w140.com

DM501 - TekWiki

  • ️Mon Oct 07 1968
Tektronix DM501
4½ digit multimeter
Tektronix DM501

Produced from 1972 to 1980

Manuals

(All manuals in PDF format unless noted otherwise)

The Tektronix DM501 is a 4½ digit multimeter plug-in for the TM500 system.

(See DM501A for the significantly different successor model.)

It also has a temperature input, requiring the P6058 temperature probe with a 4-pin LEMO S-series connector. The manual states that certain NPN transistors such as a 2N2484 may be used as temperature sensors in place of the probe with little or no selection of the transistor.

The DM501 MOD718D variant replaced the temperature range with a 200 mV input range providing 10 μV resolution (see Physical Measurements Handbook).

Key Specifications

DC Voltage 2 VDC to 200 VDC in decade ranges (0.1% + 0.01% FS), 1000 VDC (0.1% + 0.02% FS); Input resistance 10 MΩ, CMRR >100 dB at DC, 80 dB at 60 Hz (1 kΩ unbal.), NMRR ≥30 dB at 60 Hz + 20 dB/decade
AC Voltage 2 VDC to 200 VAC in decade ranges, and 500 VAC (0.7% + 0.01% FS for sine inputs only); Input impedance 10 MΩ // ≤70 pF, CMRR unspecified
DC Current 2 mA to 2 A in decade ranges, 0.2% + 0.05% FS
AC Current 2 mA to 2 A in decade ranges, 0.6% + 0.05% FS (for 40 Hz to 1 kHz sine)
Ohms 2 kΩ to 20 MΩ in decade ranges, current 1 mA to 0.1 μA respectively; 0.3% (20 MΩ: 0.5%) + 0.01% FS
Temperature –55°C to +125°C (±1.5°C), +125°C to 150°C (±2.5°C)

Options

  • Option 1: Ordering without P6058 Temp Probe
  • Option 2: Without Temp Capability and Probe (visible by no Temp Out at the Front)

Links

Documents Referencing DM501

Document Class Title Year Links
Tekscope 1974 V6 N3.pdf Article The 31/53 Calculator-based Measurement Instrumentation Package John Mulvey 1974 31 • 153 • DM501 • DC503
070-2088-00.pdf Book TM500 Series Rear Interface Data Book 1975 AF501 • AM501 • AM502 • DC501 • DC502 • DC503 • DC504 • DC505 • DC505A • DM501 • DM502 • FG501 • FG502 • FG503 • MR501 • PG501 • PG502 • PG505 • PG506 • PG508 • PS501 • PS502 • PS503 • PS503A • PS505 • RG501 • SC501 • SC502 • SG502 • SG503 • TG501
070-2088-01.pdf Book TM500 Series Rear Interface Data Book 1976 AF501 • AM501 • AM502 • AM511 • DC501 • DC502 • DC503 • DC504 • DC505 • DC505A • DD501 • DM501 • DM502 • FG501 • FG502 • FG503 • FG504 • LA501 • MR501 • PG501 • PG502 • PG505 • PG506 • PG508 • PS501 • PS502 • PS503 • PS503A • PS505 • RG501 • SC501 • SC502 • SG502 • SG503 • SG504 • SW503 • TG501 • TR501 • TR502
070-2088-04.pdf Book TM500 Series Rear Interface Data Book 1985 AA501 • AF501 • AM501 • AM502 • AM503 • AM511 • DC501 • DC502 • DC503 • DC503A • DC504 • DC505 • DC505A • DC508 • DC508A • DC509 • DC510 • DC5009 • DC5010 • DD501 • DL502 • DM501 • DM501A • DM502 • DM502A • DM505 • DM5010 • FG501 • FG501A • FG502 • FG503 • FG504 • FG507 • FG5010 • LA501 • LA501W • WR501 • MR501 • PG501 • PG502 • PG505 • PG506 • PG507 • PG508 • PS501 • PS502 • PS503 • PS503A • PS505 • PS5010 • RG501 • SC501 • SC502 • SC503 • SC504 • SG502 • SG503 • SG504 • SG505 • SW503 • TG501 • TR501 • TR502 • MI5010 • MX5010 • SI5010

Patents that may apply to DM501

Page Title Inventors Filing date Grant date Links
Patent US 3562464A Cam actuated switch having movable and fixed contacts on circuit board Howard Vollum • Willem H Verhoef • Tony Sprando 1968-10-07 1971-02-09 Cam switches • 2101 • 2701 • 2703 • 432 • 434 • 465 • 475 • 5A15N • 5A18N • 5A20N • 5A21N • 5A38 • 5A45 • 5B10N • 5B12N • 7A15 • 7A16A • 7A18 • 7A19 • 7A24 • 7A26 • 7B10 • 7B15 • 7B50 • 7B51 • 7B52 • 7B53A • 7B50A • 7B70 • 7B71 • 7B80 • 7B85 • 7B87 • 7B92 • 7B92A • 7D01 • 7D12 • 7D15 • 7J20 • 7S12 • 7T11 • 7T11A • AF501 • AM502 • AM503 • DC502 • DC503 • DC504 • DC505 • DM501 • DM502 • FG501 • FG501A • FG502 • FG503 • FG504 • FG507 • PG501 • PG502 • PG505 • PG506 • PG506A • PG508 • TG501 • SC502 • SC503 • SC504

Rear interface

The DM501 has a rear input, selectable by a front-panel button, on B28 (Hi) / A29 (Lo), and digit-serial BCD outputs (TTL), see below. The manual does not specify a limit to the input voltage on the rear interface but since this uses card-edge pins adjacent to logic output pins, sticking to the the DM501A specification (200 V peak / 100 V RMS) appears prudent.

Internals

The DM501 is precise to 4½ digits, but not accurate to 4½ digits. The combination of an ADC built from opamps and discretes combined with a noisy high-frequency isolated power supply make for barely achievable 3½ digit accuracy over all ranges. Every TM500 DVM after the 501 (including the DM501A, the DM502, and so on) used integrated A-to-D converters and a mains-frequency isolated power supply.

Pictures

  • DM501

    DM501

  • DM501 open left side

    DM501 open left side

  • DM501 integrator board

    DM501 integrator board

  • Two late DM501s with modified integrator boards

    Two late DM501s with modified integrator boards

  • DM501 integrator board solder side

    DM501 integrator board solder side

  • DM501 rear interface

    DM501 rear interface

Components

Some Parts Used in the DM501

Part Part Number(s) Class Description Used in
307-1015-00 307-1015-00 Discrete component resistor network DM501
Fairchild 3814 156-0306-00 Monolithic integrated circuit 4½ digit dual-slope DVM controller 7A13 • 7L13 • 7L18 • DM501