Associated model numbers: MDT, MDT-2, MDT-4

The MegaCode series of digital transmitters are wireless radio controls designed for use with automatic garage door and gate openers. The MegaCode radio format provides unparalleled security. The system can be programmed to more than a million different codes.

MegaCode transmitters and receivers do not contain a typical "coding switch" as in Linear’s standard digital receivers. Each transmitter is pre-set at the factory to a unique code. Receiving a signal from the transmitter(s) that are going to be used with it programs the receiver. This stores the transmitter’s code in the receiver’s memory. The receiver will retain its memory even without power. The receiver will activate only from these "memorized" transmitters. Please refer to the receiver’s instructions for maximum transmitter capability.

The transmitters are powered from two type 2032 lithium "button-cell" batteries. When the batteries get low, the bright red Led light on the transmitter will start to dim as the unit is activated. When the red LED no longer lights when the transmitter is activated, the batteries should be replaced.

MDT – Single-channel transmitter with a button on the front and the top (both buttons perform the same function.

MDT-2 – Three channel transmitter with two buttons on the from and one button on the top (each button performs a separate function).

MDT-4 – Five channel transmitter with four buttons on the front and one button on the top (each button performs a separate function)

*************   WARNING   *************

            Moving Door can cause serious injury or death.

·         DO NOT install transmitter unless the door operator’s safety reverse works as required by the door operator’s manual.

·         Wall control must be mounted in sight of door, at least 5 feet above floor and clear of moving door parts.

·         Keep people clear of opening while door is moving.

·         DO NOT allow children to play with the transmitter or door operator.

If safety reverse does not work properly:

·         Close door then disconnect operator using the manual release handle.

·         DO NOT use transmitter or door operator.

·         Refer to Door and Door Operators Owner’s Manuals before attempting any repairs.

            Electrical Shock can cause serious injury or death.

·         Power cord must be unplugged before attaching any wires,

·         Be sure wire ends do not touch each other or other terminals.

If you have questions or if you need a manual, contact the distributor or manufacturer of the operator.


MDR/MDRNR/MDR2 Program button and Led Location. Locate the program button and LED on the side of the receiver case.

MDRM/MDRM2 Program button and LED Location. Locate the program button and LED on the back of the receiver case.


Momentarily press the receiver’s program button (channel one or two). The red programming LED will light if there’s room in the receiver’s memory. A transmitter must be entered while the LED is on. Press the desired transmitter button. The LED will flicker indicating that the receiver has accepted the transmitter.

NOTE: Be sure to press the receiver program button for less than 2 seconds.

WARNING: Door operator will not activate when the receiver is being programmed from the transmitter, but the door operator will activate the next time the transmitter is activated after programming.

NOTE: The programming LED also monitors radio signals entering the receiver. It is common to see an occasional blink from the LED. The LED will also light when any transmitter tuned to the receiver’s frequency (programmed into the receiver or not) is activated.


Repeat the steps above for each transmitter used with the receiver. Be sure to press the receiver’s program button each time a new transmitter or a different transmitter button on a multi-button transmitter is pressed. If the LED doesn’t come on when the receiver’s program button is pressed, the receiver’s memory is full. Use the erase function to remove transmitters from the receiver’s memory. (Refer to # 6 Erasing Receiver Memory).


Press and hold the receiver’s program button (channel one or two) until the LED begins to flash or flashes. The number of flashes equals the number of transmitters programmed into the channel of the receiver.

NOTE: Don’t hold down the programming button longer than 5 seconds, the receiver’s memory for that channel will be erased.


Be sure door area is clear. Activate each transmitter. The receiver relay should click, (relay output models only) and the operator should activate. Wait 2 seconds between each activation.


Transmitters may be erased for the receiver’s memory by pressing and holding the receiver’s program button (channel one or two) for 5 seconds or more. After the Led blinks (count of transmitters) it will blink one more time for channel one and twice for channel 2 as the receiver’s memory for that channel is erased. All transmitters for each receiver channel are erased at the same time.


OPEN BATTERY COMPARTMENT. To access the transmitter’s batteries remove the battery access screw on the back of the unit. Flip the unit over so that the front is facing you. Use a small screwdriver to open the battery compartment.

REPLACING TRANSMITTER BATTERIES. Replace the two batteries with two type 2032 lithium batteries or equivalent. The batteries stack on top of each other with the (+) sides facing the front of the transmitter. Replace with new batteries then close the battery compartment, replace battery screw and test transmitter.

VISOR CLIP REMOVAL. The visor clip can be removed by removing the three screws on the back of the remote. Slide the clip off the retaining plate and reattach the plate to the transmitter.

NOTE: The same transmitter (or the same transmitter button on multi-button transmitters) cannot be programmed into both receiver channels 1 and 2.

NOTE: If the receiver’s LED lashes continuously when a transmitter isn’t being activated, the receiver is too close to an electrical noise source. Move the receiver away from the noise source or call technical services for assistance.


Linear radio controls provide a reliable communications link and fill an important need in portable wireless signaling. However, there are some limitations which must be observed.

For U.S. installations only. The radios are required to comply with FCC Rules and Regulations as Part 15 devices. As such they have limited transmitter power and therefore limited range.

A receiver cannot respond to more than one transmitter signal at a time and may be blocked by radio signals that occur on or near their operating frequencies, regardless of code settings.

Changes or modifications in the device may void FCC compliance.

Infrequently used radio links should be tested regularly to protect against unidentified interference or fault.

A general knowledge of radio and the vagaries should be gained prior to acting as a wholesale distributor or dealer, and these facts should be communicated to the ultimate user.


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Comments: - Owned by 1st Garage Door Openers, Inc., an independent family owned and operated business serving the Garage Door and Garage Door Opener Industry since 1981. Providing excellent customer service and assistance for over 25 years. We are a discount reseller of garage door opener remotes, repair parts, keyless entry and gate operator controls for your home, business, or gated community. We carry parts for the following garage door openers: Lift-Master, Chamberlain, Sears Craftsman, Access Master, Sears Best Craftsman, Sears Automatic Door Opener, Master Mechanic, Security +, Formula 1, Garage Master, Billion Code, LiftMaster Professional, Estate Series, Premium Series, Contractor Series, Power Driver, Whisper Drive, Genie, Alliance, Norelco, Blue-Max, Lift-A-Door, Pro Max, Hercules, Stealth, Excelerator, Intellicode, Genie Pro, OverDrive, Python 2, Signature, Phantom, Legacy, Medallion, CodeDodger, Overhead Door, Genie Shop Vac, Stanley, Vemco, Quiet Glide, SecureCode, Lightmaker, Innovative Products, Whistler, U-Install, Popular Mechanics, Allister, Allstar, Pulsar, MVP, Challenger, GTO, All-O-Matic, Electrolift, Westinghouse, AM/11, Linear, Access Pro, Moore-O-Matic, MegaCode, Delta 3, MultiCode, Heddolf, ESP Micom, Intercontinental Dynamics, Crusader, Wayne Dalton, iDrive, Door Master, Quantum, Classic Drive, Tec Key, Martec, Monarch, Telectron and other garage door openers, and gate operators. Brand names of Garage Door openers are registered trade names of the respective entities and are only used for reference.