BETAFPV A03 400mW 5.8G VTX

BETAFPV A03 400mW 5.8G VTX

A03 400mW 5.8G VTX, a video transmitter with OpenVTx firmware, supports both the SmartAudio and Tramp protocols. It features PIT/RCE/25mW/100mW/400mW adjustable output power for different use. With the 26*26mm mounting hole size, it is suitable for whoop or toothpick drones like X-Knight seriesBeta85X/95X seriesTWIG series and Pavo series.

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Know More About OpenVTx

Big thanks to Jye Smith and all contributors for their time and energies to OpenVTx project.

OpenVTx refers to open source video transmitter firmware for the FPV community, which aims to provide firmware with both the SmartAudio and Tramp protocols. Either protocol can be used on the flight controller and on VTx power up the protocol used is automatically detected by OpenVTx. For more information, you can know it from OpenVTx GitHub.

Bullet Point

  • An open-source video transmitter with OpenVTx firmware. The A03 VTX supports SmartAudio and Tramp protocols. Through these protocols, the flight controller is able to adjust the video transmitter settings, which are the power, the band, and the channel of the transmission.
  • A03 VTX is a high-quality 5.8GHz VTX with strong anti-interference ability and stable transmission. Comes with PIT/RCE/25mW/100mW/400mW adjustable output power, allowing the perfect amount of output power to be selected based on your FPV needs.
  • Overall weighing 4.9g with a small-size layout, A03 VTX comes with a 26*26mm mounting hole and is perfectly suitable for whoop or toothpick drones like the X-Knight seriesBeta85X/95X seriesTWIG series, and Pavo series drones. 
  • Featuring a fixed mounting hole and 6-pin connector, less solder work needed, which makes it’s super easy to install.


  • Item: A03 5.8G VTX
  • Output power: PIT/RCE/25mW/100mW/400mW (10-26dBm)
  • Supply voltage range: 7-35V
  • Current (8v): <300mA (400mW)
  • Weight: 4.9g (excluding antenna)
  • VTX size: 30.34*30.34*4.6mm
  • Mounting Hole Size: 26*26mm
  • Antenna: Air Antenna (MMCX Straight)
  • Frequency: 5.8GHz 48 channels
  • Raceband: 5658~5917MHz
  • Channel SEL: SmartAudioV2.0 & Tramp
  • Modulation type: FM
  • Antenna port: 50 Ω
  • Operating temperature: -10℃~+60℃
  • Recommend drones: 26*26mm mounting hole, Pavo seriesX-Knight seriesBeta85X/95X series, and TWIG series

Comparison to BETAFPV VTX Series

One of the best VTX on BETAFPV VTX Series. A03 400mW 5.8G VTX is a video transmitter with OpenVTx firmware and supports both the SmartAudio and Tramp protocols. Besides, A03 VTX sports a better cost performance and comes with OpenVTx firmware, which supports adjustable output power and frequency, in contrast to A02 VTX. In a word, A03 VTX works perfectly without any reduction in performance or power.

Mounting Hole 26*26mm 26*26mm or 14*18mm 14*18mm 26*26mm
Max Output Power 400mW 350mW 350mW 800mW
Supply Voltage Power 7-35V 4.5-5.5V 4.5-5.5V 7-35V
Protocol SA&Tramp SmartAudio
Firmware OpenVTx BETAFPV VTX System
Compatible Drones Whoop & Toothpick Drones 3-5 inch Drones 65-85mm Whoop Drones Whoop & Toothpick Drones

Diagram for A03 VTX

Below is the diagram picture for A03 400mW 5.8G VTX.

Below is the instruction diagram for connecting the VTX with Toothpick F722 2-6S AIO Brushless Flight Controller 35A(BLHei_32). The line color in the diagram matches the 6-pin connector wires' color.

Band & Channel & Power Settings for A03

The band, channel and power for A03 400mW 5.8G VTX can be changed by the OSD menu only. Enter the OSD menu by radio transmitter sticks ( Pitch Stick UP and Yaw Stick Left), then select FEATURES -> VTX SA to change the frequency and power.

LED status is shown below. VTX mode (band/channel/power) LED indication is similar to TBS's approach.

Below is the frequency table for A03 400mW 5.8G VTX.

Betaflight CLI for SmartAudio or Tramp protocols can be obtained from here:

Active and Exit the PitMode

Set PIT ON or OFF on OSD menu.

Active and Exit the RACE Mode

When at a race event and using pitmode on a switch with Betaflight, select the RCE VTx power level. It will force pitmode on boot and only use 25mW. Select POWER and set RCE mode on OSD menu.


  • 1 * BETAFPV A03 5.8G VTX
  • 1 * 6-Pin FC Cable
  • 1 * Air Antenna(MMCX Straight)
  • 3 * Anti-Vibration Rubber Dampers