When I had narrow filtering in my Omni V I found that S/N did not increase as bandwidth decreased. Instead, the noise began to sound like signal since both were at the same frequency. Add some filter ringing to the mix and sometimes the narrowest settings made copy worse.
As always, I reserve the right to change my mind as I get more operating time with various rigs :-) - Keith KD1E - -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Vic K2VCO Sent: Thursday, April 06, 2006 12:54 PM To: Elecraft Group Subject: Re: [Elecraft] KAF2 or KDSP2 for K2 #5287 Selectivity has two functions: to reject QRM and to increase the signal/noise ratio by narrowing the bandwidth. The crystal filter in the K2 is usually sufficient for QRM reduction, with the help of the "built-in wetware filter" in the human brain. However, it *is* advantageous to have the narrowest practical bandwidth when receiving a weak CW signal; the signal's energy is concentrated in a very narrow range of frequencies -- maybe 50 Hz is required for usual CW speeds -- while the noise is evenly distributed over the bandpass of the receiver. I find it useful to have a narrow audio filter available for this reason. _______________________________________________ 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
