1. Introduction
The FNIRSI GC-03 is a versatile 3-in-1 detector designed for comprehensive environmental and pollution monitoring. This professional instrument utilizes a 2.4-inch high-definition color screen to provide real-time monitoring of Nuclear Radiation (NR), Electric Field (EF), and Magnetic Field (MF). It is suitable for various applications including home, office, and outdoor environments.

Image: FNIRSI GC-03 3-in-1 Radiation Detector with display showing readings for EF, MF, and Nuclear radiation.
2. Package Contents
Upon opening your FNIRSI GC-03 package, please ensure all the following items are present:
- GC-03 Host (Main Unit) x 1
- Packing Box x 1
- User Manual x 1
- Data Cable (Type-C) x 1

Image: Visual representation of the GC-03 package contents.
3. Product Features
The FNIRSI GC-03 detector is equipped with advanced features to provide accurate and user-friendly environmental monitoring:
- 3-in-1 Detection: Simultaneously measures Nuclear Radiation (NR), Electric Field (EF), and Magnetic Field (MF).
- Real-time Monitoring & Alarm: Continuously displays measured values and their units, evaluating danger levels based on user-defined alarm thresholds.
- Flexible Radiation Unit Settings: Allows selection of various radiation measurement units including μSv/h, μGy/h, mR/h, CPS, and CPM.
- Alarm Record Function: Stores a history of up to 50 alarm events, including the data type (NR/EF/MF) and the exact date and time of the trigger.
- Multiple Alarm Modes: Features customizable alarm modes including indicator light, vibration, and audible alerts, which can be combined as per user preference.
- High-Precision Geiger Counter Tube: Utilizes an energy compensation GM tube (Geiger counter tube) for precise detection with high sensitivity and low power consumption.
- Dynamic Curve Mode: Visualizes changes in radiation levels over time, allowing for deeper analysis.
- Smooth Rotary Knob Control: Intuitive rotary knob for easy navigation and function switching.
- Dual Theme Design: Offers Day & Night clarity with a 2.4-inch vibrant color screen, ensuring clear readings in any lighting condition.






4. Specifications
| Parameter | Specification |
|---|---|
| Brand Name | FNIRSI |
| Model Number | GC-03 |
| Certification | CE |
| Origin | Mainland China |
| Electronic | Yes |
| Battery Included | Yes |
| High-concerned chemical | None |
| Screen Material | 2.4-inch color screen |
| Backlight | Brightness adjustable |
| Charging Power | TYPE-C (5V/1A) |
| Battery | 1500mAh |
| Languages | Chinese/English |
| Product Size | 138x63x32mm |
| Product Weight | 141g |
Measurement Parameters
| Measurement Type | Units | Accuracy | Range |
|---|---|---|---|
| Nuclear Radiation (NR) | μSv/h | 0.01μSv/h | 0.01μSv/h - 999.99μSv/h |
| Electric Field (EF) | V/m | 1V/m | 1V/m - 1999V/m |
| Magnetic Field (MF) | μT | 0.01μT | 0.01μT - 99.99μT |
| Power Density (for EMF) | mW/m² | N/A | 0.2 - 1000mW/m² |
Nuclear Radiation (NR) Detection Specifics
| Parameter | Specification |
|---|---|
| Detection Radiation Type | Ionizing radiation (gamma rays, X-rays, Hard β rays) |
| Detector | Energy compensation GM tube (Geiger counter tube) |
| Dose Current Rate | 0.00 - 10000μSv/h (10mSv/h) |
| Cumulative Dose Equivalent | 0.00μSv - 500.0mSv |
| Energy Range | 48keV - 1.5MeV ≤ ±30% (for 137Cs-) |
| Sensitivity | 80CPM/μSv |
| Dose Unit | μSv/h, μGy/h, mR/h, cps, cpm |
| Alarm Mode | Light, vibration, sound |
5. Setup Guide
5.1 Charging the Device
Before first use, fully charge your GC-03 detector using the provided Type-C charging cable. Connect the cable to the device's Type-C port and a compatible 5V/1A power source. The battery indicator on the screen will show charging status.
5.2 Powering On and Language Selection
- Hold down the power button located on the side of the device. The device will instantly wake up and display the FNIRSI logo.
- Upon initial startup, you will be prompted to select your preferred language (Chinese/English). Use the navigation buttons or rotary knob to select 'English' and confirm.
5.3 Initial Inspection
After powering on, briefly check the display for any abnormalities. The device should show initial readings for Radiation, Electric, and Magnetic fields. Ensure the Geiger tube is visible and appears intact through the transparent section of the device.

