New Dash Modifications

I recently aquired a CB for the 109. I got it very cheaply from a member of a forum I frequent, but it’s in as-new condition. This is to be fitted to the MudStuff centre dash, as I don’t have room for it on the roof and want a tidy appearance. I had hoped to fit it in the slot between the stero and the Carling Technologies switches at the top of the dash, but the CB is too long and hits the sloping section of the original fascia panel. It looks like I’ll be able to move the stereo up into that middle position and use the bottom slot for the CB, which will have the advantage of keeping the hand mic cable out of the way of the stereo. The switch panel will stay at the top (probably), which is the preferred option as it allows easier use of the switches while driving and also keeps the stereo in a low horizontal position, so its screen is viewed from above; that’s important on most stereos as when viewed from below their axis of mounting, the screens become far less clear due to the LCD polarisation being on the wrong plane.

I’m only part of the way through fitting the CB. I have attached the antenna to the front ccntre of the roof rack, as on Camel Trophy Defenders. Mounting the antenna centrally to the steel structure is important as it ensures omni-directional signal strength. mounting to one side will give poor signal strength to that side while allowing a strong signal on the opposite direction. Obviously, the antenna can’t be mounted in the centre of the rack – it’d get damaged by any load put up there and would get in the way, so I’ll have to accept reduced range to the front of the vehicle. Range should still be acceptable in that direction, though. I have run the cable to the centre dash, the power supply is connected to the auxilliary battery bus, and I have wired up the speaker output to connect to the stereo’s front right speaker, since the CB’s integral speaker will be of little benefit tucked inside the dash. This was done by routing the stereo’s front right output and the CB output to a double-pole two position ON/ON switch, which selects which source the speaker is connected to. That means that neither source can damage each other by backpowering the others’ output and the speaker won’t be damaged by conflicting or combined outputs. It also means I can have both sources on, just losing a little stero quality. I’ll post some photos once it’s finished. That will mainly involve setting the antenna length while testing with a SWR meter – I need to remove the meter once the antenna is tuned, so I won’t be able to secure the dash until that’s done.

While tackling the centre dash, I decided to take on those Carling Tech switches. I have never been happy with their illumination, which is done by yellowish-white incandescent bulbs. Later switches have the option of coloured LEDs. I didn’t want to go to the expense of replacing these perfectly servicable switches with new, so set about fitting LEDs. I sourced batch of 5mm LEDs from my local Maplins. I’m using green for the switch identifiers and red for the system status light in the switch (they didn’t have any amber, but red actually looks rather good). Unfortunately, most commonly available LEDs are 5V, so I have had to use a large resistor for the parallel wired green LEDs and individual resistors inside each switch for the red LEDs to drop the vehicle’s voltage to below 5V (I tried connecting a spare LED to the power source and it blew). Thankfully, Maplin have an in-store computer system that will calculate what resistors are required to drop any system voltage to the required level, with entry fields for how many LEDs there are, whether they are in parallel or series, and the resistance of any other part included in the circuit. That makes it simple and reliable for their staff to pick out the specification of resistors needed for the task.

The switches have all been modified and refitted. The total cost was less than buying just one new switch and once I knew how to do it, it only took about ten minutes per switch. The LEDs will draw much less current than the bulbs (not that they drew much either), but will generate much less heat. They should also be brighter and have much better colour consistency, unlike the bulbs which I’d had to cover with green glass paint (which eventually starts to flake off). I’ll post photos of their illumination too, once the CB is fully fitted.