> I would like to at least get the 4.2 khz mentioned - but in > fact, I do not.
I don't know why you can't get 4 KHz if you have a 6 KHz roofing filter enabled for receive in the DATA modes. I see 200 Hz to 4200 Hz with my audio spectrum analyzer software on the Line Out port (although the Line Out has more low frequency roll off than I would like between 200 Hz and 500 Hz). Set BW (WIDTH) = 4.00 and FC (SHIFT) = 2.20 and you should have 200 - 4200 Hz available to your waterfall. I have it with my FM filter (even when I tell the K3 configuration the FM filter is 6 KHz wide). In the direct e-mail, I've attached a waterfall that shows two CW signals (can't hear any PSK31 tonight) one at 1 KHZ and the other at 4 KHz with several weaker signals in between. You can also see the significant roll-off in the K3 Line Out response (-26 dB from 800 Hz to 100 Hz) below 500 Hz. 73, ... Joe, W4TV > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Thomas > Bingenheimer > Sent: Wednesday, January 07, 2009 11:01 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] Mildly confused - Assumed filter > width and what Iseein waterfall do not match > > > I would like to at least get the 4.2 khz mentioned - but in > fact, I do not. My chief concern is that I should at least be > able to use the full 4 khz waterfall that I can, in fact, get > out of most other radios. > > > --- On Wed, 1/7/09, Joe Subich, W4TV <li...@subich.com> wrote: > > > From: Joe Subich, W4TV <li...@subich.com> > > Subject: RE: [Elecraft] Mildly confused - Assumed filter width and > > what Isee in waterfall do not match > > To: t...@yahoo.com, elecraft@mailman.qth.net, "'Bob > Cunnings'" <bob.cunni...@gmail.com> > > Date: Wednesday, January 7, 2009, 10:15 PM > > > I guess my basic answer, is that should be my choice, > > not the > > > radio firmware. If I want to run 4 (or say, 10khz) > > into my > > > computer (and out) that should be my choice. > > > > The K3 does not support an audio bandwidth higher than 4.2 KHz > > in ANY MODE. If you do some checking you will find the > > DSP's > > digital to analog converter effectively includes a 4.2 KHz > > "brickwall" filter ... even in AM mode with the > > "bandwidth" > > set to 5 KHz (10 KHz IF). > > > > If you expect audio response above 4.2 KHz, you will need > > to > > convince Wayne and Lyle to relax the upper frequency limit. > > > > HOWEVER, for digital modes I'm not so sure that is a > > good > > idea. With sound cards sampling at 11025 Hz, the input > > audio > > needs to be band limited to 5.5 KHz maximum and 4.5 KHz > > offers > > a fair margin for safety to handle the occasional > > application > > that runs at 8 or 9 KHz. > > > > For AM - since the digital modes are not a consideration - > > it > > would be nice to have 5.5 or 6.0 KHz response. > > > > 73, > > > > ... Joe, W4TV > > > > > > > > > -----Original Message----- > > > From: elecraft-boun...@mailman.qth.net > > > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of > > Thomas > > > Bingenheimer > > > Sent: Wednesday, January 07, 2009 9:07 PM > > > To: elecraft@mailman.qth.net; Bob Cunnings > > > Subject: Re: [Elecraft] Mildly confused - Assumed > > filter > > > width and what Isee in waterfall do not match > > > > > > > > > I guess my basic answer, is that should be my choice, > > not the > > > radio firmware. If I want to run 4 (or say, 10khz) > > into my > > > computer (and out) that should be my choice. After > > all, how > > > is an SDR all that different. Again, I suspect this is > > a > > > oversight in the firmware, not a design choice. Why > > should > > > such a flexible radio be hobbled in this manner? > > (assuming, > > > of course, that it is actually limited as such, as > > opposed to > > > me setting it up wrong :) ). > > > > > > > > > --- On Wed, 1/7/09, Bob Cunnings > > <bob.cunni...@gmail.com> wrote: > > > > > > > From: Bob Cunnings <bob.cunni...