[kTanaka, Hirose]

We checked f3 signal to go to EOM2b. We found that the f3 signal was coming to the input of the EOM with the same modulation index as f1. We noticed that the N-SNA conversion adapter was loose during the process. We would like to measure the modulation depth again in this condition.

## Detail

• The RFamp inputs for each of f1, f2, and f3 were measured with Moku-lab's Spearna. 
  The RFamp input for each of f1, f2, and f3 was about 6 dBm. This was after lowering the attennator -2dBm from the multiplier's output of 13dBm, so it is lower than that.
  We then measured the RFamp output of f3 and it was about 6 dBm.
  Fig1: Noise level before measurement.
  Fig2: The blue and red results are for f1 and f3. There are the same 6 dBm peaks at f1 (about 16.8 MHz) and f3 (56.8 MHz), respectively.
  Fig3: The red result is for f2. The bule result is the output of the f3 RFamp.
   
• The input for f1 and f3 of EOM2b was about 13 dBm. It indicates that the f3 signal is coming to the input of the EOM with the same modulation index as f1. (However, the RFamp output results are just different, so it is strange.)
  During the previous modulation depth measurement, the f3 signal was not visible. During the course of this measurement, we noticed that the N-SNA conversion adapter (attached between the output of the f3 RFamp and the SMA cable) was loosened. Since we could not take measurements to compare before and after tightening the adapter, we cannot determine why we could not see the f3 modulation depth. Now we found that the f3 signal is coming to the input of the EOM2b through this work, so we would like to measure the modulation depth again.
  Fig4,Fig5 : The photo around EOM2a and EOM2b. The current situation is that light does not pass through EOM2a, but light does pass through EOM2b.
  Fig6: Noise level before measurement.
  Fig7: The red and blue results are for f1 and f3. 

## Process

This time we checked the RFamp input and output, taking care not to unplug the cable while the signal was going from Seed's function generator. We summarized for future use.

1. Turn off "RF output" on the seed function generator.
   --->> The seed function generator was in remote mode, but we switched to local mode using a dedicated web page. we could not find out how to switch back to remote mode, so it is still in local mode.
2. Turn off the DC power to the multiplier.
3. Turn off DC power to the RFamps(f1, f2, 2f2, f3 in the IOO rack, f1, f2 in the ALS1 rack, f1, f2 in the LSC rack, f1 rack in the OMC rack) connected from the multiplier.
   -->> If we want to see the output of a circuit, we should turn off the power to that circuit, but RFamp can be corrupted by glitches, so we have included this step.
4. Connect the spare to the signal to be acquired using an SMA cable.
5. Turn on DC power to the RFamps.
6. Turn on the DC power to the multiplier.
7. Turn on "RF output" on the seed function generator.