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
