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 <[email protected]> wrote: > From: Bob Cunnings <[email protected]> > Subject: Re: [Elecraft] Mildly confused - Assumed filter width and what I see > in waterfall do not match > To: [email protected] > 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 > <[email protected]> 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 > <[email protected]> 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: [email protected] > 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: [email protected] 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
