[Elecraft] KX3 roofing filter query

[Don Wilhelm]

Chris,

The fault is in human ears and their perception of human speech.
There must be some content in the 300 to 600 Hz region to maintain 
intelligibility.
Using Hi-Cut only, you should be able to reduce the high end to about 
1500 Hz while still maintaining intelligible speech.
But if one tries to cut the low end much above 400 Hz, you lose 
intelligibility fast.

If you are using width/shift, you will have to reduce the width and then 
use shift to regain intelligibility.  IMHO, it is easier to use Hi-cut 
and just cut the high end while leaving the low end at 300 Hz.

73,
Don W3FPR

On 7/31/2013 5:24 AM, Chris Meagher wrote:
> Hi,  I have installed the optional roofing filter into my KX3 #4559.
>
> The manual advises that bandwidth switches to 3000Hz when Weaver
> demodulation is in use on SSB. However when I reduce the RX passband to
> 2.4KHz, which is when Weaver is supposed to kick in, it stays on FL1, until
> I reach 1.7KHz. At this point, FL2 is activated, however this is so narrow
> that it is close to unintelligible.
>
> Is this normal, or am I missing something?  Maybe using width/shift rather
> than Hi-lo cut doesn't activate Weaver? I would much appreciate some
> enlightenment as to how it all works, as I'm mainly interested in close in
> rejection, without having to discern which side the intrusion is coming
> from. Also I find anything below about 2KHz bandwidth too difficult to
> discern.
>
>