From the PC-EVE BBS in Texas:

From: Walt Fair
  To: ALL
  Re: KDK FM-240 FOR PACKET

Anyone trying to use the KDK FM-240 for 2 meter Packet will probably find
that it doesn't work. Seems that there are 2 problems: 1) KDK set up the
PTT line to go high to key the rig (PTT to GND is standard) and 2) the
rig is easily over-deviated yielding an unusable signal.  The cure for
this that worked with my PK-232 interface are a follows: 1) install a
transistor inverter to deliver +5v to the PTT. I used a 2N2222 and two
2.2K resistors; the center pin of the mic connector is +5v.  2) install
a resistor in the FSK Out line from the interface. I used a 100K mini-pot
and then adjusted fo a usable output signal. These mods only took about
30 minutes and are both installed in the line from the interface.
   Hope that this helps anyone wanting to use the KDK FM-240 for VHF Packet
.  73 and good luck.  de KE5WJ "Skip" Slidell,LA.