GQ GMC-300S
A basic, cheap beta-gamma counter for checking background levels and hobby samples. Buy it to learn, not for emergencies.
Amazon $55.98$55.98
GM tube132 CPM/µSv/h328 µSv/h
2.6/5
A cheap combined radiation and EMF meter for casual checks around the house. It is not a precise radiation instrument.
- GM tubeDetector
- β γ XDetects
- 80 CPM per µSv/h (Co-60)Sensitivity
Check price at Amazon$79.99
Price checked November 8, 2026. As an Amazon Associate we earn from qualifying purchases.
Pros
- Also measures electric and magnetic fields from appliances
- Light at 141 g
- Reads beta, gamma and X-rays
Cons
- Low sensitivity for a GM tube
- Keeps only alarm records, not a reading log
- Warranty term not published
How it scores
The rating comes from 6 measured or published factors, each scored 0-100 against fixed reference points for its detector type. How we rank explains each one.
Specifications
| Model number | GC-03 |
|---|---|
| Detection | |
| Detector | GM tube |
| Tube or crystal | J321 / M4011 GM tube |
| Radiation types | β γ X |
| Sensitivity | 80 CPM per µSv/h (Co-60) |
| Energy range | 48 to 1,500 keV |
| Gamma spectrum | No |
| Features | |
| Data logging | No |
| Connection | None |
| Battery | 1500 mAh rechargeable lithium |
| Build | |
| Weight | 141 g |
Alternatives in this detector type
GQ GMC-320 Plus
A long-running data-logging Geiger counter for steady background monitoring at a desk. The GMC-800 costs about the same and publishes more.
Amazon $97$97
GM tube328 µSv/h
Mazur PRM-7000
A rugged, long-running beta-gamma survey meter for people who want an instrument-grade build. Most home users get more for the money elsewhere.
Amazon $449$449
GM tube45 CPM/µSv/h5,000 µSv/h
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