Picking an ExpressLRS PWM receiver for rotorsignal fpv radios batteries often comes down to how many servos you need to drive and how much space and weight you can spare. Both of these RadioMaster options run on the 2.4GHz ExpressLRS system for long range and high reliability, but one is built for minimal, lightweight models and the other is built to handle a full fixed-wing setup.
Quick Verdict
If you fly small aircraft, boats, cars, or other lightweight models that only need four PWM outputs, the RadioMaster ER4 ExpressLRS (ELRS) 2.4GHz 4-Channel Receiver at $17.49 gives you the core ELRS performance in a compact, lower-cost package. If you need to drive up to eight servos on a fixed-wing, the RadioMaster ER8 ExpressLRS (ELRS) 2.4GHz 8 Channel Receiver at $40.99 is the purpose-built choice, with listed specs including a 4.5-8.4V power supply, 20cm high sensitivity antenna, and 16.5g weight.
At a Glance
| Model | Channels | Listed Price | Key Design Focus |
|---|---|---|---|
| RadioMaster ER4 ExpressLRS (ELRS) 2.4GHz 4-Channel Receiver [RM-HP0157.RX-ER4 | 4 PWM Channels | USD 17.49 | Compact design optimized for small aircraft, boats, cars |
| RadioMaster ER8 ExpressLRS (ELRS) 2.4GHz 8 Channel Receiver [RM-HP0157.RX-ER8 | 8-Channels | USD 40.99 | Fixed-wing use, support for eight servos |
Listed prices span from $17.49 to $40.99, a $23.50 spread between the two receivers.
Where Each Wins
RadioMaster ER4 wins for compact and simple builds
- 4 PWM channels keeps wiring and setup simple for models that don't need extra outputs
- Described as optimized for small aircraft, boats, cars, and other models requiring lightweight yet powerful functionality
- Lower listed price at $17.49 leaves more budget for other electronics
- Built on ExpressLRS with high-speed response and ultra-long-range capability
RadioMaster ER8 wins for fixed-wing and higher channel counts
- 8-Channels with support for eight servos, specifically noted for fixed-wing users
- Listed specifications detail power supply DC 4.5-8.4V, 20cm high sensitivity antenna, weight 0.58oz (16.5g), and size 1.69x1.18x0.59in (43x30x15mm)
- Includes ER8 2.4GHz ELRS PWM Receiver and voltage-related accessory per description
- Same ExpressLRS foundation for performance and reliability, but scaled for larger airframes
Product Notes
RadioMaster ER4 ExpressLRS (ELRS) 2.4GHz 4-Channel Receiver [RM-HP0157.RX-ER4
This receiver is positioned for lightweight models where every gram and every channel counts. The description highlights a compact design, optimized ground-up PCB design, and support for four simultaneous PWM channels, plus flexible configuration and high-speed response from the ExpressLRS system. At USD 17.49 it is the lower-priced option in this pair. A good reason to choose it is the combination of ELRS long-range performance with a minimal 4-channel footprint ideal for small aircraft, boats, and cars. A limitation is channel count - if your model needs more than four PWM outputs for flaps, retracts, or additional surfaces, this unit does not provide the extra outputs that the 8-channel alternative does.
RadioMaster ER8 ExpressLRS (ELRS) 2.4GHz 8 Channel Receiver [RM-HP0157.RX-ER8
Built with fixed-wing users in mind, this receiver supports eight servos and lists detailed hardware specs: DC 4.5-8.4V input, 20cm high sensitivity antenna, 16.5g weight, and 43x30x15mm dimensions. The description frames it as offering exceptional performance for models that need more control surfaces and auxiliary functions. At USD 40.99 it sits at the higher end of this comparison. Choose it when you need the full 8-channel PWM capability and the documented power and antenna setup for larger airframes. Its trade-off is size, weight, and cost - it is larger and heavier than a compact 4-channel unit and carries the higher listed price, which is more than needed for simple 4-channel builds.
Final Choice by Use Case
Choose the ER4 if you are building small, weight-sensitive models and four PWM channels cover your needs. You get ExpressLRS range and reliability without paying for unused outputs.
Choose the ER8 if you fly fixed-wing or any model requiring up to eight servos. The listed 8-channel support, 4.5-8.4V supply range, and included voltage accessory align directly with that use case.
Both share the RadioMaster ExpressLRS 2.4GHz platform and New condition, so the decision is not about system quality but about matching channel count, physical size, and listed price to your airframe.
