[Elecraft] Xtal Filters

[Evert Bakker (PA2KW)]

Thanks Knut, Lyle, Don, Steve and Bill,

It must have become clear that I'm a CW operator and was used to SHIFT/WIDTH
already :-). SSB, different mind set eh....
I will check the "hiss" item and learn more.

Thanks for support and info!

73's, Evert PA2KW

BTW, a vary happy K3 user!
It's the first radio (I had) that beats the beast (TR7A/R7A). 

 

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of ab2tc
Sent: Thursday, May 22, 2008 00:35
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Xtal Filters


Hi,

I am assuming that you are using SSB. For SSB, use the Hi Cut / Lo cut mode
instead and adjust the Hi Cut for lower bandwidth. The Shift / Width mode is
not suitable for SSB since it wants to keep the center frequency constant,
while what you want in almost all cases is simply decreasing the high end of
the passband, keeping the low cut at 300Hz or so. SSB with a low cut of
600Hz sounds extremely bad. For the same reason, I find the XFIL button
unsuitable in SSB mode since it wants to "center" the new filter which again
causes the low cut to be way to high. I still think some of the design
choices for this rig are not optimal for SSB operators.

Knut - AB2TC


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
> 
>  
> 
> Any suggestion?
> 
>  
> 
> 73's, Evert PA2KW
> 
>  
> 
>  
> 
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