[Elecraft] Problems because of filter switch during CW operation K2

[Tom Hammond]

Hello Martin:


>yesterday evening I was running into a problem during CW operation with
>the K2. I called CQ using the 1.5 KHz CW filter on 20m and got response 
>from a couple of US stations.
>
>The signals have been quite weak ( RST 33 ), but I have managed to copy
>a call sign and to give answer.
>
>Because of sudden QRM I switched to the 700 Hz filter but lost the
>signal. I have had big difficulties to "find" the signal of the US station 
>within the 700 Hz filter. So I switched back to the 1.5 KHz filter and 
>lived with the QRM.
>
>How can I align the CW filtes, so that I can switch to the narrow CW
>filters without losing the signal?
>
>By the way: It was very impressive again, how powerful CW is under
>difficult conditions!

The answer to your problem is that at least one, and possibly more) of your 
BFO settings for the CW NOR (or CW REV, whichever you were using) setting 
on your K2 have been adjusted to the WRONG SIDE of the filter passband.

Assuming that you are set to 40M, and have selected CW NORmal, ALL of your 
BFO settings should be BELOW the center frequency of the filter. And ALL of 
your CW REV BFO settings should be ABOVE the center frequency of the filter.

I would suggest you consider downloading Spectrogram v5.1.7 AND the 
accompanying K2 filter alignment documents from my web site at

    www.n0ss.net

and using Spectrogram to perform another CAL FIL session on your K2. The 
documentation describes how to determine the center frequency of your 
filter and how to use Spectrogram to perform the CAL FIL alignment.

73,

Tom Hammond   N0SS