Marc, Matteo

We brought a DC voltage supply from the elec shop to the FC clean room.

First, we used it with the 500 MHz clock after the first voltage regulator. We could see the on the spectrum analyzer the 500 MHz peak from all the output channels.

Then, we tried to use it with DDS boards and found that all the expected voltage were provided.

However, when connecting 1 DDS board to the nim rack, we could not get any voltage (about 0.2 V and fluctuating).

After some checks, we found out that the high quality ground of the nim rack is not working while with the ground we can get the +/-24V, +/-12V and +/-6V.

We found similar issue for the spare nim rack that was used to control TAMA BS and PR.

However, the high quality ground of the nim rack used for the QPD is working properly.

We connected the 3 DDS boards and the 500 MHz clock to this rack and got the 500 MHz signal as well as all expected voltages.

We also checked that all the boards installed on this rack do not use the high quality ground, so we will swap this nim rack with the one previously used for the DDS boards and the 500 MHz clock.