[email protected]> > To: "Elecraft Reflector" <[email protected]> > Sent: Tuesday, March 27, 2012 12:52:51 PM > Subject: Re: [Elecraft] K3 Filter questions > > I used the 1.8 for the entire WPX SSB contest, with a DSP width > of 2.1 KHz. It sounded great. I never messed with any of the > settings for the entire contest. To get this combination of > DSP=2.1 and crystal=1.8, one has to install the 1.8 filter as if > it were a 2.1, so it switches in at DSP=2.1. This installation > setup is most easily done using the K3 Utility. In practice, > normalize, then use high cut until the filter switches in. To > me, the audio sounds best using that technique. WPX SSB is > traditionally the worst-case QRM-fest, and the 1.8 filter was > just the ticket for dealing with it. > > Dave Hachadorian, K6LL > Yuma, Arizona > > > >From experience, I had both the 2.1 and 1.8 fitted and by > >judicious use of > the Hi Cut/Lo Cut adjustment I find the 1.8 far better in > practice. > > ______________________________________________________________ > 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 > ______________________________________________________________ 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
