J. Kissel, F. Clara
ECR E2400330

Fil modified the UK SatAmp (D0900900 / D0901284) per ECR E2400330, which means "rev'ing" up the D0901284 circuit board inside from -v4 to -v5 (thanks Michael Laxen for the updated drawing!). 

This mod changes the whitening stage frequency response by adjusting the (R180, R181, R182) values from (750,20e3,20e3) to (1.5e3,80.6e3,80.6e3) Ohm, causing the zero:pole pair to move from z:p = (0.384 : 10.6) Hz to z:p = (0.0969 : 5.31) Hz.

I then measured the frequency response with the nearly*** identical procedure as described in LHO:85349. 

The measured results agree with the expected model of z:p = (0.0969 : 5.31) Hz (and a ~7 kHz high-frequency pole) to within +/-1.5% and +/-1.0 [deg], as was the case for the measured results when this same board was at -v4.

I think we're good to go for rev'ing up many of these satamps, and can have excellent confidence in compensating every channel of every satamp with a z:p = (5.31 : 0.0969) Hz digital filter.

***The only difference is that I needed to drop the source voltage from 0.3 V_SRC to 0.2 V_SRC in order to prevent the differential output stage opamps from saturating. Note -- the saturated response was only ~7% different from expectation and only above the frequency-dependent output of the whitening stage exceeded the ~14V that the differential output opamps can push; I got clued in to this subtlety and have a quantitative answer because the ratio between saturated model and measurement sharply kinked up at 6.39 Hz, and rose up to 7% -- consistent across all four channels -- in a non-linear way that couldn't be explained by adding more zeros and poles. #ThreeHoursWasted