Glow Transfer Counting Tubes

Glow transfer counting tubes, commonly known as dekatrons, are cold-cathode decimal counting devices. Dekatrons pass an ionization glow around a ring of cathodes by sending a single or offset double or triple pulse to intermediate guide electrodes, causing the glow to advance to the next cathode. Though a few dekatrons were manufactured with speeds as fast as 1MHz, most were used for applications below 100kHz. Dekatrons double as both counter and display; the count position is viewable through the top of the tube as a glowing dot. This combination of display and computation in a single component would not be replicated in a solid state device until the introduction of intelligent LED displays in the 1970s.

Dekatrons come in three basic types: counters, computer counters and selectors. Counters have a single output cathode, which is pulsed once per full rotation. Computer counters have multiple output cathodes, usually four. Selectors have 10 output cathodes. Contrary to popular misconception, dekatrons were not widely implemented in computers. Only one computer is known to have made significant use of dekatrons, the AERE WITCH. Completed in 1950, each of the WITCH's memory stores contained 90 GC10A dekatron tubes; the WITCH was a major consumer of Ericsson dekatrons until it was decommissioned in 1973.

The world's first production glow transfer counting tube, the short-lived GC10A, was filled with helium, but all other early and common British and US dekatrons are 4kHz neon-filled devices. Faster dekatrons, in the 10-50 kHz range, are usually filled with argon or a helium-hydrogen mix, popular among hobbyists for the distinctive purple glow. Dekatrons rated at 100 kHz appear to be filled with some sort of Penning mixture which exhibits improved ionization characteristics, allowing for higher counting speeds. A small handful of dekatrons operate at 1MHz; such tubes use hydrogen as the fill gas and typically have shaped cathodes and other internal complexities.

While most dekatrons are decimal counters, there are also a few base-12 counters, a handful of unusually constructed Soviet base-10 dekatrons which can also function as base-5 counters, and one binary counter, which operates like a flip-flop.

Anod A-102 & A-103
 Anod A-102 & A-103

Devices included in this entry:

Anod A-102 selector (13-pin base; pictured in thumbnail)
Anod A-103 selector (13-pin base)


The Anod A-102 and A-103 are fairly typical helium-hydrogen filled double pulse selector dekatrons, descended from the original Soviet A-101 selector dekatron. While the A-101 is rated at only 1KHz, the A-102 and A-103 are rated at 20KHz and 50 KHz, respectively.

Soviet Dekatron Datasheet (PDF)

[View Detail]

Anod A-107 & A-108
 Anod A-107 & A-108

Devices included in this entry:

Anod A-107 selector (12-pin miniature base)
Anod A-108 selector (12-pin miniature base; pictured in thumbnail)


The Anod A-107 and A-108 are the smallest dekatrons ever commercially produced. Housed in a familiar IN-2 Nixie tube envelope, The A-107 and A-108 are even smaller than the legendary Elesta ECT100. The A-107 and A-108 have 10 shaped cathodes, and are capable of operating as a base-5 or base-10 device. All 10 cathodes are brought out to separate pins, allowing for great versatility in operation, though the shaped cathodes restrict the A-107 and A-108 to unidirectional counting. The A-107 can operate at an incredibly fast 1MHz, but a heavy silvering at the top of the envelope prevents direct viewing of the count position. The A-108 is directly viewable, but contains a different fill gas and is only capable of 10KHz operation.

Anod also manufactured the A-109, structurally identical to the A-108 but containing a different fill gas which permits counting speeds up to 100KHz.

Soviet Dekatron Datasheet (PDF)

[View Detail]

Anod OG-3
 Anod OG-3

The Anod OG-3 is a commonly available single pulse counter dekatron with an extra output cathode, rated at 20KHz. The OG-3 has a helium-hydrogen fill, and is available in both metal and phenolic base variants.

Soviet Dekatron Datasheet (PDF)

[View Detail]

Anod OG-x Series
 Anod OG-x Series

Devices included in this entry:

Anod OG-4 counter (octal base)
Anod OG-7 counter (octal base)
Anod OG-9 computer counter (octal base; pictured in thumbnail)


The Anod OG-4 is a fairly standard 2KHz double pulse counter dekatron with a neon fill gas. The OG-7 is internally identical to the OG-4, but has a gas mixture resembling helium-hydrogen and a respectable counting speed of 50KHz. The OG-9 is a computer counter variant of the OG-4 with multiple output cathodes. All devices in this series were manufactured in both metal and phenolic base variants.

