I am hoping that Elecraft will have a different option for AM listening by the time that my K3 arrives (in April). A simple, lower-cost ceramic filter would be nice. Or, perhaps the roofing filter can be bypassed for AM listening. There are several receivers out there that have DSP-only selectivity for AM or SW listening. Or, at least, the audio BW will be opened up to 6kHz for AM listening.
I ordered the 6kHz filter thinking that I can use the entire 6kHz for AM listening. The process of amplitude modulation produces 2 sidebands and a carrier. Each sideband has the same information (one is a mirror-image of the other). If the highest modulating frequency is 5kHz, then the BW of each sideband will be 5kHz, and the total AM signal will have a BW of 10kHz. At the receiver, one of the sidebands is discarded, and the other is demodulated. So, a 6kHz filter should produce a nice sounding AM signal since a 5kHz-wide signal is passing through it. (I have heard some SW stations that must be using a wider bandwidth, based on how nice they sound on an old Hallicrafters radio. Radio China International comes to mind). Not to be able to have a 6kHz BW with a 6KHz filter is a surprising limitation (IMHO). 72, John W2XS -- View this message in context: http://www.nabble.com/New-K3-SN-207-built-but-question-on-AM-Filter-tp14780362p14804472.html Sent from the Elecraft mailing list archive at Nabble.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
