[Elecraft] Mods To The KSB2

[John Grebenkemper, KI6WX]

For the last 6 months I have worked on a set of changes to the KSB2 that
provide increased SSB performance for the K2.  These changes are not
required for the K2 to function well in the SSB mode, but are intended for
those who wish to obtain the best possible performance.  There are four
major changes discussed in the document.

The first allows the builder to select different SSB bandwidths for the KSB2
filter.  This may be especially useful if you desire a wider SSB filter.

The second improves the flatness of the 2nd Xtal Filter.  I had posted this
change to the reflector a few months ago and several people have implemented
it in their K2.  The change makes the LSB and USB response in receive nearly
identical.

The third change increases the RF gain of the KSB2 so that it will function
with lower output microphones without resorting to various resistor changes
that have been tried by a number of people.  It also allows the K2 to
achieve a slightly higher SSB output on 10 meters.

The fourth change reduces the in-band audio intermodulation distortion that
occurs in the KSB2 modulator by 15-20 dB.  This change is most important for
data modes, but should also increase the audio fidelity of the KSB2 in SSB
transmissions.

All of these changes are described in a document "Improving the Performance
of the KSB2" which may be downloaded from my website at
http://home.pacbell.net/johngreb/KI6WX.html

-John
 KI6WX