Chiller swap

The TCSX chiller (S/N 617) was swapped with the spare (S/N 813) after I found a large puddle under the chiller this morning. When found, it was still running but the reservoir was almost empty. I turned it off, unhooked it, and opened it up to find the shaft seal leaking. Camilla was up here yesterday and didn't notice any water, so it's a bit surprising that this popped up quickly as it did. Either way, we have one seal kit on site so we will fix it in the next few days and have a usable spare again.

The spare chiller (S/N 813) also looks like it might have a shaft seal that is starting to go, evident by the black debris around the shaft. I couldn't get a good picture, but I'll keep an eye on it over the coming weeks.

RF hunt

Once that was all figured out, Camilla and I brought out the RF power meter and checked the output of the SG382. We verified what Daniel found back in alog65171 that the N-type output wasn't outputting the correct power, but the BNC out was okay. The correct power output settings according to the TCS Laser Projection System Recovery Procedure are 11dBm and 40.68 MHz. With these settings, and on the BNC output, we would get 9.8dBm at the RF distribution amplifier without the 2dBm attenuator in (added in 2015 I think - alog17314). Setting the SG382 to 13dBm and keeping the attenuator in gave us exactly the 10.0dBm spec'd. We hoped that this would be the single fix that would solve our TCS power issues, but it made little to no change in the output of either laser.

To get more power out of our current setup I'm hoping to acquire some ~75/25 beam splitters for BS1 [table drawing]. This should be good enough for our FLIR imaging and we can calibrate the PD to match. This is a cheaper and maybe faster solution until we either get new lasers or refurbish what we have.

SG382 Settings:

Modulation: OFF

Freq: 40.68MHz

Phase: 0.0

Ampl: 13.0dBm (with attenuator in at distribution amp)