[Elecraft] K2 power problem with FT8

[Don Wilhelm]

How old is this K2?  Those K2s with Serial Numbers below 2560 have the 
original IF crystals.  You will achieve a flatter passband if the 
crystals on the KSB2 board (and the RF Board) are replaced with the 
upgrades crystals.

If your KSB2 card is older, check the resistors on that board against 
the newer schematic to be certain the PSK mod has been added to that 
option board.

Make certain the filter alignment is done correctly and that the OP1 
filter is selected for the FL1 filter.

Do a complete filter alignment using a visual aid like an audio spectrum 
analyzer like Spectrogram running on your computer and a broadband noise 
source (like the Elecraft N-Gen) connected to the K2 antenna.  You can 
find Spectrogram on my website www.w3fpr.com - scroll down on the home 
page to near the end.

Don't overlook the possibility that your soundcard may not be producing 
a flat response.

73,
Don W3FPR

On 12/3/2019 3:22 AM, Markku Siipola wrote:
> I have started to use my K2 for FT8, with the KIO2 digital interface and 
> the SSB-module. My sound card is connected to the hear phone and 
> microfon connections. Software WSJT-X, JTAlert and DXLab commander.
> 
> On 80m and 40m all is ok, but not on the higher bands. For example on 20 
> m, the power is reduce very much for certain LF frequences. I tested 
> this by using the TUNE function in WSJT-X and changing the TX frequence.
>