Its my understanding that they are not great other than they do have steep skirts.
The R390 used IF transformers (tuned circuits) while the R390A had mechanical filters. The R390 was judged to work better, and the R390A was actually designed to reduce cost through the use of the mechanical filters. Although it is meaningless in an 8 MHz IF radio, I think at 50, 100, 262, or 455 KHz, tuned circuits may be best, but you likely need to design the circuit parts very carefully, and they might take up a lot of space, and be hard to adjust. Brett N2DTS > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of David Cutter > Sent: Monday, May 07, 2007 1:43 PM > To: Elecraft > Subject: [Elecraft] OT mechanical v crystal filters OT > > Off Topic but with so much expertise flying around I thought > I would ask how mechanical filters compare with crystal filters. > > I think they were fairly low in frequency (455kHz?), so, not > suitable in the present discussion, but it would be good for > our education at least. > > David > G3UNA > _______________________________________________ > Elecraft mailing list > Post to: [email protected] > 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: [email protected] 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
