Thanks. That's almost as useful as if it would work. 73, doug
I want a lime-green (or black) Elecraft hoody. And a circular Elecraft slide rule. From: wayne burdick <n...@elecraft.com> Date: Fri, 23 Jan 2009 16:01:09 -0800 wayne burdick wrote: > Doug Faunt N6TQS +1-510-655-8604 wrote: > >> The question that came into my head late last night: >> Can I mix 8-pole filters for diversity reception? > > Yes. They all have equal offsets (0.00), so even though a different > filter may be selected on the two receivers at different bandwidths, > there will be no long-term phase drift. Doug, My apologies, but this actually will *not* work in all cases. In some modes, if the automatically-selected crystal filter is wider than will fit above the carrier (Fc), then the I.F., 1st LO, and BFO may all end up shifted to compensate. Thus the two sythesizers will not be on exactly the same frequency, and a phase offset is possible. Using your 400 and 250 Hz filters as an example: If your sidetone pitch were say 500 or 600 Hz and you had no passband SHIFT in effect, both synths would be set at the same frequency. But if you used a much lower sidetone pitch (say 300 Hz), the nominal position of the 400 Hz filter (but not the 250 Hz filter) might be shifted slightly upward, moving the synths apart, even though the perceived receive pitch is identical. This could produce a phase offset. So allow me to humbly retract my claim and suggest that all filters involved in diversity RX should, ideally, have matched bandwidths. In addition to eliminating phase offset in situations like I described, it will result in nearly identical close-in dynamic range performance for both receivers. Having a wide filter on just one of the receivers might leave it open to adjacent signals, detracting from the 'pure' experience of diversity mode that I'd like you to have ;) Thanks, Lyle (KK7P) for catching this. 73, Wayne --- 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
