Description
U.S. Army Multimeter M17 for the 762mm MGR-1 Honest John Rocket System
Item Overview
The U.S. Army Multimeter M17 is a dedicated electrical test set for the 762mm MGR-1 Honest John artillery rocket system. Unlike a general-purpose multimeter, it was configured specifically to inspect the rocket motor’s ignition and spin-rocket circuits before assembly and firing. Army instructions required this tester because its low-voltage ohmmeter circuit could check sensitive igniter wiring without applying enough electrical energy to fire a squib. The M17 itself is non-explosive support equipment.
Identification and Features
The tester’s case markings identify applications for the M31-series MGR-1A and the improved XM50/M50 MGR-1B Honest John rockets. The worn identification plate appears consistent with FSN 1055-620-6501. System-specific switches, receptacles, test leads, and adapters allowed one instrument to check several parts of the rocket-motor electrical system. Accessories numbered 8430052 and 8430057 match the igniter-test extension and motor-igniter adapter listed for the M17 equipment set.
- Official designation: Multimeter M17
- Probable FSN: 1055-620-6501
- Weapon system: 762mm MGR-1 Honest John
- Rocket applications: M31-series MGR-1A and XM50/M50 MGR-1B
- Ohmmeter operating voltage: 1.5 volts
- Igniter-test extension: P/N 8430052
- Motor-igniter adapter: P/N 8430057
- Main-motor igniter circuit testing
- Spin-motor and spin-rocket squib circuit testing
- Spin-motor switch testing
- Continuity and insulation-to-ground testing
Historical Background
The M17 was developed as specialized support equipment for the Honest John rocket program during the Cold War. Its dedicated panel and adapters were needed because an ordinary electrical tester could apply excessive test current to a sensitive igniter circuit. Army procedures therefore identified the M17 as the authorized tester for the rocket-motor electrical system. A 1962 Army modification work order addressed the M17 panel assembly, showing that the tester remained under formal maintenance and improvement after its introduction.
Function and Testing Capabilities
The M17 checked the electrical paths needed to ignite the Honest John’s main rocket motor and spin system. Its test functions covered the main-motor and spin-motor igniter circuits, eight spin-rocket squib circuits, the spin-motor switch, general wiring continuity, and insulation resistance between the wiring and ground. The operator connected the proper adapter or extension, selected the required circuit, and read the meter for the prescribed indication. These checks located open circuits, shorts, grounded wiring, and other faults that could prevent correct rocket operation.
Safety-Controlled Test Design
Rocket igniters and squibs can function when sufficient electrical current reaches them. The M17 reduced that risk by using a 1.5-volt ohmmeter circuit designed for the Honest John ignition system. This low-energy arrangement allowed crews to check resistance and continuity while limiting the chance of an accidental ignition caused by the tester. Using the correct test set was an important part of the Army’s assembly, inspection, and prelaunch safety procedure.
Documented Rocket Applications
The case markings and Army maintenance documentation connect the M17 with both main Honest John variants. The M31 series was later designated MGR-1A. Its improved successor began as the XM50, entered service as the M50, and was later designated MGR-1B. Although the two rocket versions differed in size, performance, and motor construction, both required inspection of their ignition and spin-system electrical circuits. The M17 and its issued adapters allowed the appropriate checks to be made for the supported rocket configuration.
Honest John Weapon-System Background
The MGR-1 Honest John was a mobile, unguided surface-to-surface artillery rocket developed at Redstone Arsenal during the early 1950s. The M31 version was fielded in 1954 and became the U.S. Army’s first nuclear-capable surface-to-surface rocket. Honest John could carry nuclear or conventional warheads and extended field-artillery firepower far beyond the range of conventional guns. The improved M50/MGR-1B was smaller, lighter, faster, and longer-ranged than the original M31 system. Honest John remained an important Army field-artillery weapon until it was replaced by the MGM-52 Lance during the 1970s.
Rocket Electrical-System Background
Honest John was an unguided rocket, but its motor section still depended on a carefully arranged electrical ignition system. The main igniter started the large solid-propellant motor. Separate spin rockets or spin motors produced stabilizing rotation as the rocket began moving from the launcher, reducing errors caused by uneven thrust. Electrical switches, squibs, cables, receptacles, and igniter components had to function in the correct sequence. The M17 allowed crews to confirm those circuits before the rocket was placed in firing condition.
History of Use
Honest John batteries served with the U.S. Army and allied forces throughout much of the Cold War. Rocket components were transported separately and assembled near the firing position, where trained crews conducted inspections before placing the round on its launcher. The M17 was used during this preparation and maintenance process to verify the motor and spin-system wiring. Its low-voltage design allowed technicians to perform required electrical checks while protecting the sensitive firing components from unintended current.
Condition
The tester appears substantially intact and retains its fitted carrying case, operating panel, wiring, and several associated accessories. Components marked 8430052 and 8430057 correspond to the original igniter-test extension and motor-igniter adapter. A complete inventory of every lead, adapter, probe, and small accessory would be required before describing the set as complete. The case, panel, hardware, and markings show age and storage wear.
Ideal For
The M17 is a strong display and research piece for collections focused on Honest John, Cold War field artillery, nuclear-capable Army weapons, military electrical test equipment, or rocket-support tools. Its specialized controls and adapters help explain the inspection work required before an Honest John rocket could be prepared for firing.
- MGR-1 Honest John collections
- Cold War field-artillery displays
- Army rocket and missile exhibits
- Military electrical-test-equipment collections
- Nuclear-artillery history displays
- Technical research and restoration reference
Approx length 15", Approx width 10", Approx height 10", Approx weight 17.9lbs.
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