We changed PMT north and PMT south and tested them at 1500 V.

Both new PMTs are broadband.

PMT north and middle see between 2 and 7 kHz signal rate with a threshold close to the background noise.
PMT south still has the plastic cap on and is intended to be used as a reference for electro-magnetic disruptions. No signal was seen at 1500 V.
We fixed the signal cable of PMT south to the NIM-crate to get rid of background noise picked up by the cable.