Answer first: the CD100 is a self-contained dual-band licence-exempt repeater that any home owner or flat dweller can install without an RF contractor, a drilled roof panel, or a paid frequency licence, because a 100 m2 footprint needs only one outdoor omni antenna, one indoor whip, one 10 m cable and a standard UK mains socket. The whole job breaks into ten factual stages: (1) confirm a usable outdoor 4G reading on the band your network uses, between -97 and -105 dBm, and a usable 2G voice reading where calls matter; (2) choose a window, fascia or low-roof mounting point for the 5 dBi omni at 3 to 5 m height with a clear path to the serving mast; (3) keep the outdoor omni and the indoor whip at least 10 m apart vertically so the repeater does not feed its own signal back; (4) connect the included 10 m outdoor coax to the BS (base station, donor) port; (5) upgrade that outdoor run to 20, 30, 40 or 50 m only when the chosen point cannot be reached with 10 m; (6) connect the indoor 3 dBi whip to the MS (mobile station, server) port; (7) place the amplifier chassis on a shelf or wall in the central room of the 100 m2 space; (8) connect every antenna before plugging in the AC adapter; (9) watch the LED indicators for 3 to 5 minutes while the automatic gain control locks onto the donor cells; and (10) test a voice call and a 4G speed session in the weakest room before calling the job finished. This guide explains each stage with the exact dBm ranges, heights, port labels, cable lengths, LED states and timings the CD100 needs for a 100 m2 home.

The CD100 is rated for up to 100 m2 (1,076 ft2) of indoor coverage and up to 10 simultaneous users, which places it in the single-room, small flat, studio, one-bedroom apartment, cottage, or home-office bracket rather than the whole-house or commercial bracket. It ships with a 5 dBi omni-directional outdoor antenna, a 3 dBi whip indoor antenna, a 10 m low-loss outdoor coaxial cable, and an AC 100 to 240 V 50/60 Hz adapter stepping down to DC 5 V with a UK 3-pin plug. It delivers at least 45 dB uplink gain and at least 50 dB downlink gain on both Band 20 (800 MHz) and Band 3 (1800 MHz), with maximum output power of at least 10 dBm per the Ofcom licence-exempt ceiling, a noise figure of no more than 5 dB, and UKCA, CE and RoHS certification. No frequency licence and no annual fee are required.

Before you mount anything, treat the install as a measurement job, not a wiring job. The most common support question on a 100 m2 setup is not an amplifier fault: it is an omni antenna tucked behind a metal gable, the outdoor run left at 10 m when the mounting point sits at the back of a terraced garden, a swapped BS and MS cable, a pair of antennas sitting on the same wall within a few metres, or an outdoor 4G reading that was never inside the workable -97 to -105 dBm range. Working through the ten stages below in order avoids those mistakes, and the 10 to 15 minute estimate assumes you already own a phone in field-test mode, a step ladder, and a few cable ties; surveying the front, rear and side windows happens before the clock starts.

Quick Answer: Can You Install the CD100 Yourself in 10 to 15 Minutes at 100 m2?

Yes. The CD100 is designed as a DIY licence-exempt repeater and the manufacturer quotes a 10 to 15 minute installation time for a single competent person on a single room, small flat or home office, because mounting, cabling and power are the same physical steps as on a larger unit; only the survey and the weak-room test take longer in a tricky rural property. The numbered facts below set the baseline before you touch the kit.

