[Dick / Kiwamu]
We found an RF cable whose signal level depends on the angle of one of the cable end. This is not good. I consulted with Filiberto on this issue and we decided to leave it to the electricians who are coming in the next week from Caltech. Or if the cable turns out to be necessary soon, we can just swap or fix it by ourselves.
--- the Cable
place: remote rack C4
connection between : U42-1 and U9-1
description:71 MHz for a VCO
length: ~ 2 m
type: N male / N male
--- Symptoms
* The RF power dropped from 11 dBm to -8 dBm suddenly while doing nothing
* Applying tension at the cable end (the U9-1 side) introduces variation in the RF power by ~15 db or so.
--- Assessment
At the beginning we thought that the power variation was due to the connector which is a part of the U9 circuit box (i.e. the channel 1 output of an RF distribution amplifier D100024/S1000595). We pulled out the circuit box and brought it to the EE shop to do a further investigation. We didn't find anything wrong. So we put the box back to the rack and it seems working fine.
Eventually we located the issue and confirmed that it was in the RF cable and not in the box. Currently everything is back to place.
I have just removed the cable and cut it so that noboday can accidentally use it.