Jim, > He also says that "Re the bandwidth, a short time ago > Elecraft made a mod to the firmware so that audio bandwidth > and not IF bandwidth was displayed on the K3's screen. If > you're seeing 5KHz and you don't have FM filter installed > then it sounds like yet another bug."
This isn't a bug. The DSP bandwidth is simply wider than the IF filter. In practice the user will see audio out to 4 KHz or so at a reduced level following the filter skirts. > (2) What does the LCD BW actually read? > Is it an IF BW, an audio BW, or what, and does the displayed > BW actually corresond to reality? For wide modes the best way to display the bandwidth is LO/HI. Those are the numbers that correspond to the "real world." If you are looking at FC/BW, the BW number will be 2 * (HI-FC). Where FC is less than HI/2, BW will typically be overstated. In AM for example, "NORM" is BW=5.00 and FC=1.50. If you toggle to the LO/HI display you will find it showing LO=0.00 and HI=4.00. Most users would consider that to be BW=4.00. It is most convenient to consider that (other than in CW) the the audio DSP limits are FC<=2.20, HI<=4.20. 73, ... Joe, W4TV > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim Garland > Sent: Sunday, February 01, 2009 10:08 AM > To: elecraft@mailman.qth.net > Subject: [Elecraft] K3 AM reception > > > I've been reading a thread on another email reflector about > the K3's audio response on AM. One of the reflector > participants is a serious SWBC listener and is very > dissatisfied with his K3's AM audio. He has pointed out a few > things about the K3 AM response which puzzle me. Here they are: > > "My K3 sounds the same as others I've heard which I consider > to be absolutely terrible when using an external speaker and > beyond absolutely terrible when using the internal speaker! > The 6KHz roofing filter in the K3 will provide an audio > bandwidth of up to 3KHz and the FM 13KHz roofing filter will > enable the DSP to provide the user with an audio bandwidth of > approximately 4.5KHz I've been told by Elecraft." > > He also says that "Re the bandwidth, a short time ago > Elecraft made a mod to the firmware so that audio bandwidth > and not IF bandwidth was displayed on the K3's screen. If > you're seeing 5KHz and you don't have FM filter installed > then it sounds like yet another bug." > > His particular complaint is audio clicks on AM when hard > consonants (Ts, Ks, > etc) are spoken, a problem that he says has been confirmed by > other users. He has installed all the audio mods in his > radio, but they didn't fix the problem. > > This was all news to me. I've not used my K3 extensively on > AM, and maybe my ears aren't as sensitive as his, but I've > not noticed any problem. I have the 6 kHz roofing filter in > my radio, and the DSP BW goes up to 5 kHz, which he says is a > bug, and that the actual BW is only 3kHz. > > So my questions are: (1) Is audio distortion on AM a known > problem with the K3? (2) What does the LCD BW actually read? > Is it an IF BW, an audio BW, or what, and does the displayed > BW actually corresond to reality? > > Tnx, > > Jim W8ZR > > ______________________________________________________________ > 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 ______________________________________________________________ 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
