2nd Change of NIKA2 Box-C LNA (Array 2)
Historical context
Bad surprise during NIKA2+ re-commissioning in April 2025 we practically lost 1/4th of Array 2, Box-C line cold Low Noise Amplifier (LNA) was partially lost. See Run 72 wiki page and related sub-pages, in particular Discussion on online results and Further decisions where it was decided to change this Box-C LNA in June 2025. See also weekly meetings minutes pages from March 26, 2025 and following weeks.
In June 2026 Box-C LNA was changed. See Run 32 wiki page and related sub-pages. This solved the problem... For a limited period. On January 6, 2026, Alessandro and others noticed an excess noise on BOX-C line again. See descriptions in 6-13 January 2026 - w25 Pool #2 Daily Reports, and January 7th, 2026 NIKA2 weekly meeting. It was then decided to change the amplifier one more time, but this time with a different kind than the ones used till now (LNAs used till now = YEBES 3-stages; new kind of amplifier = ASU 1-stage). See January 14th, 2026 NIKA2 weekly meeting, and following week..
Report on Box-C LNA change, YEBES 3-stages LNA replaced with a ASU 1-stage amplifier (1st one of this kind in NIKA2)
See January 28th, 2026 NIKA2 weekly meeting and February 11th, 2026 NIKA2 weekly meeting for description of the amplifier change by Dave, Martino and Sergio. Somme cabling and adaptation pieces had to be made to adapt the mounting of the ASU LNA box the NIKA2 plug that was originally designed for the YEBES LNA box size. The intervention went fine.
Alessandro confirms good noise levels when monitoring the line after cool down.
Outcome on the 2nd Box-C LNA change
The 2nd Change of Box-C LNA is a success. See result on data from observations on sky described in the 10-17 February 2026 - w25 Pool #5 Daily Reports