Review: Radiomaster ER5A/ER5C ExpressLRS PWM Receivers

by Oscar
Radiomaster Er5c Expresslrs Elrs Pwm Receivers Servo Pins Output Channels

Radiomaster released ER5A and ER5C PWM receivers, which allow you to plug your servos and ESC directly and take advantage of the high performance ExpressLRS in your planes, fixed wings, boats and RC cars.

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Learn about what ExpressLRS is in this article.

Where to Buy?

Available now at Radiomaster Store: 

I think they will soon be available here too:

No words about 900MHz version, currently only 2.4GHz available.

It comes with a manual and a longer antenna as a spare.

Radiomaster Er5a Er5c Expresslrs Elrs Pwm Receivers Unbox Accessories


  • Supports 4 proportional and 1 switch channel (ExpressLRS 2.x)
  • Supports 5 proportional channels (ExpressLRS 3.x)
  • Input voltage: DC 4.5-8.4V, supports HV Servos
  • T-shape antenna with UFL connector
  • ELRS 2.0 pre-installed
  • 5 output channels
  • Weight: ER5A 6.7 grams, ER5C 5.7g
  • Size: ER5A 37x19x13mm, ER5C 31x19x13mm

Closer Look at the ER5A/ER5C ELRS PWM Receiver

There are two versions: ER5A and ER5C. They are intended for different models.

  • C stands for cars (vertical pins)
  • A stands for aircraft (horizontal pins)

Radiomaster Er5a Er5c Expresslrs Elrs Pwm Receivers Compare

Both receivers have a robust injection molded plastic case. The only difference between the ER5A and ER5C receivers are just the case and servo pins direction. But because the ER5C uses less plastic, it’s about one gram lighter and also smaller in size. It really doesn’t matter which one to get, as long as it suits your application, they share the same software, hardware and range.

They have 6 standard servo connectors, support up to 5 PWM output channels.

Radiomaster Er5c Expresslrs Elrs Pwm Receivers Servo Pins Output Channels

Great for RC cars, fixed wing and RC boats. I hope Radiomaster would release another version with more output channels in the future, some aircraft requires at least 6 channels such as planes with retracts and flaps.

Radiomaster Er5a Er5c Expresslrs Elrs Pwm Receivers Fixed Wing

The ER5C and ER5A both use a T-style antenna and have U.FL connectors for easy replacement if you want to run a longer antenna.

Radiomaster Er5a Er5c Expresslrs Elrs Pwm Receivers Antenna Ufl Tear Down Pcb

How to Use


Radiomaster Er5a Er5c Expresslrs Elrs Pwm Receivers Manual

It’s basically like using a regular PWM receiver, you can power it from 5V, connect it directly to servos and ESC’s. They come with ExpressLRS 2.0 firmware, and ready to be flashed to 3.x over WiFi if you wish.

To bind, you can either flash the receiver with binding phrase (via WiFi), or just connect/disconnect power two times quickly, the 3rd time you power the receiver it will be in bind mode.

Note that there are more receiver options on the WiFi webpage, such as PWM output and failsafe settings. Simply put the receiver in WiFi mode via the ExpressLRS LUA script, or just power the receiver for 60 seconds without turning on the radio, it will enter WiFi mode automatically. Then on your computer, connect to ExpressLRS_RX WiFi network (password: expresslrs), and open browser, enter address

Radiomaster Er5a Er5c Expresslrs Elrs Pwm Receivers Wifi Flash Firmware Options Settings

As we know, Aux1 (channel 5) in ExpressLRS is always assigned to arming, which turns it into a 2-position output. If you don’t want that and want to use output 5 as a full resolution output, you can remap/assign channel 6 (Aux2) to output 5. You can configure which switch/slider/potentiometer you want to use for channel 6 in Mixes page in your radio.

The default 50Hz is good for ordinary servos, if you have digital servos you can set output to 333Hz here too.

How to Flash ER5C/ER5A

These RX come with ELRS V2.0 Maintenance Firmware. You can flash ExpressLRS firmware through WiFi.

Power on the RX, if there’s no binding after 60 seconds it will go into wifi mode.

Instruction on how to flash the receiver via WiFi.

  • Firmware category: DIY 2.4GHz
  • Device: DIY 2400 RX PWMP

Note that you cannot flash the ER5C and ER5A via Betaflight as it doesn’t use UART connection. If for any reason WiFi stops working, then the only option left to flash it is using BetaFPV’s ELRS Recovery Dongle.


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saints5354 2nd April 2024 - 10:04 am

Hi Oscar, may i know can i use the Radiomaster PWM receiver on Pixhawk 2.4.8 FC?

FrazeBigs 5th February 2023 - 10:26 pm

Anyone able to get RxBat telemetry data values to work? The telemetry link info (e.g. 1RSS etc) appears to work fine but I can’t figure out the telemetry data RxBat value. Is it supported by this Rx? If so any clues as to how EdgeTX Sensor Ratios/Offsets/etc need to be configured?

Oscar 6th February 2023 - 1:01 am

RxBt won’t work with this receiver because it’s using PWM signal (one way only) and it’s not getting any info about battery voltage.
If you need RxBt to work you need to use a flight controller with a receiver that uses UART connection.

FrazeBigs 7th February 2023 - 2:45 pm

Seems like a similar issue with most PWM RXs apart from the Matek judging by the following:

In theory it could do it if the PCB was designed with a voltage divider and routed to the right pin on the chip and the necessary code added. It’s weird that the RxBat has a value in it that does change but I’ve no idea what it’s measuring or based on.

Oscar 7th February 2023 - 3:51 pm

Well let’s hope it will come soon in the future!

Bob Neitzke 22nd January 2023 - 5:16 pm

Just received a Ranger Micro and ER5A rx from the RM preorder made last year. Arrivlal was mid Jan
Flashed 3.1.2 to Ranger Micro
Could not bind with original er5 so I flashed ER5a with 3.1.2
Now I cannot achieve a Double flash on the ER5 as I was previously able to do with original firmware.

Totally stumped !

Oscar 24th January 2023 - 1:58 am

did you flash the ER5A with a bind phrase? I believe if you did then it won’t go to bind mode (double flash LED)
Or did you can just enter a bind phrase in the web config page?

Wim 10th January 2023 - 9:21 pm

Thanks for the article but are you sure it’s a U-FL connector for the antenna?
I can’t find anywhere what type of connector it is and I have to connect another antenna. I can’t find any specs that confirm that it is U-FL, but it looks more like an ipex 4 connection to me….. All these connectors look the same……..

Thanks for the effort

Oscar 11th January 2023 - 11:23 am

IPEX 4 and UFL is the same thing

Wim 13th January 2023 - 1:10 pm

So you earn every day……. thanks!

Bob Neitzke 24th January 2023 - 5:57 pm

Today I discovered that there is a NEW ELRS version and after building and updating
everything works at expected so far.

I will use CH 2 and 4 for dual ailerons and Aux for the Rudder as it’s a bit less “granular”.

SO my next question is WHAT telemetry is being provided ?

Then how to set that up in mt TX16s?