11300
The Tektronix 11300 is a series of digitally controlled analog scopes. The series consists of four models:
The four 11300 models have most of their circuitry in common. They differ in only two respects:
- 11302 and 11302A have a micro-channel plate CRT whereas 11301 and 11301A have a non-MCP CRT
- 11301A and 11302A have 750 MHz counters, whereas 11301 and 11302 have 500 MHz counters
The MCP CRT has a smaller graticule than the non-MCP CRT.
The 11300 vertical signal path starts with a plug-in amplifier. The signal from the plug-in goes to the channel switch. The output of the channel switch goes to the vertical amplifier. The vertical amplifier drives the deflection plates of the CRT.
The 11300 horizontal signal path starts with the plug-in amplifier. The plug-in provides a trigger signal to the mainframe. The trigger signals from the plug-ins are fed to the A and B trigger circuits. The A and B triggers control the start signal of the A and B sweeps, respectively. The A and B sweep outputs (ramps) are fed to the horizontal amplifier, which contains an input multiplexer. The output of the horizontal amplifier drives the deflection plates of the CRT.
The A and B triggers also send trigger pulses to the counter/timer circuit. The counter/timer measures the time between trigger events.
11300-series scopes contain a significant amount of digital circuitry. The digital circuitry is not in the signal path. The mainframe has a 80186 microprocessor. Each 11000-series plug-in contains an 8051-family microcontroller. In addition to the microprocessors, the mainframes and plug-ins contain custom Tek digital ICs.
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. These are produced by the Analog Control Voltage System.
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), which is part of the 11000-series plug-in interface.
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 3 V lithium battery. The real-time clock is a 6242 IC.
The A sweep and B sweep are each generated by 155-0240-00 ICs.
The vertical amplifier in 11300 mainframes is U520, an H2053 hybrid with part number 165-2053-00.
Full calibration of an 11301 requires the use of the TEKCATS software.
Calibration constants are stored in an Intel D2817A EEPROM.
The 11300 scopes have a counter/timer IC, Tektronix part number 230-0022-50. The die is M229.