[Elecraft] filter offsets question

[David F. Reed]

Ron (& Bruce, who also replied),

thanks so much for an understandable explanation.

73 de Dave, W5SV

On 2/19/12 5:46 PM, Ron D'Eau Claire wrote:
> David, there are both 5 pole and 8 pole filters available from Elecraft. The
> 8-pole filters have a somewhat flatter passband and steeper skirts than the
> 5-poles. (These are crystal filters and the "poles" refer to the crystal
> poles in each filter - more poles means better filtering but more complex
> matching of the crystal elements required for correct performance, hence
> greater cost).
>
> Because the specs on the 5-pole filters are a little looser their exact
> center frequency may shift slightly. The "offset" is a value entered to
> center up a 5-pole filter on the K3's intermediate frequency. The 8-pole
> filters are extremely consistent and need no offset correction.
>
> The "standard" 2.7 kHz filter is a 5-pole filter, hence a correction value
> is provided. The 2.1 KHz and 250 Hz filters are both 8-pole types and the
> "correction" is zero.
>
> 73,
>
> Ron AC7AC