1. Outdoor 4G signal must be present on your network's band. A usable 4G LTE reading sits between -97 and -105 dBm; below about -110 dBm the LTE receiver loses the control channel. A usable 2G voice reading for calls sits roughly between -85 and -100 dBm. Read the values in field-test mode rather than trusting subjective phone bars.
2. Mount the 5 dBi omni at 3 to 5 m height. A window frame, fascia bracket, drainpipe clip or low roof edge all work; that height clears hedges, neighbouring fences, porches and single-storey extensions that scatter the 800 and 1800 MHz waves inside a 100 m2 footprint.
3. Maintain at least 10 m of vertical separation between the outdoor omni and the indoor whip. Less than that feeds the re-radiated signal back into the donor antenna and triggers oscillation protection on both bands at once.
4. Use the supplied 10 m outdoor cable as the starting point. Upgrade to 20, 30, 40 or 50 m low-loss outdoor cable only when the window or roof mounting point cannot be reached with 10 m; on a small flat this upgrade decision is the most common ordering error.
5. Plug the outdoor antenna into the BS port and the indoor whip into the MS port. BS means base station (donor) and MS means mobile station (server); swapping the two produces no signal and confuses the automatic gain control on both bands.
6. Place the amplifier chassis near the central room of the 100 m2 space so the 3 dBi whip reaches the living room, bedroom, kitchen or desk without stretching the indoor lead past its useful length.
7. Wire both antennas first, then power on. Seat every connector, check the BS and MS labels, and only then plug the AC 100 to 240 V adapter into a UK mains socket.
8. Watch the LED indicators for 3 to 5 minutes while the automatic gain control locks onto the donor signal on Band 20 and Band 3. A steady green band light means gain settled; a flashing amber light means oscillation or a weak donor.
9. Test every zone, not just reception. Place a voice call on your SIM and run a 4G speed session in the weakest corner of the 100 m2 space, such as the bedroom above the stairwell or the desk by the external solid wall.
10. Upgrade to a directional high-gain Yagi only for weak outdoor signal. If the omni reads below -105 dBm at every survey spot, the optional high-gain directional antenna focuses more donor energy toward the serving mast; do not buy it on urban signal where the omni already reads well.

These ten points are the skeleton. The sections below expand each one into measurable steps, numbers and troubleshooting checks, and the comparison table later in this guide shows which optional upgrades are justified for a 100 m2 home and which are unnecessary.

Step 1: Check the Outdoor 4G Signal with dBm Readings Before Mounting

A repeater can only amplify what the donor antenna receives. If the window or roof position has no usable signal on your network's band, no amount of gain at >=45 dB uplink and >=50 dB downlink can manufacture that band out of nothing. The pre-install survey therefore happens before climbing the ladder, before ordering a cable upgrade, and before fixing the bracket. In a 100 m2 home the survey matters because the serving mast often sits on the road-facing side of the property while the living room and bedroom face a rear garden, and the band your SIM uses may sit on a different tower than the band a neighbour's phone shows.

The dBm ranges the CD100 expects at the outdoor antenna

Walk the boundary of your property with the phone screen visible and read the received signal strength in field-test mode. The CD100 amplifies two independent services, Band 20 4G and Band 3 4G plus 2G voice, so you read the band your own network actually uses rather than trust the subjective bar count shown on the home screen.

Interpret the numbers as a scale from strong to unusable

-97 dBm on 4G is a healthy reading that the omni will turn into a loud indoor signal once the >=50 dB downlink stage restores wall loss. -105 dBm on 4G sits at the edge of the recommended band but still produces a stable LTE session once amplified, because the CD100's downlink budget absorbs plasterboard, brick and double-glazed loss. -112 dBm on 4G is the practical floor: below roughly -110 to -112 dBm the LTE receiver loses the control channel, the phone falls back to a slower service or shows no service, and no booster can manufacture a donor cell that the outdoor antenna never receives. The >=50 dB downlink margin absorbs wall and floor loss inside the home, but it cannot invent a band the omni position never picked up.

How to read dBm rather than bars

Phone bars are subjective and differ between iPhone and Android; the dBm figure is the measurement the amplifier actually sees. On an iPhone, enter field-test mode from the dialler and watch the RSRP or RxLev value while standing still, then move around with the screen visible. On Android, use the engineering or network diagnostics menu under About Phone, or a free field-test app that lists serving-cell RSRP by band. Hold the phone away from your body, because a hand and head absorb 3 to 5 dB, and read the value on the road-facing side rather than the rear garden if the mast sits on the road side.

Where to survey: front, rear, sides and each window

Stand at the front gate, the rear fence, each side wall, and at the proposed window or fascia position. Record the reading at each spot for your own SIM, because the strongest combined spot is where the omni goes. On many UK terraced houses the front window reads well on Band 20 but the kitchen side reads better on Band 3 because a different mast serves that direction; the omni does not focus, so any clear side works, but the strongest spot always wins. On a rural cottage the field-side gable usually beats the wall sheltered by a mature hedge.

Survey warning: if your band reads below -112 dBm at every outdoor position on your land, the CD100 cannot manufacture that band indoors. You may still improve voice or the other network's service, but the missing band stays missing. In that case raise the mounting point, add height, or consider the optional high-gain directional Yagi before committing rather than drilling twice.

