Answer first: fit the magnetic omni on the roof centre-front where it sees the widest sky, run the 5 m feed through the door seal rather than across the moving door hinge, plug the roof lead into the BS port and the 3 dBi whip into the MS port, power the chassis from the 5V DC cigarette lighter after the donor antenna is mounted, read the green LED, and test calls and browsing across the cabin with up to 15 handsets; the whole job takes under 15 minutes with no tools, and a weak rural donor triggers the optional fishtail directional aerial upgrade while a permanently sited static caravan can run from a 240V AC mains adapter. The CVCG suits an O2 or Vodafone driver, crew or touring camper whose calls and data drop inside the metal cabin; it does not carry EE 2G voice on Band 3, does not tune 3G Band 1, and does not do 5G.

What Comes in the CVCG Kit Before You Start

Before the first panel lifts, confirm the kit matches the install plan. The standard CVCG box contains the compact 380 g chassis measuring 150×100×28 mm, the magnetic-mount 5 dBi omni roof antenna, the 3 dBi interior whip, the 5 m low-loss coaxial feed, the 5V DC cigarette-lighter adapter, and the wiring loom; the fishtail directional aerial with three magnets and a 3 m coax lead is a paid optional upgrade chosen at checkout rather than a standard part.

Mounting tools you actually need

No drills, crimpers or signal meter are required for the standard install: a clean cloth to wipe the roof steel, a small trim tool or plastic card to tuck the seal, and a phone with the field-strength read-out on screen for the spot check. The magnetic base grips bare steel; a soft cloth under it protects paint and avoids scratching a company fleet van. Keep the 5 m feed coiled loosely rather than twisted, and lay the interior whip where passengers will not kick it.

Step 1: Magnetic Roof Antenna Placement for a 70mph Hold

The 5 dBi magnetic omni captures the outside donor before the metal cabin shields it, and its placement decides whether the CVCG works at all. Put it on the roof centre-front, just behind the windscreen where the panel is highest and least shadowed by rails, racking or a hard-top, rather than on the bonnet, the boot lid or a rear corner where the bodywork masks one horizon.

Centre-front and high beats rear or low

A centre-front high point gives the omni a clear 360° sky view in all four directions the vehicle travels; a rear-corner mount cuts reception on the opposite road and a bonnet mount runs the feed across the moving hinge. Clean the steel first, press the base flat, and check no rust, vinyl wrap or roof bar block lifts the magnet from the panel. At 70 mph on a motorway or A-road the strong magnet holds as long as the base is flat on bare steel; field reports from van drivers on a Scotland road trip describe the antenna staying on at motorway pace rather than sliding back.

Aluminium and fibreglass roofs: the workaround

Some vans, motorhomes and modern cars use aluminium sheet or a fibreglass roof, which a magnet cannot grip. For those, fix the magnetic base onto a small steel mounting disc bonded to the roof with a non-permanent pad, or bolt a small bracket to a roof rail or mounting point; the fishtail upgrade's three-magnet base behaves the same way and also needs a magnetic or bonded steel surface. On a fibreglass caravan roof, a bracket clamped to the ladder or rail, or a weight plate on the bonnet edge during a static stop, keeps the omni outside the metal shell while the 5 m feed reaches back inside.

Step 2: Route the 5m Feed Through the Door Seal, Not Across the Hinge

The roof antenna connects to the chassis by the single 5 m low-loss coax, and the routing keeps the wire away from moving parts while preserving the seal. Run it from the roof edge down the A-pillar or along the drip rail, then tuck it under the rubber door seal so it closes on the rubber rather than trapping the pinching edge; the door can shut fully without the cable shearing or pulling the antenna off at speed.

Door seal versus window gap

For a quick commute fit, close the cable in the seal of the front passenger door and pull the slack inside to the glovebox or under the seat; on a van or HGV, route the feed through the sliding-door seal or the rear door seal where the rubber is broadest. Where a seal trap looks tight, leave the window a finger-width open and run the feed through the gap, then close the window on the rubber rather than the wire; never run the coax across the door hinge or the scissor mechanism, where a moving edge will fray the shield within days.

Keep the feed away from power leads

Separate the coax from the 12V loom, headlights and any inverter wiring to avoid ignition and alternator noise riding the signal; keep bends broad, avoid kinks, and do not coil the spare length tightly beside the chassis, because a tight bundle can distort the field. The 5 m reach covers a family car, a panel van and a motorhome; an extra-long HGV chassis or a large caravan that exceeds 5 m should use a low-loss extension on the BS side rather than a splice.

Step 3: Chassis Placement and the BS versus MS Ports

The compact 150×100×28 mm chassis fits under the front seat, behind the glovebox, on a van dash shelf, or on a motorhome console; keep it ventilated and away from direct sun on a heated dash. The two ports are labelled, and swapping them inverts the loop and causes oscillation, so match lead to port on the first attempt.

Why port swap causes a loop

If the roof lead plugs into MS and the whip into BS, the interior whip radiates straight back into the donor antenna, the chassis feeds its own output, and the AGC drives gain toward oscillation until the LED flickers and the cabin drops. The fix is simply to swap the two leads; once BS carries the outside donor and MS carries the interior whip, the two antennas face opposite environments and the loop stays open. Keep the interior whip upright on a dash or seat side, not pressed against the roof lead.

Where the whip radiates best

The 3 dBi whip radiates the amplified field across the front seats, passenger bench and camper lounge; place it on the dash centre or the seat back rather than under a seat, where cushioning blocks the field. A rear-seat or back-berth reading may run lighter than the front row, which is normal for a single whip in a cabin; move the whip toward the middle of the occupied space rather than expecting equal reach to every corner.

