Teardown, Repair & Experiments with an Agilent 86118A 70GHz Dual Remote Sampling Head

In this episode Shahriar diagnoses a malfunctioning Agilent 86118A 70GHz Dual Remote Sampling Head. With 70GHz of analog bandwidth per channel, this module definitely deserves a repair.

Unfortunately most failed remote-head modules aren’t repairable if the damage is in the sensitive proprietary III/V front-end IC. However, in this situation the module intermittently fails calibration which is more promising. The teardown reveals the architecture of the module from the point of view of the analog and strobe paths. Measurements on the strobe path also show a potential failure on the power-amplifier/splitter network which feeds the two remote-heads. A pair of transistors are replaced on the strobe path which correct the problem. The unit passes calibration and is then used for various eye-diagram measurements to verify full functionality.

One comment

  1. James says:

    Hi Shahriar,
    Another nice save!
    Before dissecting one of these sampling heads, do you still have a sampler from TSP#83? I left a comment for that episode because I thought that I recognized a likely NLTL IC in your images of the insides of that sampler. I believe that HP/Agilent/Keysight have used NLTL’s to speed up strobe pulses on all samplers over 50GHz, and it is likely that the insides of your working 70GHz samplers are similar to that earlier broken one.
    Keep up the great videos.

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