Installing a Cobra 75 WX ST / CB Radio in a 2006 and Later Miata MX-5
by Myron Martwick

This installation was done by Myron Martwick in a 2006 Nordic Green MX-5/Touring Model

What makes this installation relatively easy is the all the panels have snap fastenings or clips into slots on the metal car frame. When you examine the interior panels of the M3 it is obvious that an order of panel removal is necessary since the edges of the panels overlap onto other panels. The installation requires the complete removal of the back panels of the passenger compartment, the passenger side door kick plate, loosening of the center console, the panels in the trunk on all sides except the driver’s side, the wind screen and the coverings of the roll bar hoops. This is not as difficult as it sounds. The total cost should not exceed $ 200 unless the rear speakers are needed.

Myron Martwick would be available to assist any member wanting to do this installation.

1. The Cobra 75 WX ST (Fig 1) is small, convenient and has sufficient power for all Mt Hood Club activities and events. This installation uses the rear speakers on the back panel of the M3 Miata as external speakers for the CB. The proximity of the speakers to both the driver and passenger gives sufficient volume so that CB transmission can be heard over road noise. The installation allows for the switching of the speakers between the Audio System and the CB radio. Components can be purchased at Radio Shack and Napa Auto Parts. M3 models without factory rear speakers will have to have those speakers installed. Kits may be purchased and installed as part of this procedure. The Audio System Speakers are prewired with a plug behind the rear panel and the installation is simple once the cockpit panels are removed.

2. The installation requires installing two relays to switch the speakers between the Audio System and the CB. These relays can be mounted in the trunk behind the right hand panel and towards the front from the removable side panel for the tire jack( Fig 2). The switch for the relays is mounted in the snap out tray at the front of the center console just below the AC & Heater Controls. A lighted rocker switch is recommended so you know when the switch is activated

3. Power for the CB and the relays can be wired from the 15A fuse for the AUX jack in the instument panel (Fig 3). The location of this fuse can be found in your Owners Manual. This fuse adapter can be ordered from NAPA Auto Parts. Note the red power lead coming from the top of the fuse. This adapter is simple to install since it goes in the same fuse spot as the AUX and hass two of it’s own fuse holders, one for the AUX and one for the CB.

4. The power and speaker control box can be mounted in the passenger’s foot well on the door side using Velcro on the hard surface (Fig 4). This placement allows for easy access and installation of the antenna and external speaker wire that are installed under the kick plate of the passenger’s door. It is also easy to fish the power wire across from the fuse box on the driver’s side.

5. The relay switch and handset connector are mounted in the tray just in front of the gear shift lever (Fig 5). This tray just pops out. It allows for easy access to fish the control cable from the control box and the power wires to and from the relay switch. The power lead from the relay switch is fished down through the center console.

6. When beginning the removal of the passenger compartment panels move both seats forward as far as possible. All the panels in the back of the passenger compartment are fastened with snap ins ( Fig 6) and are easily released by just using your finger nails. The door sills, hoop and wind screen removal can be done using putty knife 1 ½ - 2 inches wide. The windsreen is held by 4 hidden snaps. The hoops must also be removed. The front black pieces snap off and the silver back pieces are held by phillips srews that are revealed when the black front pieces are removed.

7. The center console has a screw hidden under a snap out at the bottom of the forward cup holder (Fig 7). This can be removed with a flat screw driver. The screw holding the console has a Phillips head. This must be loosened to allow for the removal of the back panels and to fish the wire from the relay switch through to the trunk.

8. The CB Handset unit can be stored in a fishing reel bag (Fig 8) and put in one of the storage compartments on the back wall. I store mine on the driver’s side

9. The antenna can be unscrewed from the base and stored in a PVC pipe with one end cap gluded in place and the other end removable ( Fig 9). The base can be stored in the trunk by attaching it to the metal under surface of the trunk deck.

10. The magnetic mounted antenna can be placed on the trunk deck between the trunk lid and the space for the top ( Fig 10).

List of materials and Tools

1. 1 – Cobra 75WSXT CB Radio /

http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2015298/p-2015298/N-111+10201+600000508/c-10101/ $91.00

2. 1 – Magnetic Mount VMT CB Radio Antenna/ http://www.buyreliant.com/cbantenna/magnetic_antennas.htm / $27.00

3. 2 – Relay/w socket DPDT / Radio Shack Part# 275-0206 / $9.49ea.

4. 1 – Lighted Automotive Switch / Radio Shack Part# 275-772 / $3.99

5. 1 - Rainbow wire 20’ roll, Radio Shack Part# 278-858 / $5.99

6. 1 – 90’ roll - 3 Color/22 ga. Solid Hook Up Wire / Radio Shack Part# 278-1221

7. 1 - Fuse Adapter Napa Auto Parts / $ 20.00,

8. 1 - 1” wide Velcro / 1 Foot

9. 1 - 4” square of hard packing foam

10. 1 – Soldering Iron & rosin core solder

11. 1 – Small Straight Slot Screwdriver

12. 1 – Medium sized Philips Screwdriver

13. 1 – Wire Cutter & Stripper