[Elecraft] K2 Speech Processor

[Sverre Holm]

> Has anyone tried the DF4ZS RF speech processor in a K2 yet?
>
I haven't tried anything like that myself. Since RF clipping is
considered to be the most effective form of speech processing for SSB, I
think it would be a valuable addition to a QRP K2 in particular. 

I have started to wonder if the KSB2 could be modified to include it.
One would have to break the path between the NE612 balanced modulator
and the SSB filter, and insert a new filter there followed by a clipper
taking proper care of gain and impedance matching. Diode switching could
be used to switch between the original path and the clipper. One could
even use the menu setting for microphone gain for the toggle, if as in
my case I always have it in the high gain setting anyway.

The new 4.915 MHz filter would have to have a flat passband equal to or
wider than the KSB2 filter, but doesn't need as high stopband
attenuation, only enough to attenuate the other sideband reasonably well
so that intermodulation products between the desired and the undesired
sidebands in the nonlinear clipping products don't become too prominent.

My question to the group is if such a filter is feasible, ideally using
a few (say 4) of the old 4.915 MHz crystals many of us have lying around
after performing the crystal substitution in our K2's.

--
73, 
Sverre

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Sverre Holm, LA3ZA
www.qsl.net/la3za