Soviet OG-4 Datasheet

[View Detail]

ETL GC10/A
 ETL GC10/A

Introduced in 1949, the ETL GC10/A counter is the world's first commercially manufactured dekatron. The GC10/A is a double pulse, two guide, 10 position device, housed in what would become the standard elongated envelope of many later Ericsson dekatrons. Internally, the GC10/A is very different from later devices, with a helium fill gas and primitive internal construction consiting of an elaborate framework of metal rings and mica supports. The GC10/A and subsequent GC10B established a basic plan which would be followed by most other dekatrons, the major exceptions being devices manufactured by Elesta and Western Electric. In contrast to the commonly available GC10B, the GC10/A is extremely rare. Most known examples of this device are currently installed in a single memory bank in the AERE WITCH computer.

[View Detail]

ETL GC10B & GC10/4B
 ETL GC10B & GC10/4B

Devices included in this entry:

ETL / Baird Atomic GC10B counter (octal base; pictured in thumbnail)
ETL GC10/4B computing counter (octal base)


The ETL GC10B, a highly revised version of the GC10/A, is a neon-filled double pulse counter rated at 4KHz. The GC10B is internally quite different from the GC10/A, abandoning a complex internal structure in favor of a simplified design with a ceramic cathode support.

Otherwise identical to the GC10B, the GC10/4B is a computing counter with four output cathodes. The pinout of the GC10/4B is a superset of the GC10B pinout.

ETL GC10B, GC10B/S Datasheet (PDF)

[View Detail]

ETL GC10/4C
 ETL GC10/4C

The ETL GC10/4C is a compact, electrically identical revision of the GC10/4B computer counter. Instead of the elongated envelope typical to earlier ETL dekatrons, the GC10/4C has a more standard length envelope, approximately 25% shorter than the GC10B and GC10/4B.

[View Detail]

ETL GC10D
 ETL GC10D

The ETL GC10D serves as the industry prototype for single pulse, three guide counter dekatrons. Devices which copy this basic plan include the Anod OG-3 and Rodan DK23. The GC10D, capable of 10KHz operation, has a fill gas consisting primarily of helium and is consequently extremely prone to outgassing.

ETL GC10D Datasheet (PDF)

[View Detail]

ETL GS10C/S
 ETL GS10C/S

The ETL GS10C is the selector equivalent of the GC10B counter dekatron. Like the GC10B, the GS10C is a double pulse two-guide device with a neon fill gas and a 4KHz maximum operating frequency. The GS10C/S pictured here is the military variant of the standard GS10C.

ETL GS10C/S Datasheet (PDF)

[View Detail]

ETL GS10H
 ETL GS10H

The ETL GS10H is a compact adaptation of the GS10C. Housed in a compact envelope, the GS10H has the traditional two-guide configuration with a neon fill gas, although it has a slightly higher speed rating of 5KHz. The GS10H has a 17-pin base, and is compatible with the 27-pin sockets used with Burroughs beam switching tubes.

[View Detail]

ETL GS12C
 ETL GS12C

The ETL GS12C is a base-12 version of the GS10C selector dekatron, equipped with a maintenance base. Like the GS10C, the GS12C is neon-filled with a 4KHz maximum counting speed.

[View Detail]

ETL GCA10G
 ETL GCA10G

The ETL GCA10G is a rare 'direct drive' counter dekatron, designed to be directly connected to a Nixie tube which displays the dekatron's count position. The GCA10G has ten supplemental anodes arranged inside the cathode ring and aligned to each output cathode. As the glow transfer moves around the cathode ring, current will move between the supplemental anodes and the primary anode, illuminating each character of the Nixie tube in sequence.

ETL also developed the GSA10G, a direct drive selector variant with improved anode geometry which isolates the glow transfer to a specific supplemental anode. Later examples of GCA10G also incorporate this improvement.

[View Detail]

Elesta EZ10
 Elesta EZ10

The Elesta EZ10 is the smallest and fastest nomotron ever manufactured. Capable of 50KHz operation, the EZ10 has 20 shaped cathodes and an argon fill. Unlike most nomotrons, the perforated screen above the cathodes has no numeral markings. The EZ10 design later evolved into the EZ10A and EZ10B dekatrons, which abandoned the nomotron screen and adopted a different internal wiring configuration.

