As a simple check of the gains on all the quadrants I hooked up the AM (Jenne) laser to put FM modulated light on to the WFS heads and observed the FM modulation frequency , 105 Hz, show up on a power spectrum of the RF outputs. The plots below show the peak at 105Hz in all the quadrants.
However I should have put in AM modulation rather FM modulation. I will do that using the digital system today. The first version above was done wth a Marconi driving the AM laser modulation.