AMPTEC Research · Failsafe Igniter Testers
620MG
Wide-range failsafe digital ohmmeter for ultra-safe testing of initiator bridge wires and explosive devices
The Amptec 620MG is a failsafe digital ohmmeter for ultra-safe resistance testing on squibs, flares, bridge wires and other explosive devices (NSN # 6625-01-667-0237). It descends from the 620A-4 approved by the USAF Non-Nuclear Munitions Safety Board and adds autorange, a diode test and a failsafe current limit of 8 mA. Lab and arsenal engineers choose it because it measures to ±0.02% while guaranteeing the initiator cannot be fired during the test. Evencat is the sole distributor for AMPTEC Research in Taiwan.
Overview
The 620MG failsafe ohmmeter is built for ultra-safe resistance testing on squibs, flares, bridge wires and other explosive devices (NSN # 6625-01-667-0237). It descends from the 620A-4, the meter approved by the USAF Non-Nuclear Munitions Safety Board that set the pattern for the igniter tester product line. Seven ranges run from 2 Ω to 2 MΩ with a base accuracy of ±0.02%, and the 4-wire Kelvin configuration removes lead resistance error. The failsafe circuit caps the current at 8 mA under any fault, and the diode test lets you measure initiators that contain a protective diode without special fixtures. The RS232C interface (OP-232) and optically isolated power (OP-247) are standard, and the meter complies with ISO 9001:2015 and UL-913. That makes it the natural choice for ordnance, aerospace and defense labs that want a bench meter with autorange and a data port rather than a battery-powered field unit. Before ordering, decide whether you need the isolated analog output or the rack mount kit for a fixed station.
Key specifications
| Ranges | 2 Ω / 20 Ω / 200 Ω / 2000 Ω / 20K Ω / 200K Ω / 2M Ω (7 ranges) |
|---|---|
| Base accuracy | ± .02% of reading & range |
| Failsafe current | 8 mA (all ranges) |
| Nominal test current | 5 mA (2 Ω / 20 Ω) down to 0.5 µA (200K Ω / 2M Ω) |
| Best resolution | 0.1 mΩ (2 Ω range) |
| Display | 4 1/2 digit LED |
| Terminal configuration | 4-wire Kelvin |
| Temperature coefficient | ± .002% per 1°C |
| Update rate | 3/sec |
| Maximum input voltage | 250 VDC |
| Open-circuit voltage | 1.6 VDC |
| Operating temperature | 0° to 50°C |
Features
Failsafe current limit
The failsafe circuit caps the test current at 8 mA under any fault, so squibs and bridge wires cannot be fired by the measurement.
Diode test
A built-in diode test lets you measure initiators that contain a protective diode without extra equipment.
Wide range, high accuracy
Seven ranges from 2 Ω to 2 MΩ with autorange and a base accuracy of ±0.02% of reading & range.
4-wire Kelvin measurement
The 4-wire Kelvin terminal configuration removes lead and contact resistance error, with resolution down to 0.1 mΩ.
RS232C and isolated power as standard
The RS232C interface (OP-232) comes standard for data capture, and optically isolated power (OP-247) keeps the meter isolated from the mains.
Industry safety standards
Complies with ISO 9001:2015 and UL-913, and descends from the 620A-4 approved by the USAF Non-Nuclear Munitions Safety Board.
Typical applications
Aerospace launch
Acceptance testing of rocket and spacecraft igniters
In launch preparation, NASA and aerospace contractors use the 620MG to measure motor igniters (squibs) and bridge wire components, confirming the value sits inside specification and the circuit is complete. The diode test verifies polarity and conduction of protective elements, and the 8mA failsafe limit keeps the whole check free of any risk of accidental firing.
Military munitions
Safety ohmmeter testing on non-nuclear munitions (USAF approved practice)
Under practice approved by the USAF Non-Nuclear Munitions Safety Board, which set the 620A-4 predecessor of the 620MG as the reference meter, ordnance technicians measure bridge wire resistance through the 4-wire Kelvin terminals during repair and intake of bombs, flares and missile initiators, confirming values to ±0.02% accuracy. NSN 6625-01-667-0237 lets logistics order the meter directly.
Ground test station
Combined diode and resistance verification in an EOD laboratory
Explosive ordnance disposal and QC laboratories need both the bridge wire resistance of an initiator and the health of its built-in protective diode. The 620MG combines a diode test with the ohmmeter, so technicians finish both measurements without changing instruments, and its optically isolated power keeps the meter fully isolated from ground, in line with UL-913 intrinsic safety for use around explosive gases.
Options and configuration
Tick the options you need. We compile the configuration into a list and carry it into the quote form.
Standard package (included)
Hardware options
Downloads
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