Hi Jim, The K3 comes with very narrow ham-band filters, standard. These provide the excellent SWL rejection that you're referring to, which is especially important in a down-conversion superhet design. To obtain full SWL coverage, the K3 user can install the KBPF3 option, which adds wider filters that cover the entire range of 0.5-30 MHz. This has no impact on ham-band performance, as the wider filters are only switched in when you tune well outside the ham bands.
The KX3 has a different receiver architecture, similar to direct conversion but with quadrature channels (I/Q) to allow for single- signal reception. This architecture doesn't involve a large I.F., so there are fewer images to deal with in both RX and TX mode. This lightens the requirements for band-pass filtering. As a result, the KX3's band-pass filters can include ham and nearby SWL bands without any need for tuning. The K1, KX1, and K2 have tuned ham-band filters that provide coverage of most nearby SWL bands. 73, Wayne N6KR On Oct 23, 2011, at 9:58 AM, Jim Lowman wrote: > After almost 50 years of being a ham, I see that the conventional > wisdom > of NOT including general coverage in a receiver has been refuted. > It was > thought to be at the expense of performance on the ham bands. > > How have modern design techniques overcome this limitation? > > 73 de Jim - AD6CW > > On 10/22/2011 10:11 AM, Wayne Burdick wrote: >> Hi TR, >> >> The KX1 is our smallest radio, with TFR (trail-friendly) format and >> an >> attached paddle, like the KX3. It also uses a DDS VFO and SSB/AM >> receive, providing SWL coverage in addition to the ham bands. >> >> 73, >> Wayne >> N6KR >> >> >> > ______________________________________________________________ > 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 ______________________________________________________________ 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
