The 1W Label Is Not the First Choice: ES24TX Bays Explained
Quick Answer
Choose the bay before the wattage. The Happymodel ES24TX Pro Micro fits a five-pin Micro JR bay, while the Slim and Slim Pro use an eight-pin Lite bay. The non-Pro Slim tops out at 250mW; both Pro models are 1W-capable hardware, subject to radio power and UK RF limits.
The Bay Decides Before the Power Setting
These modules all provide 2.4GHz ExpressLRS, but their cases are not interchangeable. The Pro Micro measures 70 × 49 × 32.5mm, weighs 51g without its antenna and uses a standard five-pin JR socket. It is the obvious ES24TX choice when the transmitter has a full-size Micro JR bay.
The ES24TX Slim and ES24TX Slim Pro use the FrSky Lite-style eight-pin socket found on radios such as the X-Lite and on compatible expansion hardware for the Tango 2. The ordinary Slim is 60 × 30 × 20mm and 48g with its case and antenna. The Slim Pro is 67.5 × 30 × 20.5mm and 50g without its antenna.
Our catalogue exposes the naming trap neatly: the Pro Micro listing's opening copy calls it a “Slim Pro”, while its specification correctly says five-pin JR. Trust the socket, dimensions and exact firmware device—not a recycled introductory paragraph. Pro Micro versus Slim Pro is primarily a bay decision; Slim versus Slim Pro is the power decision inside the Lite-bay family. We would choose the native bay or compare the current RadioMaster Ranger module family, not buy an adaptor to force the wrong case onto a radio.
One Watt May Need More Than a Lua Setting
The non-Pro Slim is specified at 10-24dBm, or up to 250mW. Happymodel rates both Pro models at roughly 30dBm/1W, with cooling-fan provision. The Slim Pro carries the important qualification: a T-Lite or Tango 2 may need an external power solution to sustain the top setting. A menu option cannot make an under-powered module deliver stable RF output.
Do not treat 1W as the normal UK setting. Ofcom IR 2030 permits airborne wideband data systems at 2400-2483.5MHz up to 100mW e.i.r.p., with spectrum-access and power-density conditions. E.i.r.p. includes antenna gain, so the module's conducted-power menu is not the whole calculation. Use the correct current ExpressLRS regulatory domain and stay within the applicable limit.
The Firmware Target Trap
ExpressLRS currently separates these devices in Configurator. Select “HappyModel ES24 Pro 2.4GHz TX” for the Pro Micro, “HappyModel ES24 Slim Pro 2.4GHz TX” for the Slim Pro, and “HappyModel ES24 2.4GHz TX” for the non-Pro Slim. The two Pro names do not share one interchangeable device selection simply because both can produce 1W.
Before flashing, record the existing target, binding phrase and regulatory domain. Our ExpressLRS firmware update guide covers the safe sequence. For a fresh setup, set the radio's external module protocol to CRSF, confirm the module appears in the Lua script, then choose packet rate and legal power. Never power the module without its antenna fitted.
Our pick is simple: Pro Micro for a full JR bay, ordinary Slim when a Lite-bay radio only needs modest output, and Slim Pro only when the Lite bay and its power supply can support the extra headroom. Browse compatible hardware in our radio controllers and receivers collection, but match the bay before comparing headline power.
FAQ
Q: Can an ES24TX Slim fit a standard JR bay?
A: Not directly. Slim models use an eight-pin Lite-style bay; the Pro Micro uses the standard five-pin JR socket.
Q: Is the ES24TX Pro Micro compatible with 2.4GHz ELRS receivers?
A: Yes, provided transmitter and receiver use compatible ExpressLRS major versions, matching binding settings and the correct regulatory configuration.
Q: Should UK pilots select 1W?
A: No. The hardware rating is not permission to transmit at that level. UK compliance is based on e.i.r.p. and the conditions in Ofcom IR 2030.