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Size: 1992
Comment:
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Size: 1995
Comment:
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| Deletions are marked like this. | Additions are marked like this. |
| Line 9: | Line 9: |
| Alessandro, Martino, Dave, Angel | Alessandro, Martino, Dave |
| Line 13: | Line 13: |
| * End of May: NIKA2 warm-up | * '''End of May: NIKA2 warm-up''' |
| Line 15: | Line 15: |
| OK | OK, done. |
| Line 17: | Line 17: |
| * June 2nd: Alessandro, Martino & Dave arrive to the telescope. | * '''June 2nd''': Alessandro, Martino & Dave arrive to the telescope. |
| Line 19: | Line 19: |
| * June 3rd: Opened the cryostat from the back without moving it. A bit tight but feasible. Replaced the amplifier YL022 (probably faulty) with the official spare YL026 that was already at the telescope. After checking the connector we conclude it is pretty robust, well done and pity to cut the wire so we decide to bet on the fact that the problem was INSIDE the amplifier. Also our theory is based on the behaviour of the YL022 in past cooldowns. Not just OPEN/CLOSE, also doing strange things (high current) at intermediate temperature. In any case we have replaced, then verified that it was working (using Dave's portable VNA). | OK, done. * '''June 3rd''': Start working Opened the cryostat from the back without moving it. A bit tight but feasible. Replaced the amplifier YL022 (probably faulty) with the official spare YL026 that was already at the telescope. After checking the connector we conclude it is pretty robust, well done and pity to cut the wire so we decide to bet on the fact that the problem was INSIDE the amplifier. Also our theory is based on the behaviour of the YL022 in past cooldowns. Not just OPEN/CLOSE, also doing strange things (high current) at intermediate temperature. In any case we have replaced, then verified that it was working (using Dave's portable VNA). |
| Line 21: | Line 25: |
| Plan is to start cooling down tonight at 20h. Plan of the cooldown is check if the problem was really in the amplifier of the C box. | The cooldown started at 18h. Goal of this cooldown is to check if the problem was really in the amplifier of the C box. |
| Line 23: | Line 27: |
| [[attachment:IMG_6931.jpg|{{attachment:IMG_6931.jpg|VNA scan with -50dB attenuation on input|height=600}}|target="_blank"]] VNA Scan with -50dB attenuation on input |
Left: 4K BEFORE the change (YL022 ampli). Right: 4K AFTER the change. |
| Line 30: | Line 32: |
| Top: 4K BEFORE the change (YL022 ampli). Bottom: 4K AFTER the change. | VNA Scan with -50dB attenuation on input after replacement. |
| Line 32: | Line 34: |
| [[attachment:IMG_6931.jpg|{{attachment:IMG_6931.jpg|VNA scan with -50dB attenuation on input|height=600}}|target="_blank"]] | |
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* June 4th (daytime): Reserved as a backup. [[DailyReportsNika2Upgrade2025_2 |Daily Reports]] |
* '''June 4th (daytime)''': Reserved as a backup. |
Cryostat intervention (June 2-4, 2025)
According to the decisions taken during the April 11th meeting (see the minutes here), the next intervention aims to replace the array 2/box C LNA. It is provided to do that on June 3rd.
Participants
Alessandro, Martino, Dave
Overall schedule
* End of May: NIKA2 warm-up
OK, done.
* June 2nd: Alessandro, Martino & Dave arrive to the telescope.
OK, done.
* June 3rd: Start working
Opened the cryostat from the back without moving it. A bit tight but feasible. Replaced the amplifier YL022 (probably faulty) with the official spare YL026 that was already at the telescope. After checking the connector we conclude it is pretty robust, well done and pity to cut the wire so we decide to bet on the fact that the problem was INSIDE the amplifier. Also our theory is based on the behaviour of the YL022 in past cooldowns. Not just OPEN/CLOSE, also doing strange things (high current) at intermediate temperature. In any case we have replaced, then verified that it was working (using Dave's portable VNA). We then close the cryostat but have a leak on the OR, open/close again and the leak is gone after tightening the screws in the back. The cooldown started at 18h. Goal of this cooldown is to check if the problem was really in the amplifier of the C box.
Left: 4K BEFORE the change (YL022 ampli). Right: 4K AFTER the change.
VNA Scan with -50dB attenuation on input after replacement.
* June 4th (daytime): Reserved as a backup.