[View Detail]

Elesta EZ10A & EZ10B
 Elesta EZ10A & EZ10B

Devices included in this entry:

Elesta EZ-10A selector (13-pin miniature base; pictured in thumbnail)
Elesta EZ-10B selector (13-pin miniature base)


Perhaps the best-known of Elesta's dekatron products, the EZ10A and EZ10B are miniature single-guide selector dekatrons with 20 shaped cathodes. The ten guide pins are ganged together in two groups of five, one on the left and one on the right side of the tube. This unsual arrangement allows the EZ10A and EZ10B to operate in base-10 or base-5 configurations. The EZ10A appears to be argon filled and is capable of 300KHz operation, but the structurally identical EZ10B is hydrogen filled and operates up to 1MHz. Although the EZ10A and EZ10B are pin-compatible, the higher voltage required for the EZ10B would damage an EZ10A.

[View Detail]

Elesta ECT100
 Elesta ECT100

The ECT100 is a 1MHz bidirectional hydrogen-filled selector with only 20 cathode positions. This seemingly impossible feat is accomplished by a highly innovative internal design in which both guides and cathodes are driven with pulse waveforms. The tube has four distinct cathode structures, each of which is arranged as a ring of five spade-shaped posts connected to a central disk. Two of the cathode structures are designated as output cathodes, and the other two are designated as guide cathodes. In operation, the two output cathodes are driven with alternating waveforms and the two guide cathodes are driven with slightly delayed signals from the output cathodes. By reversing the connections between the output cathodes and the guide cathodes, the rotation direction can be reversed, allowing for a complete bidirectional base-ten count operation to be carried out in a tube that has only 20 cathode positions.

With all of the ECT100's cathodes tied up as waveform inputs, a rather interesting method must be used to read the tube's state. Below each of the tube's output cathode spades is a forked sense anode, which projects upward around either side of the spade. When a given spade is ionized, the glow will exit from slits on either side of the spade, enveloping the sense anode. This causes a probe current to flow back through the anode, sensed on one of the ten output pins.

The ECT100's combination of speed, function, and size make it the most advanced dekatron ever made. Despite this, it was birthed into obsolescence, competing with the well-established beam switching tube and the introduction of small-scale integrated circuits. As a result, the ECT100 was narrowly implemented in its time, and is virtually nonexistant today.

[View Detail]

Mullard Z504S
 Mullard Z504S

The Mullard Z504S is a 4KHz double pulse selector dekatron in a compact envelope. Mullard also developed the Z505S, a 50KHz selector, structurally identical to the Z504S but with a Penning-type fill gas.

Z504S Datasheet (PDF)

[View Detail]

Plasma Labs A-201
 Plasma Labs A-201

The Plasma Labs A-201 is a 10KHz polyatron or 'inverse dekatron'. Instead of having a central anode surrounded by a ring of cathodes, polyatrons have a central cathode surrounded by a ring of anodes and a screen electrode. This arrangement prevents the cathode poisoning experienced in traditional dekatrons, but the polyatron structure prevents direct viewing of the count through the top of the tube. With an operational polarity like that of a beam switching tube, the A-201 can directly drive a Nixie tube for count indication.

[View Detail]

RFT Z562S
 RFT Z562S

The RFT Z562S is a neon-filled double pulse selector, similar to the Sylvania 8353 but with a maximum 5KHz counting speed.

RFT Z562S Datasheet (PDF)

[View Detail]

Raytheon CK7978 & CK8262
 Raytheon CK7978 & CK8262

Devices included in this entry:

Raytheon CK7978 selector (13-pin compact base)
Raytheon CK8262 selector (13-pin compact base; pictured in thumbnail)


The Raytheon CK7978 and CK8262 are examples of Raytheon's in-house dekatron development. While other Raytheon dekatrons are second-source versions of Sylvania devices, the CK7978 and CK8262 are original Raytheon designs. The CK7978, similar to the ETL GS10H, is a standard neon-filled double pulse selector dekatron capable of 5KHz operation.

The Raytheon CK8262 is an extremely rare experimental high speed variant of the CK7978. The CK8262 appears to be filled with some sort of Penning mixture, and can attain speeds of 100KHz.

