Don Wilhelm-4 wrote: > > The bandwidth can make a difference - the noise is broadband while the > signal is narrowband. > If the bandwidth of the receiver input is wide, then a preselector will > make a difference because it decreases the total noise that the receiver > is handling. > > Note that many(most) tuners will not produce that pre-selector effect. > Only those with a resonant circuit will do that. Most common T-network > of L-network tuners create either a high pass or a low pass filter. >
I still don't understand. If signals pass through a 500 Hz roofing filter on the front end of the rig, what effect can wideband noise have on the receiver? This assumes the noise is not strong enough to trigger the radio's hardware AGC, but wideband noise is typically far below that level (about S9+30). Unless the tuner has an extremely high-Q (i.e. like a crystal filter) I don't see how it can help a rig like the K3 with a CW roofing filter. Most tuners' bandwidths are in the order of hundreds of kHz...not hundreds of Hz. 73, Bill W4ZV -- View this message in context: http://elecraft.365791.n2.nabble.com/A-comment-about-Receiving-tp6216105p6219960.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
