[Elecraft] K2 filter adjustment- frequency

[Tom Hammond]

Hi Mick:

>Just about finished building and got the first watts out of my K2.

Congratulations!

>However I need some advice please

Whoops...

>1.  If I tune to a carrier on F1 (ie filter position 1), at the same 
>pitch it is 1 KHz higher on F2,F3 and F4 (which are all the same) 
>Presume this is about BFO adjustment but can't see where to go. Any 
>advice please - apologies in advance as I think this is probably a 
>pretty simple mistake by me!.

When you find that one (or more) of your XFIL settings causes you to 
have to tune 'elsewhere' to 'find' the signal, this is almost always 
the result of having placed the BFO to the wrong side of the filter's 
center frequency (e.g. to the opposite sideband).

Assuming you are on 40M (or any band BELOW 15M), all of the BFO 
Freq./DAC values for CW Normal XFILs should be BELOW the recorded 
center freq. for the filter. For CW REVerse, all values should be 
ABOVE the filter center frequency. Note that as you narrow the 
bandwidth of the filter, the filter CENTER freq. will drop slightly, 
so it's always best to re-check to confirm exactly where the center 
freq. is when you switch to the next filter setting. However, the 
filter center will NOT change if merely switching between CW N and CW 
REV, just as the bandwidths change.

If you haven't considered doing so, you might want to try downloading 
a copy of Spectrogram v5.1.7 from my web site at www.n0ss.net (from 
the K2-Specific page), and also a copy of the XFIL alignment docs 
which appear just below the link to download Spectrogram (same page).

>2.  I find that tuning L1, L2 ,L3 and L4 is very broad - no very 
>obvious peak? Is that right? - receiver seems sensitive enough but a 
>bit low on gain using headphones (without preamp).

Without the PREAMP, you may find sensitivity a bit low on 20M and 
above. Generally sensitivity is more than adequate between 160M and 
30M without the preamp.

Cheers,

Tom Hammond   N0SS