Hmmm. Very non-standard demod. From the photo, looks like someone did some surgery with the attenuators (AT1, AT2, AT3) in the LO path. (might be me from a long time ago).
-8 dBm input to a circuit is a not a low noise situation. It would be best to remove the amplifiers in the I&Q paths and just have a single amplifier in the main path. Ideally we want the LO to never go below -3 dBm and certainly not below 0 dBm while outside of the board.
I doubt that all of the LSC demods were modified in this way - this one ought to get some sharpie or stickers to show its difference. |