David, Some time ago I did a "numerical comparison" using the published -6dB and shape factor values. Perhaps these will help until the "official" lab results are published.
> 200 250 400 500 > ------------------------------------------------- > - 6dB 224 370 435 565 Hz > -60dB 896 777 913 1751 Hz > slope 6.22 3.77 4.43 10.98 Hz/dB > > -10dB 274 400 470 653 Hz > -20dB 398 475 559 873 Hz > -30dB 522 550 647 1092 Hz > -40dB 647 626 736 1312 Hz > -50dB 771 702 825 1531 Hz In my opinion, the 200/500 pair is the best value. That is reinforced by comments on IMD performance and receiver design by people like Rob Sherwood. The only reason to look at the 8-pole filters might be the need for a slightly wider "narrow" filter if you were into RTTY (I don't know if 224 Hz is too narrow for 170Hz shift RTTY - particularly with fading and/or multipath). For a died in the wool RTTY DXer, a steep sided 270 - 300 Hz filter would be nice instead of 370 Hz from the "250 Hz" filter. 73, ... Joe, W4TV > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of David Lankshear > Sent: Sunday, January 27, 2008 12:11 PM > To: elecraft@mailman.qth.net > Subject: [Elecraft] K3 filter performance > > > Sorry to ask this of the list, but there's been so much > comment on K3 filters, I seem to be going round in circles > trying to find where, if anywhere, evaluations have been done > on the 5-pole filters. I'm resigned to never getting my > detectve's badge, Sherlock. HI! > > Elecraft have (most of?) the 8-pole ones on the website but > I'd like to compare those details with similar tests done on > the 5-pole. > > Also, there has been mention of variable filters. As new > orders placed now are estimated for May shipping, perhaps the > varibles would be available by then, so is there any > technical information on them yet, please? > > 73 all. DaveL G3TJP > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
