The Linear F310 / Mighty Mule FM137 is a programmable digital access keypad designed for compatible automatic gate operator systems. The keypad can be used as a wireless 318MHz access device with supported receivers or connected directly to compatible gate operator control inputs for hard-wired operation.
Linear currently identifies the professional version as model F310. FM137 is the Mighty Mule/GTO designation commonly associated with the same keypad family. Because these products have been produced across multiple operator and control-board generations, verify the exact model and installation method before using one designation as a direct replacement for another.
The F310 / FM137 allows authorized users to activate an automatic gate by entering a four-digit PIN code. Up to 25 entry codes can be stored, allowing different codes to be assigned to family members, employees, service personnel, contractors, or other approved users.
Temporary codes can also be programmed to automatically expire after 1-7 days. This is useful for short-term access without permanently sharing the master or primary entry code.
The keypad supports both wired and wireless installation depending on the gate operator and control-board configuration.
Compatibility warning: A gate operator using a different frequency, receiver generation, radio format, or control-board input may require wired installation, a compatible external receiver, or a different keypad.
Do not assume wireless compatibility with every Linear, GTO, Mighty Mule, Nice, garage door, or gate operator simply because the equipment has a radio receiver.
| Brand Family | Linear / GTO / Mighty Mule / Nice |
|---|---|
| Linear Model | F310 |
| Related Mighty Mule Model | FM137 |
| Product Type | Digital gate access keypad |
| Installation | Wired or wireless depending on operator |
| Wireless Frequency | 318 MHz |
| PIN Capacity | Up to 25 entry codes |
| PIN Length | 4 digits |
| Temporary Codes | Programmable for automatic expiration in 1-7 days |
| Battery Type | 3 AA batteries |
| Batteries Included | No |
| Wireless Range | Current FM137 manual recommends no more than approximately 50 ft from receiver; actual range varies by site |
| Wired Output | OUT / COM low-voltage control connection |
| Keypad Feedback | Illuminated keypad, status LED, and audible beeper |
| Incorrect Entry Protection | Approximately 40-second lockout after excessive unmatched key entries |
| Code Memory | Stored codes remain in memory if batteries lose power |
| Enclosure | Weather-resistant outdoor keypad housing |
The F310 is currently listed by Nice/Linear as the Linear digital keypad for LinearPro/GTO gate operator applications. FM137 is the Mighty Mule keypad designation. The products are commonly cross-referenced because they share the same basic 25-code wired/wireless access-control application.
Do not rely on the cross-reference alone when replacing an older keypad. Radio programming methods, operator receivers, control boards, and production generations have changed. Verify whether the installation requires an F310, FM137, newer Mighty Mule keypad, or hard-wired connection before ordering.
The keypad supports temporary four-digit entry codes that can automatically expire after a selected period from one through seven days. This allows temporary access to be provided without deleting or changing permanent user codes after the visitor no longer needs access.
The FM137 uses a 318MHz radio transmitter in wireless mode. Some older systems use DIP-switch transmitter coding, while newer compatible Mighty Mule operators provide a learn procedure through the operator control board.
Frequency alone does not guarantee compatibility. Verify the receiver technology and operator generation before assuming that any 318MHz gate receiver can learn the keypad.
Current FM137 instructions provide an OUT and COM connection for direct low-voltage activation of compatible gate operator control inputs. A typical compatible operator uses a CYCLE or similar activation input together with COMMON.
Never connect the keypad to an unknown terminal based only on wire color or physical location. Use the gate operator wiring diagram and confirm that the input is intended for a normally open access-control activation device.
These references are commonly associated with this keypad family. Production date and operator generation should still be checked when replacing an existing unit.
Three AA batteries are required and are not normally included. Low-voltage direct-burial wiring, mounting posts, external receivers, and other gate accessories are not automatically included unless specifically stated in the product package.
If a keypad works when hard-wired but not wirelessly, do not immediately replace the keypad. Check receiver compatibility, transmitter programming, receiver antenna condition, installation distance, interference, and battery condition first.
If an existing older keypad is being replaced, identify whether the gate currently uses the keypad wirelessly or through OUT/COM wiring. That distinction can change which replacement keypad or receiver is appropriate.
Mount the keypad where a user cannot reach through, around, or over the gate to activate it while contacting the moving gate. The keypad should not be installed inside an entrapment zone or where activation requires a person to stand in the gate's path.
Do not bypass photo eyes, safety edges, obstruction sensing, emergency access, or other required entrapment-protection devices when installing an access-control keypad. If the operator wiring or control input is unclear, have the installation completed by a qualified gate or access-control technician.
The F310 and FM137 are closely related 25-code wired/wireless keypad models and are commonly cross-referenced within the GTO, LinearPro, and Mighty Mule product family. Because production generations differ, verify the existing keypad, operator, receiver, and wiring before treating them as a direct replacement in every application.
The keypad can store up to 25 four-digit entry codes, including codes assigned to individual users. Temporary entry codes can also be programmed for short-term access.
Yes. Current FM137 documentation identifies a 318MHz transmitter for wireless operation. The receiver must still be compatible with the keypad's radio system and programming method.
Yes. Compatible installations can use the keypad's OUT and COM connection to an appropriate gate operator activation input. Verify the operator wiring diagram before connecting the keypad.
Current FM137 installation documentation includes wireless programming procedures for MM371, MM372, MM571, and MM572 operators. Verify the exact operator and control-board generation before ordering because compatibility information can differ between older keypad revisions.
The keypad requires three AA batteries. Batteries are normally not included, so confirm package contents before installation.
No. A matching frequency alone does not guarantee compatibility. Verify the receiver type, radio coding method, operator model, and programming procedure before ordering for wireless use.
Check the keypad model, operator model, control-board generation, receiver type, 318MHz compatibility, DIP-switch or learn-button programming method, existing wiring, and whether the keypad is being used wired or wireless.