1B49 Series Spark Gap

The 1B49 is a gas-filled series spark gap containing two electrodes. It is designed to operate within a frequency range of 120 to 2000 Cycles/Sec.

Physical Construction and Mounting Requirements

The 1B49 is a two-electrode device utilizing gas as its ionizable medium.

The physical dimensions of the 1B49 are:

• Overall Height: 5" ± 1/8"
• Maximum Body Diameter: 2-3/8"
• Cathode Terminal (Top): Diameter of 1.238" (+0.025" / -0.015") and a length of 21/32" ± 1/32"
• Anode Terminal (Bottom): Diameter of 0.566" ± 0.015" and a length of 9/16" ± 1/32"

For proper installation, the mounting position of the 1B49 must be with the Cathode End Up and within 60° of vertical.

Electrical Characteristics

The electrical characteristics of the 1B49 are defined by the following parameters:

• Frequency Range: 120 to 2000 Cycles/Sec
• Instantaneous Breakdown Voltage (Initial Peak): 12.0 Kilovolts
• Instantaneous Breakdown Voltage (Recurrent Peak): 11.5 Kilovolts
• Voltage Drop: 100 Volts, measured after 0.5 Microseconds
• Interelectrode Capacitance: 7 Micro Microfarads

Maximum Ratings and Operating Limits

The maximum ratings for the 1B49 are:

• Peak Power Dissipation: 45 Kilowatts
• Peak Current: 450 Amperes
• Average Power Dissipation: 25 Watts
• Average Current: 210 Milliamps
• Frequency: 2000 Cycles/Sec
• Ambient Temperature Range: -50 to +100°C
• Duty Cycle: 0.001

Calculated Operating Relationships

The relationship between the peak and average ratings can be analyzed mathematically using the specified maximum duty cycle of 0.001:

• Power Dissipation Calculation: Operating at the maximum peak power dissipation of 45 Kilowatts with a duty cycle of 0.001 yields a calculated average power dissipation of: $45,000 \text{ W} \times 0.001 = 45 \text{ Watts}$ Because the maximum average power dissipation rating is restricted to 25 Watts, the average power dissipation limit is the overriding constraint.

• Current Calculation: Operating at the maximum peak current of 450 Amperes with a duty cycle of 0.001 yields a calculated average current of: $450 \text{ A} \times 0.001 = 0.450 \text{ Amperes} \text{ (450 Milliamps)}$ Because the maximum average current rating is restricted to 210 Milliamps, the operating parameters must be adjusted to avoid exceeding this limit.

Technical Summary

The 1B49 is a gas-filled series spark gap featuring a two-electrode configuration. It operates within a frequency range of 120 to 2000 Cycles/Sec, with an initial peak breakdown voltage of 12.0 Kilovolts and a recurrent peak breakdown voltage of 11.5 Kilovolts. The device exhibits a voltage drop of 100 Volts measured after 0.5 Microseconds and has an interelectrode capacitance of 7 Micro Microfarads.

Mechanically, the 1B49 must be mounted with the cathode end up and within 60° of vertical. Its physical dimensions include an overall height of 5" ± 1/8", a maximum body diameter of 2-3/8", a top cathode terminal, and a bottom anode terminal. The device is rated for a maximum peak power dissipation of 45 Kilowatts, a peak current of 450 Amperes, an average power dissipation of 25 Watts, an average current of 210 Milliamps, and a maximum duty cycle of 0.001, within an ambient temperature range of -50 to +100°C.