The Vintage Technology Association - Spark Gap Tubes, Trigger Tubes & Passives

Spark Gap Tubes, Trigger Tubes & Passives

This section is a catch-all for simple vacuum and gas-filled devices used in relay and passive applications.

Bomac JAN-CBNQ-724B

Devices included in this entry:

Bomac JAN-CBNQ-724B TR cell
Sylvania 724B (pictured in thumbnail)

The 724B is a TR cell, a device used to protect the receiver portion of a microwave transceiver which shares the same antenna for both transmit and receive functions. A TR cell functions like a triggered gap tube, and blocks the receiver hardware by shorting the receiver input during transmitter operation. Transmitter pulses cause the spark gap to break down, shorting the receiver input.

The 724B was used in several WWII-era 10GHz mobile radar systems, including the AN/APS-1, ASD (AN/APS-3) ASH (AN/APS-4) and AN/MPG-1.

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Bomac BL-693
	The Bomac BL-693 is a TR cell doped with the beta emitter Co-60. The initial radioactivity at the time of manufacture was rated at 11.1 kBq, but at the time of this writing has decayed to approximately 10 Bq. The initial Co-60 content of the BL-693 was 0.00000000025g, most of which has now been converted into stable Ni-60. [View Detail]

Bomac BL11 / 6282
	The Bomac BL11 / 6282 is a small cobalt-doped K-band TR cell with an operating frequency range of 23.6 to 24.6GHz. [View Detail]

Central Electric CVS-1

The Central Electric CVS-1 is a high voltage vacuum switch constructed into a large T-shaped envelope. This tube has three contacts; a fixed contact imbedded in glass, and two movable contacts that pass through sheet metal plates. The plates are flexible, allowing the movable contacts to opened and closed by an external force without breaking the vacuum. The tube's getter is located in one leg of the tube, attached to the base of the fixed contact.

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GA4 (Unknown Mfr.)
	The GA4 is a large spark gap tube of unknown specification. The two electrodes on either side of the envelope are designed to be removed, and are held in place by a pair of Allen screws. This tube illuminates purple when subjected to an electrostatic field, which suggests it is filled with either hydrogen or water vapor, depending on it's original purpose. [View Detail]

C.P. Clare XG-1288
	The C.P. Clare XG-1288 is an unusual, large cermet spark gap tube of unknown specification. [View Detail]

Eimac CIM-481274
	The Eimac CIM-481274 is a typical vacuum capacitor of unknown specification, though it appears to be extremely similar to the Eimac VC50-32, a 32kV, 50pF device. Portions of the CIM-481274's envelope are doped with uranium. [View Detail]

G.L.A. 20750
	The 20750 is spark gap tube designed to be used as a load in high frequency applications. We can find no information on this device, but it was most likely used as an overvoltage protection system in some high power transmitter.

General Electric GL-6452
	The General Electric GL-6452 is a microwave reference cavity, probably the simplest type of vacuum device in existence. Reference cavities are little more than a vacuum enclosed in a metal box with two glass apertures, and perform the function of stabilizing the output frequency of magnetrons and other microwave sources. The GL-6452 operates in the X-band range, 9.35GHz. [View Detail]

General Electric Co. VI507
	The General Electric Co. (GEC) VI507 is an argon-mercury spark gap tube used as a TR cell in Great Britain's second-generation AMES Type 2 metric radar network. The VI507 is rated for several hundred hours of operation at 25kW. A note of disambiguation, GEC should not be confused with the US company General Electric (GE). [View Detail]

Sperti 473384-2
	This device, which functions as a high frequency relay, consists of a spark gap bridged by a pivoting metal contact mounted on a glass bead. The entire mechanism is sealed in a complex T-shaped vacuum envelope. The underside of the tube is sealed with a rubbery material, allowing the contacts to be mechanically opened and closed by pressing the terminal exiting the bottom of the tube.

Sylvania 0A5

The 0A5 is a gas filled trigger tube designed as a high speed replacement for clunky mechanical relays. The 0A5 is a descendant of "Strobotron" neon filled flash tubes like the 1D21, but has an anode structure specifically designed for fast switching. In fact, one of the recommended uses of the 0A5 is as a trigger for gas filled flash tubes like the Strobotron. Sylvania departed from their normal print manufacturing techniques for this tube and put a lacquer coating over the logo and part number, similar to the coating used on some Russian tubes, to protect it from damage.

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Sylvania 6068A

The 6068A is a relatively undocumented TR cell with a complex internal construction. The cavity of this tube appears to be wholly separate from the actual waveguide interface, which is the large copper block in the center of the tube. The center of the copper block contains a tunable spark gap, which can be adjusted by turning a screw in the large steel cylinder at the base of the tube. Note that this tube has two separate sealing pips, and possibly contains separate cavities.

[View Detail]

Sylvania 5823
	The 5823 is a 7-pin argon-filled trigger tube. This tube is triggered by a 70 volt signal, and can switch a load of up to 200 volts. The 5823 is a cold cathode device; unlike some gas filled switching tubes, no filament voltage is required. [View Detail]

Sylvania BW382
	We don't know much about this TR cell, but it is almost surely one of the smallest of such devices ever put into production. Little more than a glass window, the BW382 is quite small; dimensions are 24mm by 12mm and the device is a mere 1mm thick. [View Detail]

WE / GE 8047
	The Western Electric (manufactured by GE) 8047 is a small, fairly typical vacuum capacitor. The device is rated at 50 pF, 5kV@5A. [View Detail]