With Aso-san and Terrence.

Summary: we began testing a possibe way of improving the situation of the LVDT in the F1 GAS filter. The problem with the LVDT is that the secondary coil has a stray connection to ground (18264). We still don't have conclusions and investigation will continue next week.

Today we tested an electronic circuit adapter that does the following:

• It routes the reference signal to the secondary coil rather than to the primary coil and uses the primary coil as readout. This seems to work in SRM IP LVDTs, in which there was an error in putting the pins in their nominal places in the connector, so we want to test this scheme for this LVDT.
• It converts the output, with the reference signal for the LVDT, from a double-ended output to a single-ended output. This enable us to cope with the stray connection to ground.

One of the symptoms of the problem is that the LVDT signal is noisier than when the stray connection to ground appeared. This means that we should aim to characterize the noise reduction in order to judge whether this strategy works or not. We didn't have much time to do measurements, but we did notice that the new electronics changes the overall amplitude of the signal, including the noise.

We will continue the investigation next week.