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PS Transverse Feedback Pick-up Amplifier |
The range of intensity over which the system must work is much too large for a single range. Two stages of capacitive dividers can be inserted into the signal path. A 20dB section and a 40dB section allow for four different attenuation settings. Each attenuator is switched by the combined action of a reed relay (Pickering 103G-1-A-5/2D) and a pair of PIN diodes (BAR88-02V). The reed relay bypasses the series element, and the diodes switch the shunt element. The parasitic inductance of a relay, even a miniature one, in the shunt leg would cause it to resonate with the shunt capacitor within the passband, which is unacceptable.
