Supported Applications
The HH303 is a low-cost, pocket-sized handheld thermometer built around Type J/K thermocouple inputs, giving technicians a portable, high-accuracy way to measure temperature almost anywhere. A 4-digit LCD shows readings in Celsius or Fahrenheit at the press of a button, and the dual-input design supports a T1-T2 differential display for comparing two points directly.
Standard features such as min/max and average readings, reading hold, and a relative mode make it well suited to HVAC service, laboratory and QA work, food and equipment monitoring, and general field troubleshooting. Each unit ships complete with a beaded-wire Type K thermocouple (one per input), a 9V battery, an operator's manual, and a NIST certificate (no points).
What sets the HH303 apart in the HH300 family is data connectivity: it offers a USB or RS232 interface option so measurements can be logged and read on a PC, turning a simple handheld into a datalogging tool for trend capture and record-keeping.
Operating Conditions & Performance
The HH303 measures across a wide thermocouple range and updates the display quickly. Key performance figures include:
• Type K range: -200 to 1370°C (-328 to 2498°F)
• Type J range: -200 to 760°C (-328 to 1400°F)
• Accuracy: 0.1% rdg + 0.7°C (1.4°F)
• Resolution: 0.1°C/0.1°F up to 599.9°C/999.9°F
• Input protection: 60 Vdc or 24 Vrms AC maximum
For T1-T2 differential measurement, accuracy is ±(0.2% T1-T2 reading + 1.7°C) or ±(0.2% T1-T2 reading + 3.4°F); note that the basic accuracy specification does not include probe error. The meter runs on a 9V battery (MN 1604) for up to 120 hour with alkaline cells, operates from 0 to 40°C (32 to 104°F) at <80% RH, and stores from -10 to 60°C (14 to 140°F). It weighs approximately 200 g (7 oz), measures 184 H x 64 W x 30 mm D (7.5 x 2.5 x 1.2"), is CE marked, and carries a 1 YEAR WARRANTY.
Configuration Options
The HH303 accepts both Type K and Type J thermocouples on each channel, and the measuring capability changes with the type selected — Type K reaches -200 to 1370°C (-328 to 2498°F), while Type J spans -200 to 760°C (-328 to 1400°F). Both retain the same 0.1% rdg + 0.7°C (1.4°F) accuracy and 0.1°C/0.1°F resolution.
Beyond the meter itself, capability is extended through interface and power options. PC connectivity can be configured as an RS232 link (software and cable) or as a USB link (software driver and cable), and continuous bench use is supported by an optional AC adaptor. Spare RS232 and USB interface cables are also available so a single HH303 can be adapted to different logging setups.
Key Product Differences
The series centers on one meter with a set of matching interface and service options:
• HH303 — Type J/K handheld 0.1°C/F thermometer
• HH310-SW — Software and RS232 interface cable for HH303
• HH300-SW-USB — Software driver and USB interface cable for HH303 (requires HH310-SW)
• HH300-ADAPTER — AC adaptor for HH303
• HH300-CABLE — Spare RS232 interface cable for HH303
• HH300-CABLE-USB — Spare USB interface cable for HH303
• CAL-3-HH — NIST-traceable calibration, with points
A free Type K insulated beaded-wire thermocouple with subminiature connector and wire spool caddy is included (one per channel); spares can be ordered as model SC-GG-K-30-36.
- Dual Input
- Dual Display
- 4 digit LCD
- MAX, AVG, MIN, HOLD, REL Function
| Additional Features 1 | MIN/MAX/AVG/REL/HOLD Functions , Auto Power-Off |
| Battery life | 120 hr |
| Battery Size and Type | Alkaline 9V |
| Data Interface | USB, RS232 |
| Display Type | LCD |
| Display Type Note | 4-digit LCD |
| Height | 30 mm |
| Input Protection Voltage | 60Vdc/24Vrms |
| Length | 184 mm |
| Measurement Type | Temperature |
| Number of Measurements | 2 |
| Operating Temperature, Max | 40 °C |
| Operating Temperature, Min | 0 °C |
| Relative Humidity, Max | <80% |
| Series ID | HH300-303 |
| Storage Temperature, Max | 60 °C |
| Storage Temperature, Min | -10 °C |
| Supply Power Type | Battery |
| Temperature Accuracy | ± 0.7 °C |
| Temperature Accuracy Note | 0.1% rdg + 0.7°C (1.4°F) |
| Temperature Measurement, Max | 1370 °C |
| Temperature Measurement, Min | -200 °C |
| Temperature Resolution | ± 0.1 °C |
| Temperature Resolution Note | 0.1°C/0.1°F up to 599.9°C/999.9°F |
| Temperature Sensor Type | Thermocouple |
| Weight | 200 g |
| Width | 64 mm |