Mounting the 5 dBi Omni Antenna: Window, Fascia or Low Roof at 3 to 5 m Height

The 5 dBi omni-directional outdoor antenna collects signal evenly from all horizontal directions rather than focusing a narrow beam like a Yagi. That makes it forgiving for a home install: you do not need to align a bearing to the mast, only to clear obstructions and reach usable height. Its usefulness depends on two geometric choices, the mounting height and the clearance around the antenna, and both are set during the survey rather than after fixing.

Window mounting for flats and rented homes

For a flat above a shop, a top-floor apartment or a rented property where roof drilling is not allowed, clip or strap the omni to the outside of a clear window frame, a balcony railing, or a drainpipe using the supplied bracket and ties. Keep the antenna clear of the window's metal frame, foil-backed insulation and any nearby air-conditioning unit or rainwater hopper, because metal within 30 cm masks the omni's circular pattern. Double glazing itself costs only a few dB and is perfectly fine; a metal-coated low-emissivity pane or a roller shutter behind the antenna is not.

Fascia, drainpipe or low-roof mounting for houses

On a terraced or semi-detached house, fix the omni to a fascia bracket, wall-mast clip or drainpipe at 3 to 5 m above ground level. At 3 m the antenna typically clears hedges, fences, porches and single-storey extensions. At 5 m it clears two-storey neighbouring gables, mature tree canopies and chimney stacks that scatter 1800 MHz most heavily, because higher frequencies lose more energy when foliage and metal cross the pattern. A chimney bracket, fascia bracket or wall-mast clip all work; the deciding factor is whether the chosen point can hold the omni at that height with a rigid fixing and a clear downward cable entry.

Why 3 to 5 m rather than the highest roof

The CD100's 5 dBi omni is designed for homes, not towers, and extra height beyond 5 m adds mounting difficulty and cable length without proportional benefit once the hedge and fence line are cleared. A taller pole also increases the outdoor cable run, and every extra metre of passive coax removes signal power that the >=45 dB uplink and >=50 dB downlink budget absorbs but never returns. Mount high enough to clear the immediate obstruction, then stop.

Weatherproofing the outdoor connection

The omni itself is weatherproof, but the connector where the coax joins the antenna is not. Seal the connector with the supplied weather boot or self-amalgamating tape, angle the connector pointing down so rainwater runs away rather than into the plug, and fix the coax with UV-resistant clips rather than strapping it loosely to the bracket. The unit's operating temperature range of -10 C to +55 C means outdoor mounting through winter frost and summer sun is normal, but the connector seal is what protects that rating year after year on an exposed UK wall.

Antenna Separation: Why 10 m Vertical Distance Prevents Oscillation at 100 m2

The single most important geometric rule in this install is the minimum 10 m separation between the outdoor donor omni and the nearest indoor whip. Oscillation, also called self-feedback, happens when the whip's re-radiated signal reaches the omni and the amplifier treats it as fresh donor signal, boosts it again, and feeds it round in an ever-rising loop until the stage overloads, distorts call audio, wastes power and can raise the noise floor at the neighbour's cell. The CD100's >=10 dBm output and >=50 dB downlink gain make stable isolation important even at the small footprint.

Why the rule is vertical and measured at 10 m

The CD100 spec states a minimum antenna separation of 10 m, and the practical installation guidance treats it as a vertical distance where possible: mount the omni on the front window, fascia or roof at upper-floor height and place the whip on an internal wall or shelf in the room below and deeper inside, so the floor slab, ceiling void and internal walls sit between the two. Vertical separation through a ceiling costs far more isolation than horizontal separation across an open-plan studio, which is why a two-storey house naturally meets the rule while a single open-plan 100 m2 flat on one plane can struggle to.

What happens if separation is short

Below 10 m the per-band automatic gain control can no longer hold the loop stable. The symptom is a flashing amber oscillation LED on the affected band, a warm amplifier chassis, muffled call audio, or a 4G session that rises for a minute then collapses as the stage backs off. The fix is physical, not electronic: raise the omni, move the whip deeper into the building, or add an intervening solid wall. Software or gain dials cannot compensate for antennas radiating into each other, and the CD100 has no manual gain dial to crank anyway.

