MX-11769
MX-11769 is a specification for image intensifier tubes for the U.S. military.
The designation is often used to refer to the format of the tube specified inside of the specification, as all iterations of the specification reuse the same format to facilitate backwards compatibility.
The format is a modified version of the MX-10160 format, with the key difference being the so called pigtail, which can be plugged into compatible housings to allow manual gain adjustment.
MX-10160 tubes can be used in housings designed for the MX-11769 format, simply rendering the gain adjustment inoperable. See Conversion for the inverse case.
Pigtail
The pigtail is a two-lead ribbon cable soldered to two pin contacts inside of a small cutout on the image intensifier housing.
At the other end of the cable is a small circuit board featuring four pin contacts, forming a type of connector that can be plugged into a receptacle in the inside of a compatible night vision housing. As there are only two leads, the pins form two pairs for redundancy. Furthermore, the assymetric arrangement of the pins ensures that there is only one possible direction that the connector can be plugged in.[1][Note 1]
The electronic principle is simple, as the gain of the image intensifier can be controlled by adjusting the resistance between the two contacts. This is usually achieved by a simple potentiometer control (e.g. in the AN/PVS-14), or by some digital controller and buttons to control the gain.
The tube will run at maximum gain at 180KΩ, and at minimum gain at 0Ω.
Conversion
On newer tubes from L3Harris the ribbon cable is connected to the image intensifier using a plug instead of soldered pins. These tubes feature extra circuitry making the tube operate at full gain when the cable is disconnected, allowing for quick conversion to and from MX-10160 format without the use of any tools.
Some newer tubes sold by Elbit as MX-10160 use the same principle, allowing a pigtail to be connected later, converting them to MX-11769 format.
Manual Conversion
Furthermore, its possible to convert any MX-11769 tubes to MX-10160 format by desoldering the ribbon cable and replacing it with a resistor. The recommended type of resistor is a 0805 SMD resistor, with a value of 150-180KΩ depending on the desired gain.
A normal MX-11769 tube running without a resistor or with a resistor exceeding the 180KΩ mark will operate beyond maximum gain, likely shortening the lifespan of the image intensifier significantly.
Due to the small size of the resistor and the pins the conversion requires some experience, otherwise risking damage to the image intensifier.
Devices
The table below lists all devices using MX-11769 image intensifier tubes for which a page exists on this wiki.
| Manufacturer | Housing Type | |
|---|---|---|
| AN/PVS-14 | L3Harris Elbit Systems Of America Carson Industries Inc. | Monocular |
| Simrad GN-1 | Simrad | Bi-ocular |
Notes
- ↑ Even if it were possible, a connector plugged in reverse would not have any effect on the functionality. The single direction that it can be plugged in is intended to avoid confusion and to ensure a single standard of assembly.
References
- ↑ Patent by ITT: Variable gain image intensifier
