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I bought 2 'faulty' 3762A units for spares or repair on eBay for £10.  Their original cost was $9,125 each in 1980.  These versions were made for British Telecom to test 68 & 140Mbit/s transmission systems.  The BT reference is "Tester No 273A/HPU/1". So far I have not been able to download a Service Manual from HP or BT, but still looking!






Front view




Rear view





Top view with cover removed





Bottom view with cover removed





July/August 2007


These units are very well constructed and the only damage was one bent front panel and various broken switches.  Easily swapped over to make one good unit.  No actual faults were found.  The original intention was to re-use the switches for a different project as this was much cheaper than buying just the switches!


Once I had figured out what the equipment did, I decided to keep it as a useful signal/pulse generator.  The external clock input means that it can generate a wide range of pulse frequencies and configurations.  I haven't yet decided what to do with the second unit.  Lots of useful spares in it, but finding the Manual would be good start.


The 3762A Data Generator produces PRBS and WORD sequences in the frequency range 1 kHz to 150 MHz.  Internal crystal oscillators provide clock and data outputs at two frequencies f1 and f2, where f1 and f2 depend on instrument option.  An external clock signal is required to provide clock and data outputs over the complete frequency range.  Burst mode control of the Data Generator is possible via a burst gate input.


Clock and data inputs, generated from internal frequencies, can be offset by up to +- 60ppm from f1 or f2.  Data output format is Coded Mark Inversion (CMI) at frequencies 139.264Mb/s and 141.040 Mb/s or Binary (RZ or NRZ) over the complete frequency range.  Option H76 provides frequencies of 139.264MHz (f1) and 68.736MHz (f2) for BT 140Mbit/s and 68Mbit/s.




October 2010


Have now acquired the companion HP 3763A Error Detector.  Testing of both units is held up by needing the Operating & Service Manuals.

January 2011
Download Operating Manual for 3762A and 3763A.
August 2015
Fails Operator's Checks so more work required.
Please contact me if you have a copy of the Service Manual.