eBay

FOR SALE lot of 10 pc. Well known SBM-20 Geiger counter tube.

All tubes are tested working well. New old stock.

Some tubes may have some light dents that do not effect their work.

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

SBM-20 Geiger Counter Tube Technical Specifications:

⚙️ Technical Specifications

🔌 Electrical Characteristics

Parameter Value
Minimum Anode Resistor 1.0 MΩ
Recommended Anode Resistor 5.1 MΩ
Recommended Operating Voltage 400 V
Operating Voltage Range 350 – 475 V
Initial (Starting) Voltage 260 – 320 V
Plateau Length ≥ 100 V
Maximum Plateau Slope 10 % per 100 V
Minimum Dead Time (at 400 V) 190 µs

Parameter	Value
Minimum Anode Resistor	1.0 MΩ
Recommended Anode Resistor	5.1 MΩ
Recommended Operating Voltage	400 V
Operating Voltage Range	350 – 475 V
Initial (Starting) Voltage	260 – 320 V
Plateau Length	≥ 100 V
Maximum Plateau Slope	10 % per 100 V
Minimum Dead Time (at 400 V)	190 µs

📊 Sensitivity & Measurement Range

Parameter Value
Working Range 0.004 – 40 µR/s
Working Range 0.014 – 144 mR/h
Gamma Sensitivity (Ra-226) 29 cps / mR/h
Gamma Sensitivity (Co-60) 22 cps / mR/h
Inherent Background Count ~1 cps

Parameter	Value
Working Range	0.004 – 40 µR/s
Working Range	0.014 – 144 mR/h
Gamma Sensitivity (Ra-226)	29 cps / mR/h
Gamma Sensitivity (Co-60)	22 cps / mR/h
Inherent Background Count	~1 cps

🧱 Physical Characteristics

Parameter Value
Gas Filling Ne + Br₂ + Ar
Cathode Material Stainless steel, 50 µm
Tube Capacitance 4.2 pF
Wall Thickness 0.05 mm
Areal Density 40 mg/cm²

Parameter	Value
Gas Filling	Ne + Br₂ + Ar
Cathode Material	Stainless steel, 50 µm
Tube Capacitance	4.2 pF
Wall Thickness	0.05 mm
Areal Density	40 mg/cm²

📐 Dimensions & Weight

Parameter Value
Maximum Length 101 mm
Effective Length 83.5 mm
Maximum Diameter 11 mm
Effective Diameter 10 mm
Connector Type Pin
Weight 9 g

Parameter	Value
Maximum Length	101 mm
Effective Length	83.5 mm
Maximum Diameter	11 mm
Effective Diameter	10 mm
Connector Type	Pin
Weight	9 g

🌡️ Environmental & Lifetime Characteristics

Parameter Value
Operating Temperature Range −60 °C to +70 °C
Expected Lifetime ≥ 2 × 10¹⁰ pulses

Parameter	Value
Operating Temperature Range	−60 °C to +70 °C
Expected Lifetime	≥ 2 × 10¹⁰ pulses

✅ Features & Benefits

✔ Very low background count

✔ Stable and wide voltage plateau

✔ Long service life

✔ Compact size

✔ Ideal for portable and DIY Geiger counters

📦 What You Will Receive

1 × SBM-20 Geiger Counter Tube

Secure protective packaging

🚚 Shipping

Fast dispatch (1–2 business days)

Carefully packed to prevent damage

Worldwide shipping available

🔁 Returns

Returns accepted if the item is not as described.
Please contact the seller before returning.