Joe, Understood. I wanted to be able to simultaneously hear and see 12 Khz or so of cw signals, thinking that I could more quickly identify the station being worked. For example, if I know the dx station is listening from 14.010 to 14.020 (admittedly pretty wide), I figured I could include that entire range within the FM filter bandwidth (which I still can do), AND also hear all 10 KHz of those signals (which I've learned I cannot do). Oh well; the FM filter will still let me hear a wider swath of the pile-up than my present 2.8KHz filter will...
73, Dale WA8SRA On 9/26/2012 9:25 PM, Joe Subich, W4TV wrote: >> The only reason I had for putting the FM filter in the 2nd receiver >> was to be able to hear more of the split in a broad pileup situation >> (like the extremely large split widths that we saw a few months ago >> with 7O6T), > The width of the roofing filter has nothing at all to do with hearing > more of the pile-up (unless you're talking about literally "listening" > to all the signals at one time like a pile-up tape). The P3's pick- > up point is ahead of any roofing filter - it can "see" up to 200 KHz > at a time. The K3 transmitter and receiver can be split anywhere in > the band and if the KRX3 is used with a separate antenna the K3 and > KRX3 can literally transmit on one band and listen on another. > > 73, > > ... Joe, W4TV > > > On 9/26/2012 8:58 PM, Dale Boresz wrote: >> Joe, >> >> Good observations, all. I agree that 4.2 KHz is certainly good enough >> for communications audio. >> >> The only reason I had for putting the FM filter in the 2nd receiver was >> to be able to hear more of the split in a broad pileup situation (like >> the extremely large split widths that we saw a few months ago with >> 7O6T), figuring that being able to simultaneously hear the wider >> bandwidth and see it on the P3 would be a great combination. I'll just >> have to be a bit quicker with the VFO-B knob ;-) >> >> 73, Dale >> WA8SRA >> >> >> On 9/26/2012 8:10 PM, Joe Subich, W4TV wrote: >>> The limit occurs several places ... adjust the "HI" setting and one >>> will find 4.20 is the maximum available. There is also an analog >>> lowpass filter in the audio (headphone and speaker) between the DAC >>> and the headphone/speaker amplifiers. >>> >>> I'm sure this limitation derives from the roughly 10 KHz clock/sample >>> rate used for the DAC ... Nyquist says the maximum frequency can not >>> be more than half the sample (clock) rate. 4.2 KHz is plenty good >>> enough for communications audio ... and not bad for AM with fading, >>> noise, and interference typical of medium and high frequencies. >>> >>> The FM filter still provides noticeably better double sideband AM >>> response (4.2 - 4.5 KHz with DSP/LPF skirts) than the AM filter >>> (3.0-3.3 KHz depending on the IF filter response). >>> >>> 73, >>> >>> ... Joe, W4TV >>> >>> >>> On 9/26/2012 7:23 PM, Don Wilhelm wrote: >>>> Sorry, but yes, the K3 audio is limited at 4 kHz, no matter whether it >>>> is to the headphones or to the speaker. Please do not "shoot the >>>> messenger". but that information is in the archives of this reflector in >>>> several places - it has been discussed periodically. >>>> >>>> If you want to lobby for extended audio response, that is fine, but I am >>>> just saying what the limits are today. Whether those can be extended or >>>> not is for the DSP designer to answer. >>>> >>>> 73, >>>> Don W3FPR >>>> >>>> On 9/26/2012 7:11 PM, Dale Boresz wrote: >>>>> On 9/26/2012 1:35 PM, Edward R Cole wrote: >>>>>> ... But I learned that audio is limited to 4-KHz >>>>>> regardless of IF filter so I ended up selling the extra 13-KHz filter. >>>>>> >>>>>> ... >>>>>> >>>>>> 73, Ed - KL7UW >>>>> I really hope that this does not apply to received audio to the >>>>> headphones or loudspeaker! I just purchased two FM filters (one for >>>>> sub-receiver to monitor wide splits) specifically to open up the receive >>>>> passband (audio included) for SWL and BCB reception. I have no intention >>>>> of actually transmitting FM or AM for that matter -- just want the wider >>>>> audio bandwidth for receive. >>>>> >>>>> So... is the received audio bandwidth *really* limited to 4 KHz? >>>>> >>>> ______________________________________________________________ >>>> 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 >>> >> ______________________________________________________________ >> 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 > ______________________________________________________________ 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
