The Tektronix DM 502A is a 3½ digit autoranging digital multimeter module for the TM500 plug-in system. It delivers true RMS AC measurements across voltage, current, resistance, dB, and temperature functions. The autoranging architecture simplifies operation on DC/AC voltage, dBm, dBV, and resistance; current and temperature ranges require manual selection. Built-in offset circuitry enables direct dB readings without external calculations.
Technical Specifications
Measurement Functions
• DC Voltage
• AC Voltage (True RMS)
• DC Current
• AC Current (True RMS)
• Resistance (200 Ω to 20 MΩ)
• dBm and dBV
• Temperature via PT-100 probe (P6601)
Display & Control
Seven-segment LED readout with automatic polarity indication. Autoranging applies to DC voltage, AC voltage, dBm, dBV, and resistance; current and temperature ranges are manually selected.
DC Voltage
Input impedance 10 MΩ ±0.5% paralleled by <60 pF. Front panel: maximum 1 kV peak. Rear interface: maximum 200 V peak.
AC Voltage (True RMS)
Input impedance 10 MΩ ±0.5% paralleled by <60 pF. Front panel: 500 Vrms maximum, not exceeding 1 kV peak. Rear interface: 500 Vrms maximum, not exceeding 1 kV peak. Usable frequency range 20 Hz to 20 kHz with ±1.1 dB accuracy for +50 dB to -50 dB ranges; extends to 100 kHz on selected ranges.
Current (DC & AC, True RMS)
Maximum input current 2 A on any range. Front panel input only. Maximum open circuit input voltage (mA to LOW terminals): 250 V peak.
Resistance
Accuracy ±(0.8% of reading + 1.4% of full scale) across 200 Ω to 20 MΩ ranges. 2 kΩ range supports diode testing with 1 mA current source, displaying forward voltage drop to 10 V.
Temperature
Manually selected ranges for PT-100 probe measurement from -55°C to +200°C. Option 2 units omit temperature function.
dB Measurement
Direct readings with ±1.1 dB accuracy from +50 dB to -50 dB, 20 Hz to 20 kHz.
– Key Features
• True RMS converter for non-sinusoidal waveform accuracy
• Autoranging eliminates manual range switching on voltage, resistance, and dB measurements
• Dedicated offset circuits for direct dB readings without external reference
• Automatic polarity detection
• Compact plug-in module design
– Typical Applications
Audio and RF measurement, component characterization, temperature monitoring, and signal verification within TM500 mainframe systems.
– Compatibility & Integration
Designed as a plug-in module for Tektronix TM500 system. Supersedes DM502 with added autoranging and true RMS capability.
