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Western Electric 1B22 spark-gap tube.

1B22 size indication The tube measures 97x27mm; the larger cap is 19mm across, the smaller one 13mm.

1B22 end view

The 1B22 is an aluminium cathode spark gap tube for radar modulator use. It was developed for the ASH (later AN/APS-4) radar, where two tubes in series switched a peak power of around 105kW into a 725A magnetron. In order to maintain operation at high altitudes even if the pressurised container failed, the peak switching voltage was kept to 4kV. The tubes could pass a current pulse of 67A for 0.75µs at either 600 or 1000 pulses per second. They could also operate for short periods at 2.25µs/330pps.

Anode/cathode spacing is 150 mils, and the gas mixture at 20" pressure is 75% hydrogen and 25% argon. Life expectancy was 500 hours at 0.75µs.

Corona points at the end of the cathode opposite the end of the anode assist firing, the firing voltage being 2.7kV. The tube also contains a small quantity of radium in this region.

See also 1B29.


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