Keep in mind that the xtal "roofing" filters don't set the final bandwidth. They just protect the later stages of the K3 from really huge signals outside the roofing filter bandwidth. The "final" bandwidth is set by the DSP system in the second I.F. The DSP bandwidth is adjustable over a very wide range by turning a knob on the front of the K3.
You'll get a 2.7 kHz filter with the base K3 (at least the last I looked ;-). It's perfect for SSB and, frankly, I prefer it for SWLing AM on the HF bands to a 6 kHz filter and using the envelope (AM) detector. Receiving double-sideband, full carrier AM as an SSB signal removes all sorts of issues with AM on the short waves. Selective fading, where the carrier drops out causing serious distortion, or in which one sideband shifts in phase with respect to the other over the skip path are no longer a problem when listening in SSB mode. For really critical listening, especially to music, most prefer the 6 kHz filter and using AM mode (envelope detection). Bottom line, for SWLing, SSB and most Data and CW, the 2.7 kHz will do very well since you can crank down the DSP bandwidth as needed. Then you said you wanted an FM filter, so that's a given for the basic configuration. Next I'd suggest a 6 kHz filter for listening to AM stations in full double-sideband-full-carrier mode. And beyond that perhaps a narrower filter - 1 kHz or 500 Hz - to augment your digital/CW operations. They will be of significant benefit if you're using the K3 in a very dense signal environment where there are likely very strong signals inside the bandpass of the 2.7 KHz filter. Of course you can add filters at any time, even if you buy a factory-assembled K3. Full instructions are in your Owner's manual. If you don't have the KRX3 subreceiver, adding filters is 'hammer simple', taking only a few minutes after you pull the top and bottom covers. If you have the KRX3, you'll need to consider what filters you want to equip it with, keeping in mind it's receive-only. Adding filters then takes a little longer since there's more disassembly involved, but it's still a well documented and straightforward procedure to do in the field requiring nothing more than a screwdriver. Ron AC7AC -----Original Message----- Hi All I am seriously considering a K3 and would like some advice on configuration. My main interests, apart from the normal SSB HF and DX, are experimenting with the narrow bandwidth digital modes. 6m would also be a new band for me. Occasionally I like to listen to the "Short Wave" broadcast bands so will probably include the Gen Coverage Rx option. The K3/100 would be the base configuration together with the Internal ATU and I would probably include the Internal 2m module, which I understand also requires the KXV3A module. The real question is what filter configuration I should consider. The FM filter is probably a given. I am not really interested in AM transmissions but do I need the AM filter to listen to the AM broadcast bands? I wish to have a good CW capability (CW Skimmer has made me go back to developing these skills) but the priority would be the narrow band modes. I would appreciate any comments/advice. Deane VK1DW ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
