I have made a SMA cable of length 1.952m after optimizing phase delay of LO. This is giving the maximum PDH error signal.

For future reference, I'm saving present setup details:

• Off-resonance South Reflection RFPD SN010: 3.34 V
• Resonance dip in South Reflection RFPD SN010: 2.98 V
• Cavity Transmission Peak: 3.6 V
• OUT1 peak-to-peak signal: 230 +- 5 mV

From the ratio of off-resonance value and error signal pk-pk at OUT1, we can check in future if everything is same as right now. From ratio of off-resonance value and dip value, we can check cavity  mode matching in future.