[Elecraft] Using CAL FIL and Spectrogram to set up the K2 filters

[Gareth - M5KVK]

Having finally got my KSB2 board working (it was a hi-resistance solder joint: enough to depress performance but not stop all signals), and calibrated the dial, I turned to setting up the filters.

I started with the filter widths and BFO settings in the KSB2 manual, but it didn't sound right. So I decided to use WWV and Spectrogram.

Now that I knew that the VFO was OK, I set it to 10000.00. No audio on LSB or USB, which is good.
I then tuned off by 600Hz to create a steady signal at 10000.60kHz (9999.40kHz on the other sideband) and displayed the audio on spectrogram with a 600Hz marker set.
I then went through CAL FIL, adjusting the BFO so that the audio tone was exactly 600Hz.

I did this on all modes and filter widths: except FL4 on LSB and USB, which I adjusted for a 1000Hz centre (so I can use them for PSK31).

I was surprised how far off the displayed spectrum was with the factory settings. On USB FL4, the centre was at 400Hz with the manual’s suggested BFO setting.

73, Gareth M5KVK