Constructing a 5-inch HD freestyle quad with MEPS components involves a precise setup to ensure compatibility and optimal performance. Here's a detailed walkthrough:

Component Selection

Careful component pairing is crucial. The MEPS 2306 2450KV motors complement the Marmotte frame, ideal for 4S LIPO battery use. The MEPS 20x20mm stacked 45A ESC & F7 FC fit snugly within the Marmotte frame, while the Caddx Walksnail digital VTX offers high-quality video output, despite its incompatibility with the Marmotte frame (requiring 3D-printed mounts).

Preparation

Begin by creating a wiring diagram to plan connections, preventing soldering errors and ensuring Betaflight UART configuration. Utilize JST-SH connectors for easy ESC & VTX connections, reserving soldering for RX, GPS, and buzzer connections to the FC.

Assembly

Building starts with framing, motor installation, and strategic component placement. Optimal placement for the 20x20mm FC/ESC stack is crucial due to the frame constraints. Mount the MEPS Electronic Speed Control in the center, allowing motor cables to pass underneath, and secure it with grommets. Connect motor cables, keeping them tidy and protected within the frame.

VTX Mounting

The Avatar HD VTX's mounting challenge requires a tray mount to secure it at the frame's rear. Additionally, a 3D-printed battery/antenna holder can maintain antennas in a V-shaped configuration. Secure the VTX in the frame using the conversion mount and antenna/XT60 mount at the rear.

FC Installation

Utilize the MEPS flight controller, easily paired with the ESC and digital VTX. Make use of provided JST connectors, combining the ESC and Walksnail JST connectors, compatible with the FC's digital VTX input. Solder the RX before installing the FC onto the drone.

Final Configuration

Once components are connected, configure Betaflight settings, define motor directions, and assign RX modes. Configure VTX OSD layout and review Betaflight configuration, ensuring the necessary settings like CRSF protocol, GPS, PIN IO, OSD (HD), and VTX are enabled. Bench-test the drone to verify functionality, motor directions, and OSD output.

GPS Mounting and Final Checks 

Mount the GPS unit atop the battery, considering interference from the Avatar HD unit. Use a Vifly GPS Mate for pre-flight GPS lock and as a battery-powered buzzer for tracking purposes.

Building a compact 5-inch HD freestyle quad with MEPS components demands meticulous planning and precise execution to ensure seamless integration and optimal performance. Follow these steps to create a powerful yet portable drone capable of agile flights, perfect for mountain explorations with a GoPro payload.