Step 4: 5V DC Power, the Power-On Sequence and the LEDs

The chassis runs from the included 5V DC cigarette-lighter adapter, and the order matters: mount and connect both antennas before powering on, so the AGC does not latch into a self-fed loop the moment it wakes. Plug the lighter into the socket, switch the ignition accessory on, and the chassis lights rather than booting an empty loop.

Correct power-on order

First the roof magnetic omni is placed and the 5 m feed reaches the BS port; second the 3 dBi whip connects to the MS port; only then the 5V DC lighter adapter receives power. Powering up before the MS whip is connected lets the chassis radiate into an open port and can trigger oscillation; matching the antennas first lets automatic gain control settle on the real outside donor rather than on its own leak.

Reading the status LEDs

A steady green or bright LED on the chassis confirms both bands are locked and the AGC has settled; a flickering or red pattern points to oscillation, a port swap or a donor that is too close and overloads the input. On a rural road where the donor swings between hills, the LED may dim momentarily as the AGC rebalances, which is normal; a permanently dark LED with power present usually means a loose BS lead or a blown lighter fuse. After each move of the antenna, wait ten seconds for the AGC before judging the reading.

Static caravan and mains hookup: the 240V AC adapter

For a permanently sited static caravan or holiday home left on a pitch, the vehicle lighter socket may not be available; an optional 240V AC adapter feeds the same 5V DC chassis from the mains hookup, and a USB power bank also runs the unit where a socket is scarce. The chassis itself draws little current, so a touring camper can run it from the lighter on the move and the AC adapter on the pitch without changing the antennas.

When to Add the Fishtail Directional Aerial for Weak Signal

The standard magnetic omni works where the outside reading already lands around -90 dBm or better on the roof; where the road runs through a deep valley, Scottish glen, Welsh mountain pass or remote Cornish lane and the roof reads below -100 dBm, the omni cannot tell which distant tower to hold, and the paid fishtail directional upgrade becomes the right move.

Donor readings that trigger the upgrade

A roof reading between -90 and -105 dBm on a single visible tower favors the aimed fishtail over the omni: the directional panel focuses the narrow beam on that one mast, rejects clutter from other directions, and recovers a control channel the omni averages away. The upgrade mounts with three magnets and carries a 3 m coax lead; aim it at the tower the phone selects on the outside reading, and re-check the LED after locking the beam. Below -112 dBm, where no tower decodes at all, no vehicle aerial manufactures a signal and a dedicated external fixed system applies instead.

Do not over-aim an omni commuter route

On a daily commute past many masts, a fixed directional panel must be re-aimed as the road changes carrier, so the omni suits the commuter and taxi while the fishtail suits the long-haul HGV, remote farm road and rural touring camper that travels toward one consistent mast. The upgrade changes the capture side only; it does not raise the ≥10 dBm output past the vehicle class or extend beyond the 100 m² cabin rating.

The 15-User Cabin Test: Calls and Data Across the Space

The CVCG supports up to 15 simultaneous handsets across a 100 m² cabin or small caravan; the acceptance test checks that the front and rear rows, the passenger bench and the camper lounge all hold a call and a data session at once rather than one phone beside the whip.

How to run the test

Place mixed handsets on O2, Vodafone, giffgaff, Tesco, Lycamobile and Sky Mobile SIMs in the front seats, rear bench, passenger side and camper berth; start a voice call on one group and a browsing session on another, hold both for a minute, then walk the reading around the space. Record the bar count before fitting, after fitting at the front, and after fitting at the rear; a daily commute that went from zero bars to four or five bars in rural Wales, or a Devon caravan that streams a show and holds a call, matches the reported pattern. With 15 users on a crew van or taxi fleet, stagger calls so the AGC balances the load rather than piling every handset on the whip.

Expected coverage by vehicle type

CVCG Against the Vehicle Family: Why Band 20+8 Adds the Call

The Boost4U vehicle range splits by tuned band, and choosing a single-band model leaves either data or voice absent inside the cabin.

The CVC single-band unit keeps O2, Vodafone and Three 4G data but has no Band 8 circuit call leg, so an older O2 handset without VoLTE sees no boosted call; the CVCD on Band 20+3 carries EE voice but leaves the O2/Vodafone Band 8 call unboosted. The CVCG sits between them for the O2/Vodafone driver who needs both a data session and a normal call inside the moving cabin, with the same 45/50 dB gain and ≥10 dBm output as the class.

Troubleshooting: Oscillation, No Signal and the LED Read-Out

Oscillation: looped field and flickering LED

The symptom is a flickering or climbing LED, a reading that looks strong beside the whip but falls away a step back, and dropped calls despite power. Causes are a BS/MS port swap, the whip too close to the roof lead, or the donor antenna so near the interior whip the chassis feeds itself. Fix the ports, move the whip clear, and keep the exterior and interior antennas on opposite sides of the metal shell; AGC then settles rather than driving gain into the loop.

No signal at all: dark LED and loose leads

A dark LED with the lighter live points to a loose BS connector, a fuse in the lighter socket, or the roof antenna on a non-magnetic panel that shifted. Check the seat on bare steel, reseat both connectors, try another lighter socket, and verify the donor exists outside the car first; if the phone reads zero bars on the roof, the booster cannot recover a block absent from the tower.

Weak rear seat, dead rural stretch, and engine noise

A lighter rear seat reading comes from a single whip offset toward the dash; move it to the cabin centre. A dead valley below the decode floor needs the fishtail upgrade or a fixed system rather than another antenna inside. Hum or whine that follows the revs points to the coax running beside the power loom; separate the feed and re-check.

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