[Elecraft] K2 TX audio

[Don Wilhelm]

If you have the K2/100, remove the KI6WX mod - without the KPA100, it 
makes no difference.
Make certain the SSB FL1 filter is set to OP1.
Check the position of the OP1 filter passband with Spectrogram  . The 
low frequency 'knee' of the passband should be close to 300 Hz.

If you are wondering what I mean about the 'knee' of the passband, look 
at the top of the passband shape and then look to the left (low 
frequency end).  Find the place where the passband response is about 3 
dB less than the flat of the passband - that point is the 'knee' that 
you need to place close to 300 Hz.

Be aware that many VHFers want to hear very wideband audio but the K2 
cannot produce that. You should have good communications quality audio - 
test on HF.



73,
Don W3FPR

On 12/21/2021 5:24 PM, Geert Jan de Groot wrote:
> On 21/12/2021 21:30, elecraft-request at mailman.qth.net wrote:
>> The SSBCAPKT was released November 2004.??? KSB2 kits built before that
>> had a 2.1 khz filter.
>> Look at? your KSB2 board.? If CB and CN positions are populated, you
>> have the narrow 2.1 khz filter width.
>
> On my Rev-A K2, I've changed crystals, changed the filter capacitors 
> for 2.6kHz, and made the drive modifications from KI6WX (I'm driving 
> transverters on 10m).
>
> People complain that the audio doesn't sound right, and the 
> Spectrogram grapth is far from flat. I'm OK with RX audio but people 
> complain about my TX audio.
> Is there any way to make the passband flatter, or to make the audio 
> "fuller"?
>
> I am aware that TX and RX can use different filters and adjusted for 
> that. I just worry about the TX reports I am getting.
>
> Geert Jan
>
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