[Elecraft] No Sidetone on K2

[Tom Hammond NØSS]

Roy:

>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

If you have rev 2.0x of the K2 firmware, select the alternate sidetone 
output port:

Primary Secondary
ST L Sidetone level, *TONE pin

* Additional Edit-mode Options

   The following menu entries provide extended options
   in edit mode. These are selected by tapping DISPLAY
   once the specified menu item had been selected.

   STL Selects the sidetone source, U6-25 or U8-4.
   Use U8-4 with the KIO2 (see KIO2 manual)

73,

Tom Hammond   N0SS