These are amplifier units for photomultiplier tubes and current output type PMT modules. C7319: Switchable between 2 frequency bandwidths and 3 current/voltage conversion coefficients. Ideal for applications requiring low noise and high gain. C6438: Wide bandwidth from DC to 50 MHz and gain of 20 dB. (-01 type is 54 dB) C5594: High cut off frequency of 1.5 GHz. Faithfully amplifies high-speed output pulses. The input/output connector can be selected from the SMA or BNC types.