The Demod board with S. No. 022 (being used earlier as REFL11) has been modified. It now has SCLF-65 as its input LP filter on the PD input line and a PQW-2-90 power splitter. The unit functioning okay (I and Q signals are 90 deg apart.
The loss of Q output was traced to a possible loose solder joint and we now have both the I and Q signals after resoldering all components in the vicinity of U7 (Ref Schematic of D990511)
There is a strong oscillation around 350Hz present on I and Q signals of both REFL55_Demod and POY55_Demod. Don't know the source.
We have run out of power splitters to continue with the Demod board modification. We do not currently have an AS11_Demod board. All the others are in place and ready for the I<->Q phase angle measurement.
In summary we now have the following Demod boards in place:
[ REFL11, POY11, REFL55, AS55, POY55, POY22, POY110]_Demod