Typical 100 m2 layouts that pass the rule

A two-storey terraced home of roughly 50 m2 per floor passes easily with the omni on the first-floor front window and the whip on the ground-floor back room, each separated by the ceiling above and below. A one-bedroom flat over two floors needs the donor on the upper external window and the whip on the lower internal wall through a ceiling. A single open-plan studio on one plane uses partition walls, bookcases and internal doors as the isolation layer; do not mount the whip on the same wall as the cable entry point, and do not place the whip directly behind the omni's external wall even though 10 m feels like a generous distance on paper.

Cable Routing: The Included 10 m Coax and the 20/30/40/50 m Upgrade Ladder

The kit contains a 10 m low-loss coaxial cable for the outdoor donor run. There is no separate long indoor lead; the 3 dBi whip connects directly to the chassis, so the upgrade options apply to the outdoor run only. At 100 m2 the cable decision is the single most common upgrade question, because a rear-garden mounting point, a side extension or a long terraced elevation routinely exceeds the supplied 10 m.

The supplied 10 m outdoor cable

Ten metres reaches from a front window or fascia bracket to the cable entry point on most compact homes and flats where the amplifier unit sits in the living room, hall cupboard or under-stairs space. Route the cable along the eaves, down a drainpipe channel or through a soffit vent; avoid running it parallel to mains power leads, which injects 50 Hz hum, and cross power cables at 90 degrees where you must cross. Use a cable gland or rubber grommet at the drilled wall entry to keep weather out and the cable anchored, and use UV-resistant clips on the outdoor run rather than fixing the coax directly to metal guttering.

Keeping the indoor connection short

The whip plugs straight into the MS port on the chassis, so there is no long indoor coax to extend. Place the chassis where the whip can stand in open air on a shelf or desk rather than inside a metal cupboard, behind a computer case, or inside a drawer. Every bit of passive loss around the indoor antenna removes signal before it reaches a phone, and at >=10 dBm output the indoor budget should reach the whip intact, not spend itself in a concealed enclosure.

When to order the 20, 30, 40 or 50 m upgrade at 100 m2

Order a longer low-loss outdoor cable only when the strongest donor spot cannot be reached with 10 m. The upgrade ladder runs 20 m, 30 m, 40 m and 50 m, and each additional 10 m segment costs roughly 2 dB of passive loss that the >=45 dB uplink and >=50 dB downlink gain budget absorbs but never gives back. A 20 m upgrade suits a home where the omni faces a rear field from a side bracket and the unit sits at the front hall; 30 m suits a deep terraced house across a long floor plan; 40 m suits a pole-mounted omni at the bottom of a long garden feeding a cottage; 50 m reserves for the maximum-reach rural home. Do not over-order: measure the route along the wall and downpipe, not in a straight line on the map, because cable runs follow corners and bends.

Every upgrade length ships as the same low-loss coax with weatherproof connectors, so splicing the included 10 m into a longer run is unnecessary and an unsoldered joint between cables costs more loss than a single continuous upgrade. If you also add the optional surge protector on the outdoor run, place it as close to the cable entry point as practical, because a roof-mounted omni on an exposed cottage is a taller lightning target than a sheltered townhouse bracket.

BS and MS Ports: Which Antenna Plugs Into Which Socket

The CD100 chassis carries two labelled sockets. BS stands for base station port, the donor input that faces the outdoor omni. MS stands for mobile station port, the server output that faces the indoor whip. Getting this pair right is a two-second check but a swapped pair is one of the most common support tickets after poor aim and short separation, and on a 100 m2 setup a swapped pair wastes an evening of wall routing before the mistake shows.

BS (base station) = outdoor omni

Connect the outdoor cable running from the omni to the BS socket, whether that run is the included 10 m or a 20, 30, 40 or 50 m upgrade. This is the input that listens to the serving mast. The amplifier's >=45 dB uplink gain stage takes the phone's faint transmit signal, boosts it through this same path back toward the tower, and the >=50 dB downlink stage boosts the tower's incoming signal out through the MS side.

MS (mobile station) = indoor whip

Connect the 3 dBi whip to the MS socket. This is the output that re-radiates the cleaned signal to phones inside the home, covering up to 100 m2 through even gain distribution. Plugging the whip into BS and the omni into MS reverses the direction of the amplifier: no indoor coverage appears, the automatic gain control sees nothing to lock onto, and the LEDs sit dark or flash without heating up.

