[Elecraft] Crystal Filter Offset in 4.81, What does it mean?

[Don Wilhelm]

Arnie,

Think about it this way -- take a filter width of 1500 Hz and a sidetone 
pitch of 600 Hz.
If you center the passband at 600 Hz, the upper passband limit will be 
at 1350 Hz, but the lower edge will be 150 Hz into the opposite sideband 
(single signal reception goes "bye-bye").

The proper position if the passband is to place the lower edge at about 
100 Hz, and the upper edge will extend to 1600 Hz.

That is true for any passband that is greater than 2 times the passband 
width.

73,
Don W3FPR

On 2/6/2014 10:14 AM, Arie Kleingeld PA3A wrote:
> Lyle,
>
> What are you saying here?
> The DSP filtering as a second IF would do (and I quote you) a 
> /terrible/ job. :-)
>
> 73,
> Arie PA3A
>
>
> Lyle Johnson schreef op 5-2-2014 16:35:
> <snip>
>> The "center of the passband to the nominal pitch value" only occurs 
>> at higher pitches and/or narrower passbands.
>>
>> Think about the case where you have 1.5 kHz width selected and a 
>> pitch of 500 Hz.  You defintely do NOT want the center of the filter 
>> and the pitch to be equal,or you'd have /_terrible _/opposite 
>> sideband suppression.
>>