[Elecraft] No Sidetone on K2

[Unifiedtx@aol.com]

In anticipation of installing the KPA100 I have made the mod to use computer 
control via the KPA100's RS232 interface.  I cut the trace between Q5-gate 
and U6 pin 25 and placed a jumper between Q5-gate and U8 pin 4.  I also put 
the jumper between U6 pin 25 and P4 pin 1.  A .001 uF cap has been installed 
between P4 pins 1 and 5. (I have revision A Control Board which required 
these changes.  This is the mod that is on page 51 of the KPA100 manual)   I 
am currently using the KAT2 and the tuner is plugged into P4.  Page 25 of the 
K2 manual says "The sidetone is generated at pin 25of the microprocessor, 
while sidetone volume is set by the DAC using Q5 as a variable-drain-voltage 
saturated switch.  The DAC cannot be used to generate sidetone directly 
because the 60dB channel-to-channel isolation is not adequate to prevent 
slight modulation of the VBFO and BVIAS lines on transmit".  Is this RS232 
mod necessary when installing the KPA100?  I was under the impression that 
the KPA100 talks to the K2 via the RS232 line and that this mod was necessary 
for them to communicate.  Cutting the trace at U6 pin 25 I believe has killed 
my sidetone as I presently have it set up.  I would like any comments on this 
and whether this mod is necessary for the KPA100 installation.  Upon 
installing the KPA100 should the sidetone return?  Thanks.   Roy Morris  
W4WFB