[Elecraft] Mildly confused - Assumed filter width and what I see in waterfall do not match

[Don Wilhelm]

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.

73,
Don W3FPR

Thomas Bingenheimer wrote:
> This is the current state of the radio :
> the 6 khz filter is in FL2, the 2.7 khz filter is in FL3. ESSB is on, and set to 4.0, complete with the '+' displaying in the right of the display when USB/LSB is used (note that it is off during DATA modes). AM TX is set to FL2,  SSB TX is set to FL3 (it will not allow it to be set to FL2, even with ESSB on). IN data A, I am setting the DSP to 4 khz. If the firmware is enforcing the use of FL3 for Data A, why would this be so? With software that can do 4.0 khz or greater waterfalls, why would we want to arbitrarily restrict the radio? For that matter, why restrict it at all for DATA modes? If the software on the computer would do it, why should we not be able to receive or transmit with say, the FM filter? If there is any such restriction, I would like to have the possibility of removing it considered. Thanks!
>   
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