Schlumberger 4002: Components (Part 0)

The first thing I wanted to do[1] before starting this project was to get a general idea of the system layout, hence the “part 0” thing above. Also, this will serve as the master post, linking to the other pages when the time comes.

Extracting a simple connection diagram always helps to simplify things later on when tracing and verifying signals, and also when a sudden space-time-vortex comes along and throws all those neatly organised cables into a messy heap. Might happen to be a cat, too. So let us first cycle through the different modules and their approximate functionalities. Click the thumbnails to get a better view and more detailed explanations in the picture subtext. Also, be advised that my interpretation of things is not necessarily consistent with the original service documents.

Oven-controlled crystal oscillator (OCXO)

OCXO top compartment. Oscillator on the bottom right, distribution on the top right. 10.7 MHz mixer (10.625 MHz + 65-85 kHz) and filter in top center. Quad VCO and PLL for widerange signal in bottom center and left.

Fig. 1a: OCXO top.

Contained in the bottom right module block, consists of a styrofoam-encapsulated 10.000 MHz temperature-controlled oscillator and some clock distribution buffering. It delivers the main TTL clock that is also available on the backside ports as an instrument reference. The picture shows the whole top side of the module block, but the actual OCXO and distributor PCB are on the right. The rest of the circuits belongs to the next module, the RG.

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