The TTFSS beat-note is now measured as -15dBm RF  and -1.3V DC ( =sqrt(360uW*5k) ) with an optical power of 360 uW (180 uW from each arm) on the diode. Above this power the max DC does not occur at the same spatial position on the diode as the max RF (and only an extra .5 dBm or so in rf power is achieved). Note before correcting the mode matching (see alog44462) and now identifying detector saturation at much less than 1mW we were operational with a beat-note level of -23 dBm. Also with reference to alog44462 there is a 50/50 beam-splitter in place of MR17 to reduce the power on the diode. There is also an attenuator (60% transmission) and beam dump to optimize the power as the ideal combination of beam-splitters were not available. Note a range of spot sizes were tried on the diode for the above optimization.