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RC4 Knowledge Base

LumenDim Micro External Antenna Connection (LumenDimM2micro, LumenDimM4micro, LumenDimPixMicro)

RC4 LumenDimxxmicro devices (LumenDimM2micro, LumenDimM4micro, LumenDimPixMicro) can be configured to use either the built-in chip antenna (“internal antenna”) or a wired antenna connected to a u.fl connector (“external antenna”).   For most models, antenna type can be changed in the field with precision soldering skills.  Making this change does not void the product warranty, but damage to the board caused by poor workmanship does void the warranty.  In other words, if you are experienced with small electronic soldering, you’ll be fine.  Otherwise, leave this to someone who will do it properly.  :)

There are two revisions of the original RC4 LumenDimM2micro.  The original version is a green circuit board, version R1.2 SEP2015.  It is constructed to use the on-board chip antenna by default; the u.fl antenna connector is not active and attaching an antenna to that connector will NOT result in any performance improvement.  The chip antenna is the small white block at the corner of the TiMo.  R1.5 NOV2019 is a white circuit board.  It is constructed to use the u.fl antenna.  By default, the on-board chip antenna is not active.

Board color refers to the primary larger board, not the LumenRadio TiMo RF module.  The RF module is usually green but is sometimes black.

The TiMo radio module is switched between the two antenna modes by jumpering pins 5 and 6 on the module.  The R1.2 green boards have these pins jumped on the board, below the module.  This makes it difficult to modify for use with an external antenna.  On special request, RC4 manufactured external-antenna versions of the 2micro by modifying the circuit board prior to assembly.  Those devices can be switched back to using the internal antenna by adding a jumper as described below.

Do not try to modify an original green RC4 LumenDimM2Micro that uses the internal antenna unless it already has (or had) a jumper added by RC4 at the factory.

The white boards for all RC4 LumenDimxxMicro devices leave pins 5 and 6 open on the board.  This makes it easy to add a jumper to select the chip antenna.  With either a modified M2micro R1.2 board, or any white micro board, a simple modification selects the active antenna type.

For external antenna via u.fl: NO jumper, no connection between pins 5 and 6.

For on-board chip antenna: a jumper should be added between pins 5 and 6.

Here is how the pin counting works:

This image shows both versions (old green, and new white), with the jumper added.  The green one has been factory modified, it is not the stock version.  With the jumper added, these units use the on-board chip antenna, not the u.fl conector:

And here, we see these same units with the jumper removed.  Remember, the green unit here has been modified so that pins 5 and 6 are no longer connected on the circuit board below the TiMo RF module.  These units now both use the u.fl antenna.  They will not perform well without an antenna connected.  You must use an external antenna with these:

When using an external u.fl antenna, the metal connector should NOT touch the small capacitors positioned on both sides of the u.fl connector on the TiMo.  This is correct:

PRO TIP: You can add a small amount of hot glue or silicone seal around the antenna connector to ensure it doesn’t move.

Below are examples of what to NOT DO.  These antenna cable positions are BAD because the metal connector is touching other components on the TiMo board.

Connector touching capacitor at left.  THIS IS BAD:

Connector touching capacitor at right.  THIS IS BAD:

If you need additional assistance, please open a support ticket.  We respond very quickly, this is the very best way to get help with RC4 devices.

Thank you, and happy micro dimming!