[Elecraft] Hearing the effect of narrower roofing filter

[David Cutter]

But if you leave the setting at its nominal, can you hear the difference as 
that bandwidth is selected?  I'm not sure I understand the advantage you are 
gaining by bringing the crystal filter in later; I'll do if there's 
something to be gained, it sounds an interesting approach.

David
G3UNA


>A couple of related points, which may not be new news to anyone:
>
> You can set the K3's filter bandwidth configuration to cause the roofing
> filter to switch at points other than the bandwidth printed on the filter.
> Maybe you would like your (nominally) 500 Hz filter to switch in at 450 or
> 550 Hz.  My 8-pole 250 Hz filter is a bit broader than 250 Hz, and I've 
> set
> it to switch at 300 Hz.
>
> You can also turn off a filter (set its bandwidth to zero temporarily) to
> evaluate whether a change you're hearing is due to the roofing filter or 
> the
> change in bandwidth provided by the DSP.
>
> And you should attempt to adjust the filter gain compensation so that 
> there
> is no change in the volume of the note you're tuned to.  Rene, who guides
> the assembly of K3s built by Elecraft, told me that he uses a voltmeter on
> the speaker terminals when adjusting the gain compensation and can get
> usually get within a half decibel.
>
> I notice a definite qualitative change as the narrower filters switch in. 
> It
> sounds quieter, and it seems like the volume is being turned down. I think
> I'm responding to the reduced low and high frequency components that are
> supposed to be cut off.  The DSP-related changes seem more gradual.
>
> Dick, K6KR
>
>