7665A Hydrogen-Filled Ceramic Thyratron The data to be read in conjunction with the Hydrogen Thyratron Preamble. DESCRIPTION The 7665A is a rugged hydrogen thyratron designed for use in compact military and civil radars. It has a ceramic envelope with a mounting flange and flying lead connections. It features low jitter and low anode delay time and is suitable for use at high pulse repetition rates; it can switch peak powers up to 3 MW. The tube will operate over an ambient temperature range of 755 to +130 8C. A hydrogen reservoir is incorporated. This tube was designed to comply with, and is electrically tested to, MIL-E-1/1485D. Peak forward anode voltage . . . . . . 16 kV max Peak inverse anode voltage . . . . . . 16 kV max Peak anode current . . . . . . . . 350 A max Average anode current . . . . . . . 500 mA max Rate of rise of anode current . . . . 2000 A/ms max Anode heating factor . . . . . . . 5 x 109 VApps max GENERAL Electrical Cathode (connected internally to one end of heater) . . Heater voltage . . . . . Heater current . . . . . Reservoir voltage . . . . Reservoir current . . . . Tube heating time (minimum) . . . . . . . . . . . . . . . . . . . . . . . . . . oxide coated . 6.3 + 7.5% V . 4.5 A . 6.3 + 7.5% V . 2.0 A . 3.0 min Mechanical Seated height . . . . Clearance required below mounting flange . . . Overall diameter (mounting flange) . . Net weight . . . . . Mounting position . . . Base . . . . . . . . . 63.5 mm (2.500 inches) max PULSE MODULATOR SERVICE MAXIMUM AND MINIMUM RATINGS . . . 25.4 mm (1.000 inch) min (Absolute values) . 57.15 mm (2.250 inches) max . . 160 g (0.35 pound) approx . . . . . . . . . . any . . . . . . flange mounting Anode Min Cooling . . . . . . . . . . . natural or forced-air When operating at maximum anode dissipation, forced-air cooling up to 0.14 m3/min (5 ft3/min) should be directed into the anode cup. Peak forward anode voltage (see note 1) . . . . . . . . Peak inverse anode voltage (see note 2) Peak anode current . . . . . . Average anode current . . . . . Rate of rise of anode current (see note 3) . . . . . . . . Anode heating factor . . . . . . . . . . – – – – . – . – Max 16 16 350 500 kV kV A mA 2000 A/ms 5 x 109 VApps e2v technologies (uk) limited, Waterhouse Lane, Chelmsford, Essex CM1 2QU, UK Telephone: +44 (0)1245 493493 Facsimile: +44 (0)1245 492492 e-mail: [email protected] Internet: www.e2v.com Holding Company: e2v technologies plc e2v technologies inc. 4 Westchester Plaza, PO Box 1482, Elmsford, NY10523-1482 USA Telephone: (914) 592-6050 Facsimile: (914) 592-5148 e-mail: [email protected] # e2v technologies (uk) limited 2005 A1A-7665A Issue 5, November 2005 282G/2639 MAXIMUM AND MINIMUM RATINGS (Continued) Min Max Grid Unloaded grid drive pulse voltage (see note 4) . . . . . . Grid pulse duration . . . . Rate of rise of grid pulse (see note 3) . . . . . . Peak inverse grid voltage . . Forward impedance of grid drive circuit . . . . . . . 200 . . . 2.0 600 – V ms . . 300 . . . – – 200 V/ms V . . 500 O 50 Heaters Cathode heater voltage . . . . . . Reservoir heater voltage . . . . . . Tube heating time . . . . . . . . 6.3 + 7.5% 6.3 + 7.5% 3.0 – V V min Environmental Environmental performance . . . . . . . see note 5 Ambient temperature . . . . . . 755 +130 8C Altitude . . . . . . . . . . . – 3 km – 10 000 ft CHARACTERISTICS Min Typical Max Critical DC anode voltage for conduction (see note 6) . Anode delay time (see notes 6 and 7) . . . Anode delay time drift (see notes 6 and 8) . . . Time jitter (see notes 6 and 9) Heater current (at 6.3 V) . Reservoir current (at 6.3 V) . . . – 0.4 1.0 kV . . – 0.25 0.4 ms . . . . 0.05 3.0 4.5 2.0 0.1 5.0 5.5 3.0 ms ns A A . . . . – – 3.5 1.0 NOTES 1. This is the maximum forward hold-off voltage imposed on the thyratron in a pulse modulator circuit. Tubes are tested at 18 kV peak forward anode voltage with the charging reactor inductance and pulse forming network capacitance resonant at 1000 pps For instantaneous starting applications the maximum permissible peak forward voltage is 16 kV; this must not be reached in less than 0.04 s and there must be no overshoot. 2. In pulsed operation the peak inverse anode voltage, exclusive of a spike of 0.05 ms maximum duration, must not exceed 5.0 kV during the first 25 ms after the pulse. 