[Elecraft] KAT100 signal question

[BobConvers at aol.com]

This is a new KAT100, just completed and under test.   I have never observed 
ANY relay action.
RYLOAD remains at 2.25v and bounces a bit each time I adjust, say,   ANT1 to 
ANT2.
RYCK appears   steady at about zero; and 5Megs to ground with no power.
U3-3 and U4-4 are always zero, also 5Megs to ground with no power.

RYDATA (at both U1-17 and U2-3) is interesting - its action varies according 
to setting of the K2 ATU menu.   When ATU is set to AUTO, adjustment of ANT1 
to ANT2 causes RYDATA to switch between zero and 5v.   When ATU is set to C3, 
for example, RYDATA remains constant at 5v with adjustment of ANT1 to ANT2 
(bounces a bit when switching).   However, when I powered down, and back up again, 
I could not always reproduce this exact behavior.

After playing around, I reached an ATU menu condition where I could see a 
five volt swing as I switched between ANT1 and ANT2.   I looked for a similar 
swing at U2-18 and U3-3.   There was no corresponding swing, always zero.   Am I 
correct that the finger of suspicion is beginning to point at U2?


>>>>>
None of these measurements really say anything. What is the level of 
RYDATA, RYLOAD and RYCK at both the MCU and U2, U3 and U4?

Have the relays ever worked, or is this a new unit? You might want to 
check the solder joints at pins 15, 16 and 17 of the MCU, as well as 
those at pin 3 of U2, and 12 and 13 of U2, U3 and U4. Lastly, cycle 
through the K2 menu's C and L settings to check for any relay action. 
It is quite possible that the KAT100 is simply not commanding the 
relays to change - the question in that case is why not?