When engineers and instrumentation technicians need reliable portable process calibrators for workshop bench testing, or live plant environments, Instrotech's locally designed and manufactured Calog calibrators range, including the 4-20mA Loop Calibrator, delivers. Built around modern component technology, an intuitive interface, and a rugged IP54-rated housing, the Calog series is engineered for the demands of real industrial field calibration work.

Common Features Across the Calog Calibrator Range

All Calog calibrators offer a consistent set of key features, providing the same practical tools for engineers regardless of the specific model:

• Key-per-digit numeric entry for fast source value setup - scroll each digit independently up or down without cycling through the full range.
• 128 x 64 backlit LCD display - switchable between numeric or trending views with programmable timing.
• Data-logging via SD card or USB - download to a PC and open in spreadsheet software.
• Compact and rugged - 86 x 155 x 43 mm, IP54 rated for dust and splash resistance.
• Lithium-Ion battery with approximately 8 hours of run time (measured and sourced combined), with temperature sensing built in.
• Programmable auto-off and selectable date/time settings.
• Standard accessories included: battery charger, carry case, non-slip rubber cover, and safety leads.
• 2-year guarantee against faulty materials and workmanship.

Calog-TEMP: Portable Temperature Calibrator

The Calog-TEMP is a high-precision, multifunctional temperature calibrator that handles the full range of temperature measurement and sourcing tasks in a single handheld device. It measures milliamps, millivolts, thermocouples, ohms, and RTDs simultaneously — with temperature channels isolated from the mA channel so both can be displayed at the same time.

This makes field and workshop calibration straightforward: inject thermocouple millivolts (or RTD ohms) into a transmitter while reading the mA output, all from one instrument.

Supported thermocouple types: K, T, B, R, S, E, N, U, L.
Supported RTD types: Pt50, Pt100, Pt200, Pt500, Pt1000, Ni100, Ni120.

The cold junction compensation is automatic (internal), or can be set manually or via an external reference. Ohm and RTD measurements support 2-, 3-, or 4-wire connections; sourcing is in 2-wire form. The mA measurement is selectable between passive and active (with 24 V loop power for 2-wire transmitters).

A plug-in extender with spring terminals is included for direct connection to bare thermocouple wires or compensating cables — the cold junction correction is integrated into the extender itself. The graphic display can be switched to trend logging mode, making it a useful tool for monitoring ovens or tuning PID controllers.

Calog-LOOP II: Portable mA Loop Calibrator

First launched in 2005 as the original Calog product, the Calog-LOOP II is now in its second generation, rebuilt around an ARM processor for improved performance and expanded features, including data-logging and SD card storage.

This instrument is purpose-built for milliamp loop-powered instrumentation. It measures, sources, and simulates 4–20 mA signals with an accuracy of 0.01% full scale (0–24 mA input range) and 0.005% full scale for 0–32 V inputs. Sourcing modes include increment, step, ramp, and valve stroking — useful for commissioning and fault-finding on control valves and transmitters. DC voltage (0–32 V) and circuit continuity measurement are also included.

Display options include mA and percent simultaneously. Where loop power is needed, 24 V excitation is available onboard. Trend logging with a programmable time base is available for long-term loop monitoring, with data stored on the SD card and easily exported via USB to a PC spreadsheet.

Calog-PRESSURE II: Portable Pressure Calibrator

The Calog-PRESSURE II is a second-generation portable pressure calibrator that combines pressure measurement with the full capabilities of an mA loop calibrator — making it a single instrument for pressure transmitter calibration, I/P converter testing, and general loop maintenance.

Pressure sensing uses Keller PA-33x series digital pressure sensors, connected via a Binder connector for easy swap-out. The calibrator can simultaneously measure pressure and milliamps, or source milliamps while measuring pressure, depending on the task:

• Pressure transmitter calibration: measure pressure and mA output simultaneously.
• I/P converter testing: source mA and measure the resulting pressure.
• Emergency replacement mode: enable TRACKING so the mA output follows the measured pressure — effectively placing the calibrator in-circuit as a temporary pressure transmitter, useful for data-logging or maintaining control during instrument downtime.

It also measures DC voltage, circuit continuity, and milliamps, and can source and simulate mA signals for loop maintenance work.

Calog-LC II: Portable Load Cell Tester and Calibrator

The Calog-LC II is Instrotech's most feature-complete portable calibrator, designed specifically for strain gauge load cell testing, diagnostics, and calibration. It supports indication and data logging via USB or an SD card.

Field Testing Without Removing Load Cells

A key benefit of the Calog-LC II is in situ load cell testing—no need to remove the load cells. Test each cell and get a diagnostic readout in under ten seconds.

The automated test sequence:

1. Detects whether the wiring is 4-wire or 6-wire (3- or 5-wire results flag a fault condition).

2. Verifies all connections are sound.

3. Powers up the load cell and measures no-load mV for bridge balance.

4. Measures resistance through the strain gauge bridge — input, output, and balance — in sequence.

5. Performs an insulation test at 50 V (measured in MΩ) to detect water ingress, with low readings highlighted onscreen.

If a load cell has been overloaded, the zero balance will be out of spec. Water penetration shows up in the insulation test. The full result is summarised on the backlit graphic display.

Indication and Calibration

To show units, set sensitivity, range, decimal, and units. Zero trim for deadweight, span trim for accuracy. Tare and other functions are included.

Supports one 350 Ω load cell or up to three 1000 Ω cells (5 V excitation).

For load cell amplifier calibration, inject a known mV value via the 4 mm sockets and measure the corresponding mA output simultaneously. The mA measurement is isolated from the mV source to prevent ground loops. Alternatively, enter the sensitivity and range, set a target mass value, and the calibrator calculates and outputs the correct mV equivalent — or vice versa.

The Calog-LC II can also simulate a load cell transmitter by sourcing mA directly into a display or SCADA system, with the output configurable in mA or scaled to mass units.

Contact INSTROTECH to learn more about The Calog Calibrator range,  available from Instrotech. Each model addresses a specific calibration discipline while sharing the same rugged, field-proven platform — making it practical to standardise on the range across maintenance and instrumentation teams.