Associated model number: 4120

Congratulations! You have just purchased a MULTI-CODE Digital transmitter, which we believe to be the finest product of its kind on the market. With little care this transmitter should provide you with many years of excellent service. Please take a moment to read the following instructions and you will find that setting your new transmitter will be quite an easy matter.


On the model 4120 transmitter the entire front lower half of the case is removable by inserting a small coin in the slot provided with a twisting motion. Once opened you will have access to both code switches and the battery compartment.


Before placing your transmitter into service, we urge you to set your codes, in order not to interfere with neighboring systems, and to provide security for your own system. You will note that the model 4120 transmitter has two, ten position code switches. We strongly urge that several coding schemes be avoided: ALL ON; ALL OFF; 2,4,6,8,10, ON; 1,3,5,7,9,ON. These positions are similar to our or other manufacturer’s test positions, or are frequently used.

If you have two single channel receivers: Set your transmitter to that the ten position switch on side A will match your receiver #1. Set the ten position switch on transmitter side B to your receiver #2.

If you have a MULTI-CODE 3021 or 3028 two channel receiver: Set the receiver and transmitter (side A and B) code switch positions 1-9 to match. The 10th position on your transmitter code switches are used to channel selection. Channel 1 on the receiver is selected by moving the 10th position of the transmitter side A to the off (open) position. Channel 2 is selected by moving the 10th position of the transmitter side B to the on (closed) position. Once the codes have been set, check the operation and replace the lower cover.


The transmitter is completely self contained, including battery, and can be opened while mounted in the car. It is supplied with a clip for attaching to the sun visor, if desired. If the clip is used, attach to the case by sliding it into the recess provided on the back of the transmitter until the small dimples fir into the holes in the clip.


ALL MULTI-CODE door related products carry a eighteen (18) month warranty against defects in workmanship or material. This warranty begins at the date of manufacture, for eighteen months. Linear Corporation warrantees our product only to authorized dealers and distributors and not to the end customer. If you have any questions about our warranty, please ask your dealer to determine the nature and scope of his warranty. Linear Corporation does not assume, and is not responsible for, any real consequential damages from claims against the performance of our product, nor is it liable for any costs related to loss of life, property, or revenue. Further, Linear Corporation is in no way responsible for installation of our product, and will assume no costs related to reinstallation or removal. Linear Corporation’s warranty is in lieu of all other warrantees, expressed or implied.


Linear Corporation has devoted a great deal of time and research in order to provide the most reliable equipment possible. Certain limitations must be observed.

  1. MULTI-CODE radio components must conform with FCC Part 15 requirements. For this reason. the range and power of our radios is within specified limits.
  2. As with all manufacturers, Linear Corporation’s radios must accept all signals that they receive. This may, in rare instances, create difficulty.
  3. You should test your entire system occasionally in order to be sure that all components are working in good order.
  4. Linear Corporation’s dealers can provide you with information regarding the use of our radio controls, and can provide valuable installation and operation information, when requested.

Caution: Any changes or modification in intentional or unintentional radiators which are not expressly approved by Linear Corporation could void the user’s authority to operate this equipment. This applies to intentional and unintentional radiators certified per part 15 of the F.C.C. rules and regulations

2055 Corte del Nogal
Carlsbad, CA 92009


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We invite your inquiries regarding your garage door opener.

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(located on motor head behind light bulb cover)
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(located on back of remote)
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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.