Spark Gap Tubes, Trigger Tubes & Passives

This exhibit includes simple vacuum and gas-filled devices used in relay and passive applications, including spark gap tubes, TR cells, reference cavities and vacuum capacitors.

Bomac JAN-CBNQ-724B
 Bomac JAN-CBNQ-724B

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
 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.

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Bomac BL11 / 6282
 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.

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Bomac BLA-009
 Bomac BLA-009

The Bomac BLA-009 is a TR cell of unknown specification, doped with Co-60.

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Bomac USN-CBNQ-6024
 Bomac USN-CBNQ-6024

Introduced by Sylvania in 1952, the 6024 is a large gas-filled ATR cell which operates in the upper UHF band, between 2.65MHz and 2.95MHz. The 6024 is intended for radar applications, and is rated for a maximum transmitter power of 1MW. Like many TR and ATR cells, the 6024 is doped with Co-60.
The example pictured here is a USN-CBNQ-6024, manufactured by Bomac.

Sylvania 6024 Datasheet (PDF)

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C.P. Clare XG-1288
 C.P. Clare XG-1288

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

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Eimac CIM-481274
 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.

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GLA 20750
 GLA 20750

The GLA 20750 is spark gap tube of unknown specification. It was likely used in an overvoltage protection system in a high power transmitter.

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General Electric GL-6452
 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.

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General Electric Co. VI507
 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.

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Sylvania 721B
 Sylvania 721B

Introduced in the early 1940s, the Sylvania 721B is a large external cavity disc-seal TR cell with an operating frequency range of 2.7-3.3GHz. The 721B is a long-life variant, while the 721A is a standard variant of the same device.

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Western Electric 8047
 Western Electric 8047

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

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