Nishio, M. Futagawa, N. Kawashima, S. Nakajima, H. Nishikawa, K. Takabayashi, T. Tanaka, S. Torii, C. JACoW Publishing Geneva, Switzerland 2226-0358 978-3-95450-254-7 10.18429/JACoW-ICALEPCS1991-S10TS08 English 371-374 network controls linac detector gun Contribution to a conference proceedings 1992 1992-12 https://doi.org/10.18429/JACoW-ICALEPCS1991-S10TS08 https://jacow.org/icalepcs1991/papers/s10ts08.pdf A new phase-lock network using fiber-optic system was developed as a local signal distribution system for 84 antennas of the Nobeyama Radioheliograph. This network is an open loop system and consists of a master oscillator with an E/O converter, an 1-to-84 optical divider, phase stable optical fiber cables and phase stable phase-locked oscillators with O/E converters. Phase stability of the network and phase noise generated at the O/E converter are discussed. This phase-lock network insures the required phase stability of 3°/6 hours. The phase noise increases the coherent loss of 0.1 \% at the correlator output, which is very low. This is the first large application of fiber optic devices to an open loop phase-lock network. Our system is very simple and phase-stable. Therefore, it is suitable to the connected array with large number of antennas.