Description
Philco Aeronutronic MD-640/V Infrared Modulator for MGM-51 Shillelagh
Item Overview
This Philco Aeronutronic MD-640/V infrared modulator was part of the vehicle-mounted guidance equipment used with the MGM-51 Shillelagh guided-missile system. It converted missile-correction signals into the high-current electrical output needed to operate the system’s infrared transmitter. The transmitter then sent steering commands to the missile through a narrow infrared beam. This is original military guidance equipment and was not a component carried inside the missile.
Identification and Features
The identification of this component is confirmed by its military nomenclature, model, part number, federal stock number, and manufacturer information. Army parts documentation lists and illustrates this exact model as the “Infrared Modulator MD-640/V (10121100).”
- Official name: Modulator, Infrared
- Model: MD-640/V
- Part number: 10121100
- Original Federal Stock Number: 1430-925-2627
- Later National Stock Number: 1430-00-925-2627
- Manufacturer: Philco Corporation, Aeronutronic Division
- Contract: DAAH01-69-C-0489
- Documented vehicle applications: M551 Sheridan and M60A2
- Associated missile: MGM-51 Shillelagh
- Equipment location: Vehicle-mounted missile-guidance system
Original Service Function
The MD-640/V formed an important link between the Shillelagh system’s signal-data converter and infrared transmitter. The signal-data converter calculated the steering corrections needed to keep the missile on the gunner’s line of sight. It sent those correction commands to the modulator, which changed them into the high-current output required by the transmitter. The transmitter converted that electrical output into coded infrared signals and projected them toward the missile.
Place in the Shillelagh Guidance System
The complete guidance system included an optical tracker, rate sensor, signal-data converter, MD-640/V modulator, power supply, test checkout panel, and infrared transmitter. During flight, the tracker followed the missile and measured its movement away from the intended line of sight. The rate sensor supplied information about turret and gun movement. The signal-data converter combined this information, calculated a correction, and passed the command through the modulator to the transmitter. The gunner continued to hold the sight on the target while the vehicle equipment guided the missile.
Documented Military Applications
Army parts manual TM 9-1400-465-24P documents this exact NSN and part number for the Shillelagh installations used with both the M551 Sheridan and M60A2. The M551 technical manual also shows the modulator installed inside the Sheridan turret. Figure 10-19 covers removal and installation of the modulator and signal-data converter, while Figure 2-30 identifies the modulator among the major missile-subsystem components.
MGM-51 Shillelagh History
The MGM-51 Shillelagh was developed during the Cold War as a gun-launched guided missile for use against armored targets. It was fired through a 152mm gun-launcher instead of a separate missile rail. After launch, vehicle-mounted equipment tracked the missile and sent guidance commands through an infrared beam. This allowed the gunner to guide the missile while keeping the sight centered on the target. The same gun-launchers could also fire conventional 152mm ammunition for closer targets and other battlefield missions.
M551 Sheridan History and Use
The lightweight M551 Sheridan entered U.S. Army service during the late 1960s with the M81 152mm gun-launcher. Sheridans saw combat in Vietnam, where they were used mainly with conventional 152mm ammunition. The vehicle later served in Operation Just Cause, Operation Desert Shield, and Operation Desert Storm. Sheridan crews fired Shillelagh missiles during the 1991 Gulf War, giving the system its best-known combat use. The M551 remained in Army service for training and specialized airborne duties after many other Shillelagh-equipped vehicles had been retired.
M60A2 History and Use
The M60A2 combined an M60-series chassis with a specialized turret carrying the M162 152mm gun-launcher and Shillelagh guidance equipment. It was fielded during the 1970s and served mainly with U.S. Army units in Europe. The vehicle represented an effort to give armored units both conventional large-caliber firepower and guided anti-tank capability. Its complex electronic and missile systems required specialized testing, maintenance, and replacement components such as the MD-640/V modulator.
Manufacturer and Contract History
Philco’s Aeronutronic Division produced advanced electronic equipment for American missile, aircraft, and armored-vehicle programs during the Cold War. This modulator is associated with contract DAAH01-69-C-0489, which reflects Army procurement from the Shillelagh system’s active production period. The contract number supports a late-1960s procurement history, but it should not be treated as the exact manufacturing date of this individual component.
1978 Modification Marking
The “26 MAY 1978” date and accompanying MWO marking appear to document later modification, inspection, or depot-level work. MWO normally refers to a Modification Work Order used to update military equipment after its original production. The marking should not be described as the original manufacturing date. Without the related work-order record, the exact modification performed on this unit cannot be confirmed.
Condition
This is a used military-surplus electronic component intended for collecting, study, restoration, or display. It may show scratches, worn paint, discoloration, oxidation, connector wear, marking wear, dents, dust, missing fasteners, or other evidence of service and storage. Its electrical operation and internal completeness have not been verified, and it should not be energized without inspection by qualified personnel. A missile, signal-data converter, transmitter, tracker, power supply, cables, mounting hardware, vehicle, and other guidance components are not included unless specifically stated. Please check the pictures for the general condition of the item.
Ideal For
This original Cold War guidance component is well suited for collections and exhibits covering guided missiles, armored vehicles, military electronics, and American fire-control development.
- MGM-51 Shillelagh displays
- M551 Sheridan collections
- M60A2 vehicle exhibits
- Cold War missile collections
- Military guidance-electronics displays
- Philco Aeronutronic equipment collections
- U.S. Army fire-control exhibits
- Military museums and educational displays
Approx length 20", Approx width 13", Approx height 8", Approx weight 44lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
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