Maybe NL7Y is on to something here. From previous correspondence on the reflector, 60 dB BW of the DSP = 6 dB BW + ~300 Hz. So, if you have the DSP BW set at 150 Hz, the -60 dB point is about 450 Hz. I can't find plots of the 200 Hz filter, but I'll bet that the effects of that filter and the DSP are additive in this region.
Dave Hachadorian, K6LL Yuma, AZ ----- Original Message ----- From: "Vic K2VCO" <[email protected]> To: "Gary NL7Y" <[email protected]> Cc: <[email protected]> Sent: Monday, January 26, 2009 4:42 PM Subject: Re: [Elecraft] K3 in 160 contest > Gary NL7Y wrote: >> >> I've found that with the 200Hz filter enabled in both of >> my receivers via >> diversity reception mode, BW set to 150 or less, that >> weak sigs pop out of >> my high S5 city noise floor like the best audio APF >> enabled rigs I've owned >> (many). Elecraft has a Genie of sorts helping us on CW, >> and no filter >> ringing that I care to mention. > > Are you sure that the 200Hz filter had anything to do with > this? Maybe you would have had > the same results with a 400 or 500 Hz filter with the DSP > bandwidth at 150 or less. > > I've seen several comments like this, but keep this in > mind: with the DSP bandwidth set to > 150 Hz the only time you will notice a difference between > the 200 and 400 Hz filters is > when there is a S9+30db signal that is more than 100 and > less than 200 Hz away from the > desired signal. > > I made some simplifying assumptions in the above, but you > get the idea. > > Put another way, you would not notice any difference in > performance between a K3 with > *only* the supplied 2.7 kHz filter and one with a 200 Hz > filter unless there is a signal > loud enough to activate the hardware AGC (about S9+30dB) > which is within the filter > bandwidth but outside the DSP bandwidth. > > -- > 73, > Vic, K2VCO > Fresno CA > http://www.qsl.net/k2vco > _______________________________________________ > 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
