Sheila, Rana, Kiwamu, Alexa, Daniel

We had not been able to lock the PRMI all of today. During the day's usual ISI shaking we noticed that the AS beam had gone nearly of the camera and so spent awhile chasing trends, etc.

After not finding the cause of that, we noticed that the AS45 and REFL45 signals had dropped off to nothing around 3AM local time. As far as we can tell, no one was on site at the time.

Afer some hunting, we found a particularly horrible electronics setup for the 45 MHz modulation amplifier in the H1 CDS electronics room on the same rack as the 9 MHz Marconi generator:

There was an unsecured ZHL-1A amplifier on top of the rack, powered by a DC bench supply (of the lowest quality available), and connected by damaged Banana cables. The banana power cables are intermittent and turn off the amplifier power once in awhile. We could see the power supply current vary to any value between 0 and 400 mA as we brushed the cables - I wouldn't trust this amplifier any more.

Several people disavowed any knowledge of this setup (even after we found https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=11986). It contained a few low quality L-Com cables and several cheap BNC barrels. We must never use BNC connections and these kinds of unreliable adapters in our low noise RF setups. Only N and SMA connections are allowed.

We have relocked the PRMI after removing this setup. The modulation voltage for 45 MHz is now 4x lower. It would be best to make a higher quality RF amplifier setup underneath the PSL table as was done at LLO. We'll be using this weaker modulation for another few days, but we want the higher modulation depth by mid next week, when we get back to the 3f locking.