11301
The Tektronix 11301 is a programmable 400 MHz analog oscilloscope that takes up to three
11000-series plug-ins or (vertical) 7000-series plug-ins.
Note, however, that the 7000 series plugins have mechanical interlock preventing them from being installed into an 11K mainframe.
The sister model 11302 is basically identical but has a micro-channel plate CRT and 500 MHz bandwidth.
The 11301 has an infrared beam touch screen. There are 10 columns and 14 rows of beams.
The 11301 contains a 77 nanosecond delay line.
Key Specifications
| Bandwidth | 400 MHz |
|---|---|
| Sweep | 5 ns/Div to 500 ms/Div, 1-2-5, ×10 magnifier (same specs for delayed time base) |
| Triggering | 0.35 Div (int) or 20 mV (ext) to 50 MHz, increasing to 1 Div/150 mV at max. bandwidth |
| Trigger modes | DC, AC (>50 Hz), HF Reject (< 30 kHz), LF reject (>80 kHz), TV (line or field) |
| X-Y operation | X from center plugin, bandwidth 3 MHz X-Y phase difference <1° to 1 MHz, <3° to 2 MHz |
Internals Common to the 11301 and 11302
In this section, "11300" refers to the 11301 and 11302.
The 11300 is a digitally controlled analog oscilloscope. Like a typical analog scope, the 11300 has vertical amplifiers, a trigger circuit, a timebase/sweep, a horizontal amplifier, and a CRT. Unlike traditional analog scopes, an 11300 system contains contains a significant amount of digital circuitry, including multiple microprocessors, one in the mainframe and at least one in each plug-in. The digital circuitry provides several externally-observable features:
- self-test and diagnosis
- self-calibration
- remote control via RS-232 or GPIB
- on-screen menu-based touch screen user interface
Digital circuitry also implements some features that were traditionally implemented with analog circuitry, e.g., the trigger holdoff is implemented with a counter instead of with a multivibrator.
There are many DAC-generated analog control voltages in the 11300.
The left and center plug-in can be used as the vertical axis and/or the trigger signal. The right plug-in can used as the horizontal axis and/or the trigger signal.
The RS-232 interface of the 11301 is implemented using an 8251A UART chip, interfaced using an MC1488 line drive and an MC1489 line receiver.
The mainframe communicates with the plug-ins via the Serial Data Interface (SDI). SDI was designed by Lester Larson. This communication bus comprises three signals:
- SDI clock
- SDI mainframe to plug-in
- SDI plug-in to mainframe
On the mainframe side, this communication is controlled by the U1760 SDI IC (Tektronix part number 156-2622-00) on the A11 Main Processor board, which is at the top rear of the scope. The 11301 SDI is a synchronous serial interface. The clock signal, which is generated by the mainframe, is 5V TTL, 4 MHz, constantly running.
The 11300 performs a variety of self-checks and self-calibration. Some of the self-checks are digital in nature, e.g., testing RAM by writing a pattern, reading it back, and comparing what was read with what was written. Other tests are analog in nature. For the analog tests, there is an analog bus, ABUS, that allows various voltages throughout the scope to be measured by the test routine. The ABUS is a fan-in tree formed by 74HC4051 analog multiplexers. One level of multiplexing happens at the module level. The ABUS signals from each of the modules are brought to the main ABUS multiplexer (lower left corner of schematic drawing 12, Partial A11 Main Processor Board). The output of the main ABUS multiplexer is fed to an LF398 sample and hold IC, the output of which is fed to an AD574 12-bit successive approximation analog to digital converter.
The 11300 has a GPIB interface implemented using a TMS9914A GPIB controller IC.
The 11300 uses a TMS4500A DRAM controller to manage a bank of 41464 DRAM chips.
The main CPU in the 11300 mainframe is an Intel 80186. Program memory for the 80186, i.e., firmware, is stored on eight 27512 EPROMs. Four of the EPROMs contain the lower bytes and the other four EPROMs contain the upper bytes. This is shown on schematic figure 9, Kernel.
The 11300 has a real-time clock powered by a 3V lithium battery. The real-time clock is a 6242 IC.
