AMPTEC Research · Failsafe Igniter Testers
620EH
Mid-range explosive device igniter tester with an 8 mA failsafe current limit
The AMPTEC 620EH is a mid-range failsafe igniter tester for bridge wires, squibs, flares and other explosive devices, listed under NSN 6625-01-551-3432. Its measurement is derived from the 620A-4 meter approved by the USAF Non-Nuclear Munitions Safety Board, and a failsafe current-limiting resistor network keeps the test current under 8 mA on every range. For labs and ordnance sites that must measure resistance on igniters and explosives safely, it is the standard choice that pairs accuracy with intrinsic safety. Evencat is the sole distributor for AMPTEC Research in Taiwan.
Overview
The 620EH sits in the 620 series, the industry-standard igniter tester family, as the mid-range model for bridge wires, pyrotechnics, flares and explosive devices of every kind (NSN 6625-01-551-3432). At its core is a failsafe current-limiting resistor network that holds the maximum test current under 8 mA and clamps the open-circuit voltage at 1.6 VDC, with input protection up to 250 VDC, so a fault in the meter cannot trigger the igniter under test. Four ranges cover 2Ω, 20Ω, 200Ω and 2MΩ. Four-wire Kelvin terminals remove lead resistance from the reading, accuracy is ±0.02% of reading, and results appear on a 4 1/2 digit LED display updated 3 times per second. Power comes from four rechargeable 5AH NICAD batteries. The unit is UL-913 compliant and built under ISO 9001:2015, and is used across ordnance, aerospace and defense explosive test sites. Before ordering, pick the Kelvin lead or probe set that fits your terminals and consider Option 247 if the meter will live at a fixed station.
Key specifications
| NSN | 6625-01-551-3432 |
|---|---|
| Resistance ranges | 2Ω / 20Ω / 200Ω / 2MΩ |
| Reading accuracy | ±0.02% (2Ω to 200Ω ranges) |
| 2Ω range | 5 mA nominal, resolution ±100 µΩ, ±0.05% of range |
| 20Ω range | 5 mA nominal, resolution ±1 mΩ |
| 200Ω range | 0.5 mA nominal, resolution ±10 mΩ |
| 2MΩ range | 50 nA nominal, resolution ±100Ω, ±1% of reading |
| Maximum failsafe current | 8 mA (all ranges) |
| Open-circuit voltage | 1.6 VDC |
| Maximum input voltage protection | 250 VDC |
| Terminals / display | 4-wire Kelvin terminals; 4 1/2 digit LED display |
| Operating temperature / update rate | 0–50°C; temperature coefficient ±0.002% / 15°C; 3 readings per second |
| Power | 4 rechargeable 5AH NICAD batteries |
| Dimensions / weight | 9″ × 10″ × 3″; 8 lbs |
| Certifications | UL-913 compliant, ISO 9001:2015 |
Features
8 mA failsafe current limit
The failsafe current-limiting resistor network keeps the test current under 8 mA on every range and clamps the open-circuit voltage at 1.6 VDC, so the explosive device under test cannot be triggered.
Four mid-range spans
2Ω, 20Ω, 200Ω and 2MΩ ranges cover the mid-range resistance checks needed on bridge wires, squibs and flares.
±0.02% accuracy
±0.02% of reading on the 2Ω to 200Ω ranges with resolution down to ±100 µΩ, giving consistent and repeatable results.
4-wire Kelvin measurement
Four-wire Kelvin terminals remove lead and contact resistance from the reading, so low-resistance values stay accurate.
250 VDC input protection
Input protection up to 250 VDC adds a safety margin against miswiring or transients in the field.
Rechargeable battery power
Four rechargeable 5AH NICAD batteries, a 4 1/2 digit LED display and 3 updates per second make it a practical carry-along meter.
Typical applications
Munitions QC
Outgoing bridge-wire resistance acceptance on military munitions
At munitions manufacturing and assembly plants, QC engineers use the 620EH to measure every bridge-wire initiator before shipment and confirm its resistance falls within design tolerance. The failsafe circuit caps the test current under 8mA, so stray current cannot fire the explosive during the check, in line with USAF Non-Nuclear Munitions Safety Board requirements.
Aerospace integration
Ignition circuit continuity checks on rocket and satellite launch systems
During integration of rocket motor igniters, satellite explosive bolts and ejection seat cartridges, aerospace contractors use the 4-wire Kelvin terminals of the 620EH to confirm resistance at ±0.02% accuracy, free of contact resistance. NASA and the USAF have long used this class of meter as the final acceptance tool for ignition circuits.
Pyrotechnic and fuze testing
Field continuity checks on military pyrotechnic and flare igniters
Logistics and ground crews running pre-firing safety checks on flares, signal cartridges and explosive bolts rely on the internal rechargeable NiCAD batteries of the 620EH to work outdoors from 0°C to 50°C without external power. The 4 1/2 digit LED display updates 3 times per second, so operators confirm each fuze quickly and avoid duds and accidental ignition.
Options and configuration
Tick the options you need. We compile the configuration into a list and carry it into the quote form.
Standard equipment (included)
Hardware / instrument options
Test lead and probe options
Downloads
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Also available for rent: 620EH is part of the AMPTEC rental program, for project peaks, calibration backup and pre-purchase trials. Rental inquiry →