Connector habit

Hand-tighten each plug clockwise, then turn a further quarter turn with a spanner or pliers wrapped in cloth. Do not overtighten: a sealed connector does not need wrench force, and crushed threads leak signal on both bands at once. Check the label on the socket after tightening, not before, because the two sockets sit close together on the rear panel, and tie a small label to each cable so future moves never swap them.

Power-On Sequence and the AGC Warm-Up Period

Wiring order matters on a repeater because an amplifier powered up with no load on its ports can drive unused ports into reflection, and powering on before antennas are connected gives the automatic gain control a misleading starting point. The safe sequence below takes about five minutes and applies identically whether you fit the standard kit or a 30 m cable upgrade.

The seven-step sequence

Step one: mount the omni and run the outdoor cable to the BS port; tighten and label the connector. Step two: stand the whip and connect it to the MS port; check the label once more. Step three: confirm 10 m separation between antennas and check no metal object, fridge, radiator or bookcase sits within 30 cm of the whip face. Step four: leave the AC adapter unplugged until both cables are fully seated and every cable route is clipped down. Step five: plug the AC 100 to 240 V 50/60 Hz adapter into a UK mains socket with a UK 3-pin plug; the unit converts to DC 5 V internally. Step six: wait 3 to 5 minutes for the automatic gain control to lock onto the donor cells on Band 20 and Band 3. Step seven: read the LEDs before moving the omni; only re-aim if a band light stays dark or flashing amber.

Why the AGC warm-up is not a cosmetic pause

On first power the amplifier scans the donor spectrum, picks the strongest serving cell per band, calculates isolation against its own re-radiation, and settles gain levels that keep output at or below the >=10 dBm maximum without oscillation. Interrupting that scan by unplugging and replugging mid-warm-up forces it to restart, which is why the wait should be observed once, not repeatedly. In a home where family members keep phones nearby, power the unit on when the room is quiet so the first AGC scan is not confused by several active handsets attaching immediately.

Why not power on first

Some installers plug the adapter in to test the LED before connecting antennas. That habit finds the unit alive but gives the automatic gain control an empty port to chase, and on the next real connection the control loop can sit at an extreme gain setting until a manual cycle clears it. The seven-step sequence avoids that reset every time and keeps the first donor scan clean.

LED Indicators: What Each Light Means During Setup

The CD100 uses status LEDs rather than a smartphone app, and reading them correctly replaces the need for constant field-test checks during the warm-up. The lights split into power, donor signal and oscillation categories, and the same logic applies to both tuned bands.

Because the two bands share one antenna pair, oscillation on one band often perturbs the neighbour band's LED as the automatic gain control rebalances. Fix the flashing band first, wait another three minutes, and re-read the other light rather than chasing both at once. Near a noisy mains circuit, a dim band that stays dim despite good outdoor readings can also indicate the coax running parallel to a heavy power circuit; reroute that section at 90 degrees and restart the scan.

Zone Testing: Calls and 4G Speed Across the 100 m2 Flat or Home Office

Coverage is only proven inside the building, not on the LED panel. After the warm-up settles, walk the 100 m2 footprint with a phone on your own network and check two services in the weakest room, which is usually the bedroom above the stairwell, the desk by the solid external wall, the kitchen at the rear, or the corner farthest from the chassis.

Voice test on your SIM

Place a two-minute call from the weakest zone to a landline or a second phone and listen for muffling, echo or sudden drops. A boosted link should hold four bars of signal with clear audio throughout; dropped audio that appears only while walking near a window suggests the phone is falling back between boosted and unboosted cells, a placement matter rather than a fault. For a home office, repeat the call from the desk chair and the bedroom, because those are the two spots people call from most.

4G speed test on Band 20 or Band 3

Run a speed test in the same room and record download, upload and ping. With a donor reading between -97 and -105 dBm at the omni, expect a stable LTE link rather than gigabit speed; the goal is a usable session that loads video calls, email attachments, smart-home apps and browsing, not a competitive broadband benchmark. Walk each zone once after the test so the booster does not get blamed for a weak donor reading that was never in the workable range.

