7912

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500/750 MHz Digitizer Tektronix 7912AD with 7A26 and 7B90P Produced from 1974 to 1989 Manuals R7912 ... 7912AD/HB 7912AD Operator's Manual (partial, 57 pages from introduction) 7912 and related digitizer documents 7912AD Reading Gun Supply 7912AD Writing Gun Supply (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

The Tektronix 7912 was a series of high-speed digitizers that take one 7000-series vertical plug-in and one 7000-series horizontal plug-in.

All 7912 models use the same internal CRT-based, digitizing scan converter tube (T7912) that is not visible from the outside. The signal from the vertical plug-in deflects a writing beam through distributed deflection plates. The electrons hit a small flat rectangular solid state target, conceptually similar to that in a digital camera. The resolution of the target is 512×512, giving 512 points in the time domain and 9-bit linear quantization of the input voltage.

With a 7B92 sweeping the whole X-axis in 5 ns, and the 7912AD capturing 512 samples in that sweep, the 7912 performs the function of a 100 GSample/s ADC.

R7912

The R7912, introduced in 1974, had a proprietary digital interface. A card for interfacing to a DEC PDP-11 was available. The Tektronix WP2000 (067-0679-00) Digital Display Controller is an external module that interfaces with the 7912. Tek also offered configurations with multiple R7912s on a common controller within the WP2000 series.

The R7912 used the 7000 series readout system writing readout characters onto the storage target, which would become part of the output signal in the NON STORE mode.

7912AD and 7912HB

From the 7912AD (1978) on, the instrument had a standard GPIB interface. The 7912AD has 500 MHz bandwidth. It was succeeded by the 750 MHz 7912HB in 1987.

For the 7912AD and 7912HB, special GPIB-controllable plug-in modules with a 'P' suffix, meaning Programmable, were available, e.g. 7A16P, 7A29P and 7B90P.

Internals

The signal goes from the vertical plug-in to the vertical amplifier to the digitizing tube where it deflects a beam of electrons.

The trace is read from the target by electronics in the 7912AD, digitized, and stored in memory. The reading of the target is asynchronous to the sweep and therefore the tube can be considered a form of scan converter.

Three output methods are provided: NTSC-out, X-Y low-speed analog, and a GPIB interface.

Bypassing the vertical amplifier, the 7912 can provide a bandwidth of 1 GHz with a sensitivity of 4 V/Div.

With aftermarket modifications to the electronics, 7912AD bandwidths have been extended up to 3 GHz in special cases.