[Elecraft] Possible K2 sidetone mod

[Don Wilhelm]

Duane,

That input to the LM380 chip is not the normal audio input (check the 
LM380 datasheet). The sidetone level is fixed by the menu parameters and 
is not variable with any knob.

73,
Don W3FPR

dw wrote:
> I don't have my K2 yet…but should have it in about a week..depending on
> options.
> I noticed in the schematic that the side-tone output(U10B pre-amp) looks
> to
> be connected as a secondary input to AF-amp(U9 LM380).
> This makes me assume that side-tone volume is not fixed, but instead
> changes along with, and is a percentage of AF volume.
> If that is true, its a setup that I don't prefer.
>
> My (off-the top of my head) solution would be to splice in a 2N3904 on
> the output of U10B, and then move that output over to
> AF-OUT.
>
> That way, I always have a fixed side-tone volume, no mater what the AF
> volume is set at.
>
> Has anyone else done something like this already?
>
> Thanks
> Duane
> N1BBR
>   
>