Image: Comparison of GC-01, GC-02, and GC-03 models, showing GC-03's advanced features.
6. Operating Instructions
6.1 Navigating Modes
The GC-03 offers three smart modes for flexible monitoring, easily switchable with the intuitive rotary knob:
- Quick View Mode: Provides a triple-screen display with clean, easy-to-read data for immediate monitoring.
- Professional Mode: Offers more detailed information and advanced settings for in-depth analysis.
- Graph Mode (Dynamic Curve Mode): Visualizes changes in radiation levels over time, displaying a dynamic curve and tracking up to 50 alarm history sets.

Image: Three Smart Modes for Flexible Monitoring.
6.2 Customizing Alarm Thresholds
You can customize alarm thresholds for both radiation and EMF levels. Navigate to the 'Alarm Set' option in the settings menu. Here, you can adjust the desired alarm values for current dose and cumulative dose. The device will log each alert trigger time automatically in the 'Alarm Record' section.
6.3 Switching Units
The device allows you to switch measurement units for radiation and EMF independently. Access the 'Units Set' option in the settings menu to select your preferred units (e.g., μSv/h, μT, V/m).
6.4 Video Demonstration
Watch this official video for an unboxing and demonstration of the FNIRSI GC-03's features and operation:
Video: Unboxing and demonstration of the FNIRSI GC-03 detector, showing its features and user interface.
7. Wide Applications
The FNIRSI GC-03 is designed for a broad range of applications where monitoring of nuclear radiation, electric fields, and magnetic fields is crucial:
- Home Appliances: Checking radiation from microwaves, refrigerators, air conditioners, washing machines.
- Electronic Equipment: Monitoring emissions from laptops, TVs, game consoles, and other electronic devices.
- Building Materials: Assessing radiation levels in construction materials.
- Medical Environment: Detecting radiation in medical settings (e.g., near CT scanners).
- Nuclear Power Plants: Environmental monitoring around nuclear facilities.
- Import & Export Goods: Screening for radiation in goods.

Image: Examples of wide applications for the GC-03 detector.
8. Maintenance
To ensure optimal performance and longevity of your GC-03 detector, follow these maintenance guidelines:
- Cleaning: Use a soft, dry cloth to clean the device. Do not use abrasive cleaners or solvents.
- Storage: Store the device in a cool, dry place, away from direct sunlight, extreme temperatures, and high humidity.
- Handling: Avoid dropping or subjecting the device to strong impacts.
- Battery Care: For long-term storage, charge the battery to about 50-70% and recharge every few months to prevent deep discharge.
9. Troubleshooting
If you encounter any issues with your FNIRSI GC-03 detector, please consider the following common solutions:
- Device Not Powering On: Ensure the device is fully charged. Connect it to a power source using the Type-C cable and allow it to charge for at least 30 minutes before attempting to power on again.
- Inaccurate Readings: Ensure the device is operating within its specified environmental conditions (temperature, humidity). Avoid strong electromagnetic interference sources nearby. If readings remain consistently abnormal, try restarting the device.
- Display Issues: If the screen is unresponsive or shows glitches, try restarting the device. If the issue persists, ensure the device has sufficient battery.
- Alarm Not Triggering: Check the 'Alarm Set' menu to ensure thresholds are correctly configured and the alarm modes (light, vibration, sound) are enabled as desired.
For persistent issues not resolved by these steps, please contact customer support.
10. Warranty and Support
Thank you for choosing FNIRSI. Our products undergo strict quality inspection before being sent out. We are committed to providing high-quality products and excellent customer service.
- Quality Assurance: All FNIRSI products are subject to rigorous quality control.
- Free Returns: Enjoy free returns within 90 days of purchase.
- Contact Support: If you have any questions, need assistance, or encounter any issues with your product, please contact FNIRSI customer support. Refer to the contact information provided in your purchase documentation or on the official FNIRSI website.
11. Safety Information
Please read and adhere to the following safety guidelines to ensure safe and proper use of your FNIRSI GC-03 detector:
- Always operate the device according to the instructions provided in this manual.
- Do not attempt to disassemble, modify, or repair the device yourself. This may void the warranty and could lead to electric shock, fire, or other hazards.
- Keep the device away from water, flammable liquids, and explosive environments.
- Avoid exposing the device to extreme temperatures, high humidity, or direct sunlight for prolonged periods.
- This device is not a medical instrument and should not be used for medical diagnosis or treatment.
- Keep out of reach of children.
- Dispose of the device and its battery responsibly according to local environmental regulations.





