[Elecraft] K3 Filters and dual bandpass tuning

[Don Wilhelm]

Andrew,

The answer is yes to all of that, except for minor points related to 
your interpretation.
For clarification, there are two considerations - the first is the 
filter width.  That is not necessarily the roofing filter width, the DSP 
filter width can be much more narrow than the roofing filter.  Think of 
the roofing filter as something protecting the K3 demodulation from 
extremely strong signals, much as a house roof protects those things 
under it.  Yes, if you have multiple roofing filters installed, the K3 
will automatically switch them in as you change the DSP filter width.

The K3 DSP determines the ultimate filtering, rather than the roofing 
filter.

Once the DSP filter width is set,  that filter passband can be moved 
about to change the position of the passband within the demodulated 
audio range by changing SHIFT - this SHIFT is equivalent to Passband 
Tuning - it repositions the passband without changing the tone of the 
received signal..

73,
Don W3FPR

andrew vavra wrote:
> Question for the experienced K3 owners...
>
> I'm planning a purchase in the very near future and want a 
> clarification on the roofing filters and use of passband tuning with 
> the K3.
>
> I think I understand from reading the forum that the K3 automatically 
> selects the filter to match the width of the passband.  In other words 
> if I narrow the passband using the dual PBT to 500 Hz, the K3 will 
> select the 500 Hz roofing filter.
>
> Am I interpreting this correctly?
>
> If this is true, what if I only have 1 roofing filter in the rig... 
> say the 2.7 kHz?  Can the passband be narrowed even further using PBT 
> like I can do with my 756 Pro?
>
> Thanks in advance.
>
> Andy, KD3RF
>
>