Product Overview
Amperex XP 2202 B Photomultiplier Tube, 51 mm Bialkali Window, Unused in the Original Carton
Condition
Unused, New Old Stock. The glass envelope carries its original orange Amperex screen printing, reading Amperex, XP 2202 B, and MADE IN FRANCE, plus the marking 85-34 printed twice on the envelope and consistent with the mid-1980s vintage recorded for this stock. The blue 14-pin base is clean and undamaged, with pin numbers molded into the plastic and a center guide post; the pins are straight and carry no solder. The upper end of the envelope wears its factory black coating, with light surface scuffing from decades of shelf storage. The tube photographed came out of an original Amperex kraft electron tube carton labeled XP 2202 B / 22076, photographed with a loose stockroom parts tag resting on the box (P.O. 204934, part no. 0252105, quantity 1, "Tube assy. X2202B", WINCO 30-4656) and a black PHYSICAL INVENTORY 1995-6 sticker on the end label. Handled with gloves for the photos. Not powered up or tested here; five pieces in stock, and the photos show the one tube and carton described here.
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Product Overview
The Amperex XP 2202 B is a large-area photomultiplier tube built around a bialkali photocathode optimized for visible light, behind an active window of 51 to 52 mm (2 inches). Ten focused dynodes give a typical gain near 1,000,000 at an operating voltage of 1,100 to 1,500 volts, with dark current running about 3 nanoamps typical and 50 nA maximum, and dark counts about 300 per second typical against a 1,000 cps ceiling. Connection is through a standard 14-pin base, here a blue molded base with numbered pin positions and a center guide post, and the whole assembly is rugged glass and metal construction made in France. Through the clear section of the envelope you can see the copper-colored dynode cage and its support structure, which is exactly the part of a photomultiplier that decides how it behaves. Cross-referenced in old stockroom paperwork as XP2202B and as WINCO 30-4656.
Key Features
- Photocathode: bialkali, optimized for the visible spectrum
- Active window: 51 to 52 mm diameter (2 inches)
- Dynode chain: 10 focused dynodes
- Typical gain: about 1,000,000
- Operating voltage: 1,100 to 1,500 volts
- Dark current: about 3 nA typical, 50 nA maximum
- Dark counts: about 300 cps typical, 1,000 cps maximum
- Base: standard 14-pin, blue molded with numbered pins and center guide post
- Envelope markings: Amperex, XP 2202 B, MADE IN FRANCE, 85-34
- Build: rugged glass and metal construction, made in France
Applications
- Nuclear instrumentation technician rebuilding a scintillation counter that was designed around a 2-inch bialkali photomultiplier
- University physics lab assembling a Cherenkov or cosmic-ray detector and needing a known 10-stage tube for the head
- Spectroscopy engineer keeping a legacy fluorimeter running by putting a spare detector on the shelf before the old one fails
- Photon-counting experimenter setting up a dark box and high-voltage divider for low-light measurement work
Frequently Asked Questions
What do the markings 85-34 and 22076 mean?
85-34 is screen printed twice on the glass envelope in the factory orange ink, and 22076 is printed on the carton end label under the part number. We read them as factory markings, and 85-34 lines up with the mid-1980s stock date carried on this listing. Beyond what is printed, the coding is not confirmed here, so treat those numbers as identification rather than as a specification.
Has this tube been powered up or tested?
No. Testing a photomultiplier properly takes a dark box and a stable high-voltage supply, and we do not do that here. It is offered as unused New Old Stock on the strength of its markings, its unsoldered pins, and its original packaging. Original factory test sheets are included when available.
Does it come with a socket or a voltage divider?
No. You get the tube itself with its 14-pin base, as photographed. A socket, divider network, magnetic shield, and housing are not included, and the pin assignments are not confirmed by us, so check the XP 2202 B data sheet against your divider before you apply high voltage.
What voltage does it want?
The operating range on this tube is 1,100 to 1,500 volts for a typical gain around 1,000,000. Start low, bring the supply up gradually in a dark enclosure, and watch dark current before you trust any measurement.
It is unused, but it is forty years old. What am I actually taking on?
Straight answer: you are getting a tube that was never installed, still wearing its factory printing and its stockroom paperwork, but one that we have not lit up. We cannot promise the photocathode sensitivity it left France with, and no dark-current or gain numbers here are ours; they are the published figures for the type. What you can rely on is the photographs, which are the real spec sheet for this piece: the glass, the printing, the black end coating and its scuffs, the clean unsoldered pins, the carton and the 1995-6 inventory sticker are all shown up close. We have five of these in stock. If it is not right when it lands, our no-hassle satisfaction guarantee covers you. This one clears the free-shipping line on its own, and orders leave the Idaho warehouse the same or next business day.
Screen printed in France in the mid-1980s, counted once in somebody's 1995 inventory, and still waiting to see its first photon. Give it a dark box and a clean high-voltage rail, and the next flash it catches belongs to you.