@gmail.com> > > > > Subject: Re: [Elecraft] Mildly confused - Assumed > > filter width and > > > > what I see in waterfall do not match > > > > To: elecraft@mailman.qth.net > > > > Date: Wednesday, January 7, 2009, 8:59 PM > > > > Disabling the AGC in the K3 certainly does > > "do the > > > > trick" in terms of > > > > preventing strong signals in the passband from > > reducing > > > > receiver gain > > > > and thus affecting the weaker signal I'm > > decoding - > > > > that's exactly why > > > > I do it. > > > > > > > > As for ADC overload -that's a risk I'm > > well aware > > > > of but most of the > > > > time it's a non-issue, for me at least. If it > > happened > > > > I would react > > > > to it, but I rarely encounter signals in the > > passband at > > > anywhere near > > > > the level to cause trouble of that sort. > > > > > > > > Bob NW8L > > > > > > > > On Wed, Jan 7, 2009 at 6:23 PM, Don Wilhelm > > <w3...@embarqmail.com> > > > > wrote: > > > > > Bob, > > > > > > > > > > That will do the trick in an analog only > > receiver, but > > > > a receiver like the > > > > > K3 has an analog front end followed by an > > ADC and DSP > > > > processor. The trick > > > > > is to keep from overloading the ADC - should > > that > > > > happen, the copy will be > > > > > garbage. > > > > > > > > > > That situation is not limited to the K3 - > > overload of > > > > the soundcard ADC is > > > > > also a possibility with equally bad results. > > > > > > > > > > I have to admit that in many cases, one can > > operate > > > > with a wide bandwidth > > > > > with no problem, but when that strong signal > > enters > > > > the passband, the wide > > > > > bandwidth possibilities are "all > > over". I > > > > chose to take preventive measures > > > > > before that happens. > > > > > > > > > > 73, > > > > > Don W3FPR > > > > > > > > > > Bob Cunnings wrote: > > > > >> > > > > >> I simply disable AGC when I wish to run > > a wide > > > > receive bandwith with > > > > >> PSK31 for "point and click" > > tuning - > > > > precisely to avoid such a > > > > >> problem. > > > > >> > > > > >> Bob NW8L > > > > >> > > > > >> On Wed, Jan 7, 2009 at 5:44 PM, Don > > Wilhelm > > > > <w3...@embarqmail.com> wrote: > > > > >> > > > > >>> > > > > >>> Thomas, > > > > >>> > > > > >>> I will not answer your questions > > directly, > > > > >>> BUT > > > > >>> From an operational standpoint, > > using a wide > > > > bandwidth for data modes > > > > >>> is *not* the best way to do it. > > > > >>> The reason is AGC in the radio. Any > > signal in > > > > the receiver passband can > > > > >>> activate the AGC - and that is fine > > *if and > > > > only if* the strongest > > > > >>> station in the receiver passband is > > the one > > > > you are working - usually > > > > >>> that is not the case. The strong > > signal will > > > > reduce the receiver gain > > > > >>> due to its AGC action and the > > station you are > > > > trying to QSO with will be > > > > >>> reduced along with it. Overload of > > the DAC by > > > > the strong signals is > > > > >>> another similar consideration - > > fortunately, > > > > the K3 employs a hardware > > > > >>> AGC ahead of the DAC to avoid just > > that > > > > possibility. The DSP ADC can > > > > >>> handle an S9+20 signal without > > overload, but > > > > there are signals stronger > > > > >>> than that even in the sub-bands > > commonly used > > > > for digital. > > > > >>> > > > > >>> Using a narrow passband for data > > modes allows > > > > one to avoid that > > > > >>> situation. Yes, one must tune with > > the VFO to > > > > place the desired station > > > > >>> inside the receiver passband, but > > the > > > > possibility of a QRM free QSO is > > > > >>> much greater with the narrow > > passband. > > > > >>> > > > > >>> Just because the software > > application can > > > > display a 4 kHz slice of the > > > > >>> spectrum is not sufficient reason to > > use a > > > > wide receiver passband IMHO. > > > > >>> > > > > >>> Elecraft may well consider it just > > because > > > > some folks want to operate > > > > >>> that way, but it certainly does not > > make much > > > > sense to me. > > > > >>> > > > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > 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 _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
