[Elecraft] K2DSP puzzle

[Brendan Minish]

Yesterday I received my K2DSP and so far I am very impressed indeed with 
it's filtering prowess however there is one little thing that is annoying me.

When keying on a noisy band or when calling in a pile up the leading 
character element sometimes starts with a a pop in the side tone, as a 
sound engineer I am pretty fussy about how things sound and I decided to 
take a look on the scope and see why the K2DSP sounded different to the 
K2AF in this area.

This is what I found.
With the K2 Audio filter the RX audio is reduced to nothing over a few 
cycles about 22 mSec before the side tone starts up.
However with the K2DSP installed the RX audio gets turned off abruptly by 
the mute circuit about 16mSec before the side tone , when this happens near 
the top or the bottom of a cycle we get a pop.

I presume that the shaping of the RX audio as the K2 goes into transmit is 
done by the K2 changing over to transmit, the shaping when going back to 
receive is done by the mute circuit (change R17 on the Control board to 
adjust )

with the K2DSP installed there is a little extra delay inserted between the 
receiver and the filter output (processing time) resulting in the mute 
circuit sharpy cutting off the RX audio when going into transmit before the 
nice smooth transition has made it out of the DSP filter.

Since I generally like to operate Full break in with a quiet side tone the 
pop is pretty irritating at times.

has anyone else noticed this occasional pop since adding the K2DSP ?

Any ideas for a mod to fix this?
Slowing down the onset of the mute circuit slightly should do it but I am 
not sure how best to go about this.


73
Brendan EI6IZ