Bill, BTW, it happens also when switching from 400 to 2100 (both zero offset).
From the earlier explanation I remember that the side of the filter BW is placed on the side of a signal. (I donot know how to say it a better way). The filter is not placed symmatrically. So when changing the filter, and also when I change the shift, the CWskimmer display moves.. 73 Arie PA3A Op 23-2-2011 14:43, Bill W4ZV schreef: > > Arie Kleingeld PA3A-2 wrote: >> When using different roofing filters in the K3, the IF-offset changes a >> bit in the K3, if you switch to another roofing filter, if I understand >> it correctly.. It has been explained in this reflector that this happens >> for a reason. It has to do with the way the roofing filter is placed >> over the signal you are listening to. There are experts that can explain >> what happens exactly. (So some more info is needed please.) >> >> I was not aware of this problem untill I used CW skimmer and the N1MM >> logger bandmap and saw that I had to keep the 400 roofer in place >> otherwise the spots would be placed on the wrong freq in the bandmap. So >> that's what happened here. >> >> I wonder if others have seen this behaviour and what they did about it. >> > Your understanding is correct. Each time the K3 changes roofing filters, a > different offset is required for CW Skimmer to zero beat unless (the filters > have identical offsets). This is one good reason to select all 8-pole > filters since they have identical offsets of zero. Yes, before someone says > it, I know the 8-pole offsets are not actually zero but it doesn't matter > since the offsets are a small percentage of total bandwidth (even the "250" > which is actually 370. > > In contests I use both a 500 Hz Inrad 8-pole and a 200 Hz Elecraft 5-pole. > For the CQ 160 which is EXTREMELY crowded, I used the 200 Hz 99% of the time > (both for running and for S&P with Blind Skimmer) so I set Skimmer's offset > for the 200 Hz filter offset. In the ARRL DX, which is not so crowded, I > used the 500 Hz when running (when I don't need a waterfall) but then > adjusted WIDTH so the 200 Hz was activated when using Blind Skimmer to S&P > on the waterfall decoder dots. Since Skimmer's decoder dots are so accurate > in placing the K3 passband on signals of interest, the simplest thing to do > is to always use your narrowest filter setting for Skimmer. You could > quickly change this by making Filter Preset I for "normal" use and Preset II > for "Skimmer" use. > > Another thing I do is record the two different offsets for Skimmer (for the > 500 Hz and 200 Hz filters) and paste it above the appropriate place on my > monitor. Then I can quickly adjust Skimmer's Setting Menu if I ever need to > change the filter used with Skimmer. > > 73, Bill > ______________________________________________________________ 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
