This units works well.  the Series Number is US36309168.  The calibration was done on Jan 03, and was due on Jan 04.     

The Agilent 83446A lightwave clock/data receiver is designed to extract clock and data information from digitally modulated lightwave signals at the SONET/SDH data rate of 2.48832 Gb/sec (OC-48/STM-16). It incorporates a high-gain avalanche photodiode (APD), gain-controlled amplifier, and clock/data recovery hybrid to deliver clean, error-free outputs from optical signals with powers as low as -27 dBm at either 1310 or 1550 nm wavelength.

     The Agilent 83446A has been designed especially for use with high-speed bit-error-ratio testers (BERTs) such as the Agilent 86130A or 71612C. By connecting the clock and data outputs to the corresponding inputs on the BERT'S error detector, bit-error-ratio analysis can be performed directly on optical signals, making it easy to do system acceptance and BER floor analysis. The Agilent 83446A also has an auxiliary port which allows monitoring of the output of the APD prior to regeneration.

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