daniel.sigg@LIGO.ORG - posted 15:05, Tuesday 22 April 2025 - last comment - 14:05, Wednesday 23 April 2025(84065)
Issue with ISC_RF25-B/3
Marc Daniel
One of the coax cables shows a discontinuity at the feedthrough, ISC_RF25-B/3. This is the coax for ASC-REFL_B 9MHz chn 4 (Q4 RF Low). This is feedthrough D1-1D1. We can see the signal going though the pig-tail but terminating at the feedthrough. This could be an issue of the in-air pig-tail or the in-vac cable at the feedthrough side.
Typical In-vacuum RFPD ASC Wiring Chain for aLIGO: https://dcc.ligo.org/LIGO-D1300467
O5 ISC/SQZ Wiring Diagram: https://dcc.ligo.org/LIGO-D1900511
TDR Plot of the cables analyzed.
Found faulty pin on one of the Accu-Glass 5-way coaxial pigtails. Pin 3 seems to have been improperly crimped/seated/damaged. See attached picture. The Pigtail cable was replaced. Initial testing shows all pins are now correct lengths. The cable with issue was ISC-RF25-B/3.