3. This rate of rise refers to that part of the leading edge of the pulse between 25% and 75% of the pulse amplitude. 7665A, page 2 4. Measured with respect to cathode potential. 5. The tube has been designed to withstand the following tests: (a) Vibration – Vibrated at 10 g in each of 3 planes through the range 10 to 50 Hz and back again to 10 Hz in 10 minutes whilst looking for resonances in the range 0 to 2000 Hz. (b) Long Duration Shock – Tested at 100 g for 11 ms with 3 blows in each plane. (c) High Temperature Test – Tested at an ambient temperature of 150 8C under normal operating conditions for 5 hours. 6. The typical figures are obtained on test using conditions of minimum grid drive. Improved performance can be expected by increasing the grid drive. 7. The time interval between a point on the leading edge of the unloaded grid pulse at 25% of the pulse amplitude and the point where anode conduction takes place. 8. Taken as the drift in delay time over an 8-minute run at full ratings between the second and tenth minutes of operation. 9. The variation of firing time measured at 50% of current pulse amplitude. HEALTH AND SAFETY HAZARDS e2v technologies hydrogen thyratrons are safe to handle and operate, provided that the relevant precautions stated herein are observed. e2v technologies does not accept responsibility for damage or injury resulting from the use of electronic devices it produces. Equipment manufacturers and users must ensure that adequate precautions are taken. Appropriate warning labels and notices must be provided on equipments incorporating e2v technologies devices and in operating manuals. High Voltage Equipment must be designed so that personnel cannot come into contact with high voltage circuits. All high voltage circuits and terminals must be enclosed and fail-safe interlock switches must be fitted to disconnect the primary power supply and discharge all high voltage capacitors and other stored charges before allowing access. Interlock switches must not be bypassed to allow operation with access doors open. X-Ray Radiation All high voltage devices produce X-rays during operation and may require shielding. The X-ray radiation from hydrogen thyratrons is usually reduced to a safe level by enclosing the equipment or shielding the thyratron with at least 1.6 mm ( 1/16 inch) thick steel panels. Users and equipment manufacturers must check the radiation level under their maximum operating conditions. # e2v technologies OUTLINE (All dimensions without limits are nominal) ANODE CONNECTION FITTED WITH 8-32 UNC SCREW 5027C 1B A C E MOUNTING FLANGE SEE NOTE 1 F SEE NOTE 2 D Ref Millimetres Inches A B C D E F G H J K L M 61.90 + 1.52 34.93 + 0.25 49.20 + 1.52 7.09 max 0.81 25.4 max 38.1 max 4.19 51.6 57.15 max 152.4 5.16 2.437 + 0.060 1.375 + 0.010 1.937 + 0.060 0.279 max 0.032 1.000 max 1.500 max 0.165 2.031 2.250 max 6.000 0.203 Inch dimensions have been derived from millimetres. Outline Notes 1. The mounting flange is the connection for the cathode, cathode heater return and reservoir heater return. 2. A minimum clearance of 25.4 mm (1.000 inch) must be allowed below the mounting flange. 3. Where e2v technologies gives prior agreement to the use of alternative lead/mounting arrangements on these posts, great care must be taken to avoid damaging the threads and the metal/ceramic joints. A flat wrench must be used to hold the nut nearest the ceramic while a torque wrench, set to a value of less than 0.046 kg-m (4 lb-in), is used on the other nut. SEE NOTE 3 1G RESERVOIR HEATER LEAD (RED) L LONG, TAG TO FIT 1M TERMINAL GRID LEAD (GREEN) L LONG TAG TO FIT 1M TERMINAL 1K CATHODE HEATER LEAD (YELLOW) L LONG, TAG TO FIT 1M TERMINAL 4 HOLES 1H EQUISPACED ON J PCD Whilst e2v technologies has taken care to ensure the accuracy of the information contained herein it accepts no responsibility for the consequences of any use thereof and also reserves the right to change the specification of goods without notice. e2v technologies accepts no liability beyond that set out in its standard conditions of sale in respect of infringement of third party patents arising from the use of tubes or other devices in accordance with information contained herein. # e2v technologies Printed in England 7665A, page 3