4-since the failure moves to lower amplitude as time passes, it is probably affected by heat. Why dont you spray some freeze spray (aim very locally) at different components and see if the error goes away. starting with that IGG5!
Did this. the only component that had effect using cold spray was the HMC346 it only shifted it down (lower db reading) but unlevel condition continued
tried the other board on the TG (one with OPAMPS and Analog Switch) , no effect there either
did you also try freezing the the capacitor and the schottky diode of the peak detector circuit?
based on the table you provided before, you should have got unlevel error even at -2dBm because the ALC_MON drops below -1V
and according to the schematics of A2A1 this will set the unlevel error. it is puzzling that you didn't get that.
something is happening between -3dBm and -2dBm. Can you try to measure the RF amplitude at these twi levels and see if the
RF actually drops? because the ALC_MON is reporting that it drops quite a bit instead of increasing by 1dB. So check the actual RF amplitude
(assuming IGG5 is ok, you can do it at the SMA port) if the actual RF amplitude does not drop then the problem is in the ALC_MON reporting
and the circuit between the schottky peak detector (and its ceramic cap) and the ALC_MON pin must be checked (most probably the opamp on the top right)
but if the amplitude does indeed drop, then I think the HMC346 is the main suspect.
by the way, is the frequency spot on?