First let me thank you all for your suggestions, all were very much appreciated.
These units have been removed from the radio:
I have also removed the KAT board and made a direct connection.
There is low power output in the KXV3 test mode.
The KLPA3A is Rev B. Looking at the schematic, taken from the web, which is also for Rev B there are differences between what the schematic shows and what is in the radio. There are 2 relays KL2 and KL3 on the schematic that are not on the board in the radio.
With tune on there is 1 volt p to p input and 2.4 volt p to p output on the KLPA3A.There are no change in these readings on power control adjustment. I have not yet understood how power control adjustment is implemented.
4 dBm would seem adequate drive for the KLPA3A.
What is the part number of U4 is not given on the schematic?
I have not seen anything obviously wrong on the KLPA3A but the voltage gains throughout seem low.
73 Brian KF6C.