| 摘要 |
PURPOSE:To exchange units constituting a main line amplifier, that is, an equivalent unit, pseudo line unit, and amplifying unit without wave stop. CONSTITUTION:A by-pass amplifier 30 is connected between a status signal transmitting terminal 21 and an input monitor terminal 22. A transmission loss from the branch side of a second branching device 7 to a main path output side is large as an inverse coupling loss 40dB, and a branch high frequency signal amplified by the by-pass amplifier 30 is not substantially outputted to an amplifying unit 8. In a moment of taking out an equivalent unit 5 or a pseudo line unit 6, an impedance at the time of viewing the upstream side of the main path from the input terminal of the second branch device 7 becomes immediately infinite, and the transmission loss from the branching side of the second branch device 7 to the output side of the main path becomes a branching loss 20dB. Therefore, a down high frequency signal is supplied through the by-pass amplifying unit 30 to the amplifying unit 8 by an attenuating amount of almost 0 against the signal level of an input terminal 2.
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