Raytheon CK7978 Datasheet (PDF)

[View Detail]

Rodan DK23
 Rodan DK23

The Rodan DK23 is an uncommon Japanese single pulse counter with similar specifications to the ETL GC10D. Like the GC10D, the DK23 has three guides and 40 cathode positions, and is rated at 20KHz. Unlike the GC10D, the DK23 is a reliable device, and not susceptible to outgassing. The DK23 glows with a neon-like color, but its higher counting speed suggests the fill is a Penning mixture.

Rodan DK23 Datasheet (PDF)

[View Detail]

Rodan DK24
 Rodan DK24

The Rodan DK24 is an extremely rare selector variant of the DK23 with a 14-pin local base. The DK24 has similar specifications to the DK23, with a 20KHz counting speed and a Penning fill gas.

[View Detail]

STC G10/241E
 STC G10/241E

The STC G10/241E is a unique nomotron-style unidirectional counter. The G10/241E employs multi-alloy guide cathodes with different maintaining voltages in various regions of each cathode. This unusual construction requires each cathode to be connected to a resistor-capacitor network. The metal shield surrounding the cathodes obscures most of the indicating glow, rendering the G10/241E practically incapable of direct-view applications.

STC G10/241E Datasheet (PDF)

[View Detail]

Sylvania 6476A
 Sylvania 6476A

The Sylvania 6476A is an early USA-made neon filled selector dekatron. This tube is double guide, with a 4kHz counting speed and a B12E (duodecal) base.

Sylvania Decade Counter Tubes (PDF)

[View Detail]

Sylvania 6802 & 6909
 Sylvania 6802 & 6909

Devices included in this entry:

Sylvania 6802 counter (octal base; pictured in thumbnail)
Raytheon CK6802 counter (octal base)
Sylvania 6909 counter (octal base)


The Sylvania 6802 is the definitive US-manufactured dekatron, a 4KHz neon-filled double pulse counter designed to compete directly with the ETL GC10B. Sylvania also produced the 6909, a 100KHz counter that is structurally identical to the 6802, but replaces the neon fill gas with a Penning mixture. Like many high speed dekatrons, the 6909 is prone to outgassing.

Raytheon was the second-source manufacturer for the 6802 and 6909, producing a tube which was electrically identical to the Sylvania devices, but had signficant internal differences.

Sylvania Decade Counter Tubes Datasheet (PDF)

[View Detail]

Sylvania 7155
 Sylvania 7155

The Sylvania 7155 is a miniature high speed computing counter dekatron with three independent cathodes at positions eight, nine and zero. The 7155 has a Penning-type fill, and is capable of 100KHz operation. Sylvania also manufactured the 6879, a standard speed 5KHz variant with a neon fill gas.

Sylvania Decade Counter Tubes (PDF)

[View Detail]

Sylvania 8353
 Sylvania 8353

The Sylvania 8353 is a 4KHz double pulse selector in a compact envelope, similar to the Raytheon CK7978 and RFT Z562S. Sylvania also manufactured the 8035 / CT-4251, a high speed variant of the 8353.

[View Detail]

Tesla 11TU7
 Tesla 11TU7

The Tesla 11TU7 is a unique 20KHz unidirectional nomotron. The 11TU7 has a mica sheet printed with digits, suspended above a perforated shield which backlights the digits at each count position. All but the top of the envelope is painted blue, obscuring its internal construction. All specimens of this device in our collection are outgassed and non-functional.

11TU7 Datasheet (JPEG)

[View Detail]

Western Electric 6167
 Western Electric 6167

The 6167 is a highly unusual dekatron, and the only dekatron ever developed by Western Electric. The 6167 employs unique spring-shaped cathodes with extensions which are positioned over the next adjacent cathode. During operation, the glow discharge rests within the coil of the active cathode, jumping to the cathode's extension during glow transfer. This design restricts the 6167 to unidirectional operation, a fact which can be ameliorated to a certain degree by an additional zeroing cathode which immediately resets the device to zero position when pulled to ground. This feature is analogous to the 'grid zero' functionality of some beam switching tubes. Additionally, the 6167 has a supplemental anode which provides a carry function.

Western Electric 6167 Datasheet (PDF)

[View Detail]

©2000-2017 The Vintage Technology Association. All rights reserved.