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Installing a Hidden CB Radio in your Car by Julian Edgar You can improve your safety and convenience when driving on country roads with a near-invisible radio. Shown here is a GME all-in-one CB radio. Using this type of design means you only need space on the dash or centre console for the handheld microphone. The rest of the electronics is housed in the small box that is easily tucked away. M any people don’t realise that having a CB radio in a car can be very beneficial, especially in rural Australia. Such a radio can be nearly invisible, both in terms of occupying dashboard space and the presence of the antenna. Safety and convenience Nearly every truck in Australia is fitted with a UHF CB radio. They’re used by the driver when the truck is entering a building site (that’s why you see signs like “UHF 21” on entrance gates to such sites). More relevant to us, on country roads, they’re set permanently to Channel 40. Unlike in old movies (“Breaker, breaker, got a copy Big Bear”), truck drivers mostly talk about road hazards, warning other trucks of the problems they’re about to encounter. This makes listening on a CB radio incredibly useful for anyone who drives on rural roads. I have used CB radios in nearly all my cars of the last 40 years and, over that time, I have been warned 82 Silicon Chip of thousands of road hazards. That includes car and truck accidents, floods, vulnerable touring cyclists, vehicles broken down but not sufficiently pulled off the road, road works, wide loads, trucks with dangerously loose tie-down straps and chains – the list goes on and on. I have also used the radio to tell trucks their rear lights aren’t working, to warn them of hazards I have seen that await them, and on one memorable occasion, to request a pickup from my broken-down car, at night and over 100km from the nearest town (yes, a truck stopped!). Unlike amateur radio, no license is needed for CB radio operation. You simply buy it, fit it and use it! To anyone used to operating a radio in a formal situation, truckies on CB might sound like anarchy in action – but it isn’t. In fact, the communication is strongly codified by tradition. It’s in cities where (unfortunately) every idiot is on the radio screaming meaningless rubbish. Over time, you get used to listening Australia's electronics magazine for the tone of communications, the radio just burbling away in the background. A driver saying hello to a friend who he (they’re nearly always male) has seen travelling the other way has one tone; the escort vehicle of a wide load warning other trucks that the load is coming through has a quite different tone; and a warning about an accident has a different tone again. As an example of the radio in action, the other day I drove from my home north of Canberra down the Barton Highway towards the city. When I turned onto the highway, I immediately knew that something was up; I heard a snatch of conversation where a driver was asking if traffic was being allowed through. That gave me an indication that there had been an accident and the road may be closed. So it proved. As I got closer, the radio chat increased until, by the time I reached the stopped traffic, I knew the type of vehicles that had been in the accident, the length of the traffic jam and the likely duration of the siliconchip.com.au A UHF CB radio installed on the dash of my MG4 electric car. Glass-mount CB radio antennas are unobtrusive and can be installed in minutes. The antenna cable connection is via a small box that sticks to the inside of the glass – no holes are needed! delay. Coincidentally, as I got to Canberra, there was a further delay; this time I asked what the problem was and was immediately told there had been another car crash. A stealth CB installation Most people don’t want a gigantic antenna on their car – there’s also the hassle of fitting it, trying to get a cable into the cabin and also finding space on the dash for the radio. Luckily, you don’t need any of that. There are two approaches that make fitting a largely invisible CB radio quite easy. The first is to use a glass-mount antenna. As its name suggests, a glass-mount antenna sticks to the front or rear glass of the car. Normally, you place it on the windscreen, high up near the roof. The antenna comprises just a very short whip (typically 200mm long) with a small mounting square at its base that sticks to the glass with strong double-sided tape. Attaching this takes, oh, about 30 seconds! Clean the glass, peel off the backing tape, stick it into place. So, how does the cable connect to the antenna? Don’t you have to drill a hole through the windscreen? No; instead, the connection through the glass is made by RF, with a little rectangular box stuck inside the windscreen at the antenna’s location. To run the small-diameter antenna cable to the box, you simply tuck the cable behind the roof headlining and then down behind the A-pillar moulding. Typically, the provided cable siliconchip.com.au doesn’t need to be cut – any surplus length is just coiled out of sight. Editor’s note – this cable route is also suitable for the power cable on many dash cams. The second approach is regarding the radio itself. The trick is to use a 5W radio where the microphone is an ‘all-in-one’ control. That is, the microphone is also the speaker and has all the radio’s controls and displays on it. Radios of this design have a separate box that houses the main electronics, small enough that it can be easily tucked behind the dashboard or centre console – yes, even in current cars. All you then need to do is to find a source of power (invariably I access this at the back of the cigarette lighter/ accessory power socket) and find a place to mount the compact microphone on the dash or centre console. The radio will have an inline fuse in its power feed, so you don’t even need to add a fuse. Don’t cut the wires at the cigarette lighter socket; just bare a short length of the positive and negative leads and solder the power and ground leads of the radio appropriately. Having said that, you should pull the cigarette lighter fuse first and thoroughly insulate all connections with tape before restoring it. Compared to installing a traditional CB radio and antenna, especially in modern cars, the process is quick and easy. In the past, the bane of a CB radio was engine ignition noise, which can be very annoying and is often quite hard to get rid of. However, in my experience, modern cars are much less likely to generate such noise. My current car, an EV, generates no audible RF noise at all (not even from the inverter) – something I was not sure about before fitting the radio. Conclusion A glass-mount antenna and all-inone CB radio will cost more than a traditional CB antenna and radio. It also won’t have the reception or transmitting range of a large antenna mounted on a bull bar, but it will be absolutely fine for monitoring road conditions and talking to nearby vehicles. If you drive on country roads, a CB is a must-have for safety and convenience. Using an all-in-one radio and glass-mount antenna means that only the closest of observers will even realSC ise you have a radio on board. Squelch and transmission range All CB radios have an adjustable squelch control that quietens the radio unless a signal is received (ie, someone is talking). This means that for much of the time, the radio is silent – it’s not a continual distraction or annoyance. Also, because of the limited range (less than 5km for the set-up described here), when someone does talk, it’s often relevant. Australia's electronics magazine May 2026  83