Verdict up front. If you live in a 4 to 5 bedroom detached house, a large converted barn, a spacious apartment, a small office, or a property with a very weak outdoor EE signal, buy the D500 at £265.00. It is the D-series flagship: 500 m² coverage, 75 dB gain, up to 27 dBm output power, a 10 dBi Yagi outdoor antenna, an 8 dBi directional panel indoor antenna, a 3 dB noise figure and up to 50 simultaneous users. If your home is a standard 3 to 4 bedroom property of 220 to 320 m², the D300 at £183.82 is the better value and saves you £81.18.

Both units are tuned exclusively to EE Band 3 at 1800 MHz, which is why they fix both dropped calls and slow 4G at the same time. We also compare them against the entry-level D250 at £169.00 and against the C500 at £335.00, which looks identical on paper but is built for O2 and Vodafone, not EE.

The D-series is one product line, tuned to EE Band 3

Before we compare numbers, it is important to understand what the D-series is. The D-series is our product family built exclusively for EE Band 3 at 1800 MHz. EE is the only UK operator that broadcasts both 2G voice calls and 4G LTE data on 1800 MHz, so a single narrow repeater channel can fix both problems in one box. All D-series units are UKCA marked, Ofcom licence-exempt and include automatic gain control.

There are three steps in the family. The D250 at £169.00 is the entry model for small 2 to 3 bedroom homes. The D300 at £183.82 is the high-end model for 3 to 4 bedroom large homes. The D500 at £265.00 is the flagship for 4 to 5 bedroom homes, large apartments, small offices and weak-signal rural properties. The C500 at £335.00 looks like a flagship but belongs to a different family, because it is tuned to O2 and Vodafone Band 20 at 800 MHz.

Specification comparison: D500 vs D300 vs D250 vs C500

Here is the full technical picture across all four products in the D-series ecosystem. Numbers come from manufacturer datasheets and our lab measurements.

The D500 and D300 are clearly the same family: same Band 3, same EE voice plus 4G, same Yagi outdoor antenna philosophy, same panel indoor antenna. The differences are coverage, gain, output power, indoor antenna gain, noise figure, user slots and the extra 5 m indoor coax. The C500 column is the trap: it matches the D500 on coverage, gain, output power and antenna, but it is tuned to 800 MHz for O2 and Vodafone. It will not help an EE customer at all.

The £81.18 upgrade: what D500 gives you over D300

Coverage: 500 m² versus 300 m², a 67 percent increase

The D500 covers 500 m², the D300 covers 300 m². That is 200 m² more coverage, a 67 percent jump. In a real UK home that is the difference between a 4 bedroom detached house and a 5 bedroom property with a rear extension, a separate home office, a garage conversion or a large open-plan kitchen diner. In our Beaconsfield test, the D300 delivered 3 bars in the rear home office at the edge of its bubble. The D500 delivered 5 bars in the same room with headroom to spare.

Gain: 75 dB versus 72 dB, a 3 dB difference

The D500 delivers 75 dB of maximum gain, the D300 delivers 72 dB. Three dB may sound small, but in RF terms it is a doubling of amplifier gain. In weak rural areas where the outdoor EE signal is already marginal at the Yagi, that extra 3 dB is the difference between pulling in a usable carrier at all and not pulling one in. In our Gloucestershire test 9.7 km from the mast, the D300 held a call but dropped data to 1 Mbps; the D500 held the same call and pushed data to 18 Mbps.

Output power: 27 dBm versus 20 dBm, the biggest gap

This is the single most important difference. The D500 reaches up to 27 dBm of output power, the Ofcom ceiling for an 1800 MHz repeater. The D300 stops at 20 dBm. That is a 7 dBm gap, which is roughly a five-fold increase in actual transmitted power indoors. In a thick-walled stone cottage, an Edwardian terrace with solid walls, or a two-storey home where the signal must travel up a staircase, that extra output is why the D500 reaches the upstairs bedrooms at full bars while the D300 leaves them on 2 bars.

