Specialized - Photo Tube ·Photomultiplier
1P21
RCA 1P21 nine-stage side-on photomultiplier tube with S-4 cesium-antimony photocathode, peak spectral response near 400 nm and high gain for low-light detection.
- Sections
- 1
- Base
- -
- Socket code
- -
- Base pins
- 11
- Nominal heater
- -
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- -
- Socket code
- -
- Base pins
- 11
- Nominal heater voltage
- -
- Nominal heater current
- -
- Parallel heater voltage
- -
- Parallel heater current
- -
- Series capable
- No
Terminal pinout
Electrical assignments shared by every tube using this base designation.
No verified pinout is recorded for this base designation.
Section ratings
1 physical section, each with unique specifications.
Section 1
Photomultiplier
- Max plate voltage
- 1250 V
RCA 1P21 nine-stage S-4 side-on photomultiplier. Anode-cathode supply max 1250 V DC or peak AC, anode-to-dynode9 max 250 V, each consecutive dynode gap max 250 V, dynode1-cathode max 250 V. Average anode current maximum 0.1 mA (this is output anode current, NOT cathode current); peak anode current maximum 1 mA (1949 data). Current amplification ~2,000,000 at 100 V per stage; ~300,000 at 75 V/stage and 50 V last gap. Typical luminous anode sensitivity 80 A/lm at 100 V/stage, 12 A/lm at 75 V/stage; minimum 40 A/lm at 100 V/stage (1949). Peak spectral response 400±50 nm, S-4 cesium-antimony photocathode. Anode-dynode9 capacitance ~4–4.4 pF, anode-to-all ~6–6.5 pF. No heater; maximum ambient +75 °C.
Source-dependent data
Operating conditions by source
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.