Tools, Materials and the 10 to 15 Minute Timeline

The manufacturer's 10 to 15 minute estimate assumes a standard compact flat or single-storey home, no ladder work above first-floor gutter level, and the tools below already on site. Extra time on a 100 m2 site goes to surveying each window and testing the weak room; the wiring itself is the shortest phase.

Extra items worth having on site: a weather boot or self-amalgamating tape for the outdoor connector, a step ladder rated to the working height, cable ties rather than nails through the coax, a tape measure before ordering the upgrade length, and a second pair of hands for the upper fascia bracket. Listed buildings, conservation areas and rented flats deserve a quick landlord or planning check for any external antenna, but a single small omni under permitted development rules rarely needs consent in England and Wales.

Comparison Table: Standard Kit vs Optional Upgrades for a 100 m2 Home

The table below compares what ships in the box against the paid options, so you order what the home actually needs rather than every accessory at checkout. At 100 m2 the two justified upgrades are the cable length for a distant mounting point and, only on genuinely weak rural signal, the high-gain directional antenna.

When to Upgrade from the Omni to a Directional Yagi for Weak Outdoor Signal

The included 5 dBi omni suits urban, suburban and semi-rural signal where a clear window reads -97 to -105 dBm or better. It is the right choice when you cannot identify the mast bearing, when multiple masts serve the area, or when rent and time matter more than maximum range. The optional high-gain directional Yagi becomes justified only when the survey shows a different problem.

The survey trigger for a Yagi

Walk every outdoor position and record the band reading. If the strongest spot still sits between -105 and -112 dBm at 3 to 5 m height, or the omni reads -112 dBm and below everywhere, the omni's circular pattern spreads limited energy in every direction instead of concentrating it toward one distant mast. A directional Yagi focuses gain on that single bearing, rejecting interference from the sides and rear, and pulls a usable donor out of a weak rural reading that the omni cannot lock.

Aiming the Yagi once fitted

First find the bearing to the serving mast in a survey or network app, then fix the Yagi at the same 3 to 5 m height on a clear beam path. Sweep slowly in small 5-degree steps while watching the band LED or a field-test phone, and lock the position at the strongest steady green reading. A blocked beam with a short cheap cable never beats a clear beam with a slightly longer one; if no angle clears the hedge or neighbour gable, raise the pole rather than forcing aim into a shadow.

Do not buy a Yagi on strong signal

Where the omni already reads -97 to -100 dBm, a Yagi adds alignment work, a fixed bearing and a longer cable without improving the household experience, because the donor signal is already healthy and the limit indoors comes from wall loss rather than capture. Reserve the Yagi decision for the survey numbers, not for the marketing photo.

Common Installation Faults and Fixes at 100 m2

Fault 1: A band LED stays dark after warm-up. Check the BS and MS labels first, then re-survey that band outdoors. A dark Band 20 light on an O2 customer usually means the donor 4G was never present at the omni position; moving to the side elevation that reads -105 dBm or better fixes it.

Fault 2: Flashing amber oscillation LED. Increase vertical separation, move the whip deeper inside, or reposition an intervening wall or ceiling. Do not attempt to lower output manually; the AGC already sits at the Ofcom-legal ceiling of >=10 dBm output and the only real fix is geometry.

Fault 3: One room stays at zero bars. Measure the distance and wall count from the whip. Beyond roughly 10 m through two solid walls, the 100 m2 rating is already exceeded; consider a second unit rather than re-aiming the omni, because the donor side was never the problem in that room.

Fault 4: Call audio muffled despite steady green LEDs. Look for the whip mounted inside a metal cupboard, behind a computer tower, inside a drawer, or behind foil-backed plasterboard; move it to an open shelf or plain internal wall with 30 cm of clear space in front.

Fault 5: 4G speed rises then drops a minute after testing. Classic oscillation loop. Power off, increase separation, and restart the three-minute AGC scan from a clean state rather than chasing the gain setting.

Fault 6: Connector corrosion on the outdoor plug. The weather boot was omitted or the connector faced upward. Reseat with fresh self-amalgamating tape and angle the plug downward so water drains away, particularly on an exposed cottage gable.

Fault 7: The 10 m included cable falls short of the bracket. Do not splice or stretch; order the measured 20, 30, 40 or 50 m continuous low-loss upgrade, because a joined run loses more signal than a single clean length.

Frequently Asked Questions