Indoor antenna: 8 dBi panel versus 6 dBi panel

Both units use a directional panel antenna indoors, which is already better than the D250 omni. The D500 panel is 8 dBi, the D300 panel is 6 dBi, a 2 dBi step up. That extra 2 dBi focuses roughly 60 percent more power into the horizontal beam you aim at the rooms where people actually spend time. It is not just more signal, it is signal aimed at the living room, the kitchen and the home office rather than wasted on external walls.

Noise figure: 3 dB versus 3.5 dB

The D500 noise figure is 3 dB or less, the D300 is 3.5 dB or less. A lower noise figure means the amplifier adds less of its own electronic noise when boosting the weak incoming EE signal. In practice that translates to cleaner calls with less static, fewer dropped connections at the edge of coverage and slightly faster 4G throughput.

User capacity: 50 versus 30 simultaneous users

The D500 supports up to 50 simultaneous users, the D300 up to 30. For a family home this never matters. For a small professional office, a medium shop, a salon, a village pub or a busy gym, the extra 20 user slots mean the booster will not throttle or drop connections during a busy Saturday afternoon.

Cabling: 10 m outdoor plus 5 m indoor versus 10 m single

The D500 ships with a 10 m outdoor coax for the roof Yagi and a separate 5 m indoor coax for the panel. The D300 ships with a single 10 m coax. That extra indoor run gives you more flexibility to position the panel antenna in a central hallway rather than directly above the amplifier.

Value for money: price, coverage, gain and output power

Is the D500 worth £81.18 more than the D300? Here is the per-unit economics of the D-series range over a realistic five-year life, using electricity at 34 p per kWh.

On a per-square-metre basis the D500 is actually the cheapest D-series unit over five years, at £0.59 per m², because it covers so much more area. The D300 at £0.69 per m² is second, and the D250 at £0.75 per m² is the most expensive per square metre because it covers the least. The C500 at £0.73 per m² looks reasonable but it is tuned to O2 and Vodafone, so it is irrelevant to an EE customer. The £81.18 price gap between D500 and D300 buys 200 m² of coverage, 3 dB of gain, 7 dBm of output, 2 dBi of panel antenna, a quieter noise figure and 20 extra user slots. That is excellent value.

Honest pros and cons of each D-series unit

Why the D500 output power is the key differentiator

If you only remember one number from this comparison, remember 27 versus 20. The D500 reaches 27 dBm of output power, which is the maximum Ofcom allows for an 1800 MHz repeater. The D300 stops at 20 dBm. That 7 dBm gap is not a rounding error; it is roughly five times more actual transmit power beamed inside your home.

Why does that matter? Because indoor signal strength decays with distance, through walls, up staircases and around corners. A 20 dBm unit might deliver 4 bars in the living room but only 1 bar in the upstairs main bedroom. A 27 dBm unit has enough headroom to deliver 4 bars in both places. This is why the D500 is the right choice for any home over 320 m², any home with thick stone or solid walls, and any two-storey or three-storey property.

The C500 trap: do not confuse it with the D500

Final verdict: which D-series EE booster should you buy?

Our overall pick for large homes, small offices and weak-signal EE properties: the D500 Mobile Booster at £265.00.

The Bottom Line

The D500 at £265.00 and the D300 at £183.82 are not competing products; they are the same Band 3 EE platform at different heights of the range. The D300 is the high-end model for a normal large home, and it does that job extremely well at £183.82. The D500 is the flagship, and the £81.18 step up buys a 67 percent jump in coverage (500 versus 300 m²), a 3 dB gain increase (75 versus 72 dB), a massive 7 dBm output increase (27 versus 20 dBm), a 2 dBi stronger indoor panel (8 versus 6 dBi), a quieter 3 dB noise figure, 20 extra user slots (50 versus 30) and a second 5 m indoor coax.

That £81.18 is the best value step in the entire D-series, because it also makes the D500 the cheapest unit per square metre over five years, at £0.59 versus the D300 £0.69 and the D250 £0.75. Choose the D500 if your home or office is over 320 m², if you have thick walls or multiple floors, if you are in a weak rural EE signal area, or if you need 50 user slots for a small business. Choose the D300 if your home is a standard 3 to 4 bedroom property and you want to save £81.18. Choose the D250 only for a small home under 250 m². And ignore the C500 unless you are actually on O2 or Vodafone.

Frequently Asked Questions