[Elecraft] Xtal Filters

[Don Wilhelm]

Evert,

When using SSB, it is usually easier and better to use the HI CUT/LO CUT 
rather than width and shift.  Just reducing the HI CUT will usually 
result in a narrowed bandwidth but maintains intelligibility.
The BFO/Filter relationship should be preserved with the low end between 
250 and 300 Hz for best intelligibility with a narrow SSB filter - using 
Hi Cut allows you to easily achieve that.  You might want to tweak the 
Lo Cut setting a slight amount, but the bandwidth reduction for a SSB 
signal should be mostly from the high frequency end.

73,
Don W3FPR

Evert Bakker (PA2KW) wrote:
> Hello all,
>
>  
>
> Today I received the 1.8 Kc 8 pole filter and installed it tonight.
>
> I did the configuration with the software tool used for firmware updates as
> well (also performed an update as well).
>
> All went OK, but I do have a feeling something is wrong or my ears/brains
> work a little different from the majority (yeh yeh I know...)
>
> When XFil 2.7 is selected together with the DSP at 2.7 Kc, the audio sounds
> great. When decreasing the BW with the DSP to 1.8 (but keeping the centre
> the same), the hardware filter is switched in at 1.8 Kc DSP setting. During
> the decreasing process I'm loosing "information" (Ofcourse!) but my feeling
> says too much. When during the decreasing process I also lower the centre
> freq, the excessive loss of "information" is compensated. This gives me the
> feeling as if the filter isn't centered anymore.
>
> First I thought this might have to do something with the Offset (-0.91 for a
> 2.7 5 pole filter) but nothing was written on the 1.8 Kc 8 pole filter. I
> just tried it, but that didn't compensate the excessive loss.
>
>  
>
> During a process of decreasing bandwidth while listening to an SSB signal, I
> would appreciate if a shift of the centre-freq of the DSP is not required
>   
>