[Jeff B, Andres R, Rich A, Jeff L, Koji A]
We successfully resolved the grouding issue of the OMC preamps, thanks to the help provided from Peter K, Rick S, and Betsy B
for the necessary isulating materials. Here is the note for ourselves and someone who may work on this insulation for L1 and 3IFO.
The grounding of the ISC cables were caused by the mounting of the preamps (attached figrue, left). The PEEK washers
were used to isolate the bracket from the structure. In order to fit the wahsers, we had to trim them (only for the outer one) with crimpers.
In order to isolate the 1/4-20 screws from the hole walls, we used Kapton tubes. Since the diameter of the tube was too big
for the hole, we had to open the tube and trim it to reduce the number of turns. In addition, the metal washers should have
been removed as they sneakily caused the grounding with the preamp.
Additional note (Dec 8)
The preamps are touching the cable for the PZT signals. Therefore the installation of the isolation kit should be done
without removing the adapter plate in order to avoid misalignment of the glass breadboard.
This can be done by installing the isolation kit one side at a time:
1. Loosen the two 1/4-20 caps
2. Remove one of the screws while the adapter plate was kept at the installed position.
3. Insert an unmodified PEEK washer between the SUS structure and the adapter plate.
4. Put a trimmed PEEK washer on a screw. Roll a kapton tube around the screw.
5. Insert the screw combo into the screw hole.
6. Turn the inserted screw (not fully)
7. Repeat 2 to 6 for the other screw
8. Tighten the two screw.
9. Check the isolation between the preamp housings and the SUS structure.