eBay

FOR SALE lot of 1 pc. Well known tiny SBM-21 Geiger counter tube.

All tubes are tested working well. New old stock.

Parcel will be well packed and shipped by air mail with tracking number, shipping usually takes 12-21 days, depends on your location.

If you need more tubes than listed or other type of devices please send me a message.

SBM-21 Geiger Counter Tube Technical Specifications:

⚙️ Technical Specifications

Parameter	Specification
Measuring Range	0.1 … 1000 µR/sec
Maximum Counting Rate	≤ 650 pulses/sec
Gamma Sensitivity (Cs‑137)	6.5 … 9.5 pulses/sec at 10 µR/sec
Working Voltage	350 … 475 V
Start of Counting Voltage	260 … 320 V
Plateau Length	≥ 100 V
Pulse Amplitude	≥ 50 V
Plateau Slope	≤ 0.15 % / V
Dead Time (at 400 V)	64 µsec
Background Noise	≤ 0.2 pulses/sec
Tube Diameter	~6 mm
Tube Length	~21 mm
Weight	~0.8 g

These specifications are standard for this miniature GM tube and used for gamma/beta radiation detection. Soviet-Tubes+1

✅ Features & Benefits

✔ Compact and lightweight for small portable devices
✔ Low background noise for accurate measurements
✔ Wide voltage operating range
✔ Compatible with many DIY and industrial Geiger counter projects
✔ Carefully tested and ready to use

📦 What You Will Receive

1 × SBM‑21 Geiger Counter Tube
Protective packaging

🚚 Shipping & Handling

Ships within 1–2 business days
Carefully packed to avoid damage
Worldwide shipping available

🔁 Returns

Returns accepted if the item is not as described.

Please contact the seller before returning.