The 0.02g Difference That Changes Where Your ELRS Antenna Lives
Quick Answer
Choose the Happymodel EP2 when a whoop needs the smallest self-contained installation. Choose the EP1 when you can route an external antenna away from carbon and electronics. We would buy the TCXO version of either today; for larger or long-range builds, step up to the EP1 Dual rather than pretending antenna convenience equals link resilience.
The 0.02g Comparison Is a Trap
Our current catalogue lists the standard Happymodel EP1 at 0.42g without its antenna and the Happymodel EP2 at 0.44g with its ceramic antenna. That apparent 0.02g gap is not a useful buying criterion because the measurements do not include the same hardware.
The real choice is antenna placement. EP1 has a U.FL/IPEX-connected dipole, so its active elements can sit clear of the flight-controller stack and carbon. EP2 carries its ceramic antenna on the 10 × 10mm board, removing a cable and connector but forcing the antenna to live wherever the receiver fits. ExpressLRS warns that burying a ceramic-antenna receiver behind carbon reduces performance.
| Receiver | Antenna | Listed size | Listed weight | Our pick for |
|---|---|---|---|---|
| EP1 | External dipole | 10 × 10 × 3mm | 0.42g without antenna | Toothpicks and open frames |
| EP2 | On-board ceramic | 10 × 10 × 6mm | 0.44g | Tight, short-range whoops |
| EP1 Dual TCXO | Two external dipoles | 19 × 14mm PCB | 1g without antennas | Larger and range-focused aircraft |
TCXO or Standard?
The EP1 TCXO adds a temperature-compensated crystal oscillator. Happymodel describes this as keeping clock frequency accurate as temperature changes; it does not turn a single-antenna receiver into diversity hardware. Both EP1 and EP2 still use one SX1280/SX1281 RF path and support receive rates from 25Hz to 500Hz.
For a new installation, our answer is simple: choose TCXO when available. Choose the EP1 Dual TCXO only when the 19 × 14mm board and two antennas fit. Its dual SX1280/SX1281 RF chains are the meaningful reliability upgrade; mount the antennas in different orientations rather than parallel.
Wire EP1 and EP2 the Same Way
Use a free, uninverted full UART: receiver TX goes to the flight controller's RX pad, receiver RX goes to the matching TX pad, plus ground and regulated 5V. The crossed TX/RX labels are intentional. In Betaflight, enable Serial RX on that UART and select CRSF as the receiver protocol.
If the receiver shows a solid LED while the transmitter is off, ExpressLRS documents that some flight-controller RX pads can pull low and put an ESP receiver into bootloader mode. Move it to another UART before blaming firmware. Use the current Happymodel EP1/EP2 target for the single receivers and the separate EP Dual target for the diversity board. Our ELRS binding walkthrough covers binding phrases and flashing; the broader receiver selection article explains when another receiver family is a better fit. You can also browse our radio receivers.
FAQ
Q: Is the EP2 better because its listed antenna gain is higher?
A: No. Happymodel lists 3.7dB for the EP2 ceramic antenna and 2.23dB for the EP1 dipole, but installation dominates. A ceramic antenna buried beside carbon can perform worse than an externally routed dipole.
Q: Can EP1 and EP2 use the same firmware target?
A: Yes. Current ExpressLRS documentation groups EP1 and EP2 under the same Happymodel 2.4GHz receiver target. EP Dual uses its own target.
Q: Which one would we put in a 65mm whoop?
A: EP2, provided its ceramic antenna can face clear air. On a toothpick, 5-inch quad or fixed wing with routing space, we would use EP1 TCXO; for higher-consequence range work, we would use a true-diversity receiver.