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Apex 5" HD on base frame kit

A digital HD build on the Apex Base Frame Kit

🇬🇧 For my first DIY build ever I wanted a strong 5" frame.

I chose the ImpulseRC Apex Base Frame Kit because I did not want to rely on a HD specific frame and loose the space made for the DJI Air Unit.

It was quite a challenge to get everything to fit properly but I love the result and I hope you'll appreciate the density and great balance of this build.

This ends up as a compact (but not too much) build without sacrifying the space for the electronics. It is clean (to my standards at least) and very powerful.

I enjoyed working on it very much and I hope you'll get a sense of it reading this build guide. Enjoy!

Apex HD on Base Kit overview

Hardware list


Those links are NOT affiliate links. I just share the links where I actually bought the stuff needed for this build.

Notes to self for future improvements

Build steps

Frame assembly

Follow the official ImpulseRC Apex guide to assemble the frame.

Apex Base Kit

Caddx Vista on the 20x20 rear mounting holes


You will need 4 long M2 screws that are not provided with the kit. Nuts are the ones provided with the kit.

Apex Base Kit 20x20 Caddx Vista screws

Apex Base Kit 20x20 Caddx Vista mounted

The 20cm cable for Caddx Vista is better protected than the standard one.

Apex Base Kit 20x20 Caddx Vista cable

Caddx Vista VTX antenna mounting

Use the U.FL TBS Unify Pro/HV SMA cable with the provided Apex clamp and fix it to the rear for the antenna.

Apex Base Kit 20x20 Caddx Vista antenna mount

Apex Base Kit 20x20 Caddx Vista antenna mount back

ESC and XT60 mounting

Do not fear to cut short the XT60 leads: its TPU support will strain releave the cable on the standoff.

Apex Base Kit XT60 cable cut


Be mindful of the fact that the ESC mounted in reverse positionto leverage the space at the front for the capacitor. You will need to reallocate the motor resources on the CLI (see the betaflight section below).

Apex Base Kit ESC mount view

Apex Base Kit ESC mount view side

Apex Base Kit ESC mount view top

RX wiring

Nothing surprising here, wiring the TBS Tracer Nano RX is straightforward!

Apex Base Kit TBS Tracer RX wiring

Apex Base Kit FC mount view

FC mounting

Use the longest of the provided FC-to-ESC cables (it connects perfectly, mind the wire direction) and connect the Caddx Vista.

Apex Base Kit FC mount view

Apex Base Kit FC mount view focus

RX placement

Once protected, the RX is stuck on top of the Caddx Vista using double sided tape.

Apex Base Kit RX mount view

The Tracer Immortal T antennas fit well: one is zip tied in the lower plate by the provided clamp and the other is passing through the remaining hole in the upper VTX clamp.

Apex Base Kit RX mount view back

Apex Base Kit RX mount view fixed

Finishing the build

Finish the build by placing the top plate and the plastic provided covers on the arms.

Apex Base Kit RX mount view fixed

Betaflight configuration

  • Betaflight target: TMTR/TMOTORF7(STM32F7X2)


Apex Build Betaflight ports

Bi-directional DShot is enabled and supported natively by the BLHeli32 ESC:

Apex Build Betaflight config

Filter settings to accomodate the bi-directional DShot:

Apex Build Betaflight filter config


Apex Build Betaflight modes

Joshua Bardwell's OSD for DJI FPV Google settings:

Apex Build Betaflight OSD

Motor resource reallocation

Since the ESC is mounted in reverse position, the motors need to be reassigned on the CLI. Depending on your wiring, IDs may change.

# resources
resource MOTOR 1 B01
resource MOTOR 2 B00
resource MOTOR 3 C07
resource MOTOR 4 C06

Minimal CLI diff

This is the minimal CLI diff that I set up without advanced tuning. It flies very well but as I will tune it better I will add a section to this build guide.

# Building AutoComplete Cache ... Done!
# diff all

# version
# Betaflight / STM32F7X2 (S7X2) 4.2.6 Jan  5 2021 / 19:08:42 (a4b6db1e7) MSP API: 1.43
# config: manufacturer_id: TMTR, board_name: TMOTORF7, version: e02dd6f2, date: 2020-11-04T11:31:26Z

# start the command batch
batch start

# reset configuration to default settings
defaults nosave

board_name TMOTORF7
manufacturer_id TMTR
mcu_id 002f00263338510639393832

# resources
resource MOTOR 1 B01
resource MOTOR 2 B00
resource MOTOR 3 C07
resource MOTOR 4 C06

# feature
feature RX_SERIAL

# beacon
beacon RX_LOST
beacon RX_SET

# serial
serial 1 1 115200 57600 0 115200
serial 4 64 115200 57600 0 115200

# aux
aux 0 0 0 1800 2100 0 0
aux 1 1 2 1300 1700 0 0
aux 2 13 1 1300 2100 0 0
aux 3 35 2 1800 2100 0 0

# rxfail
rxfail 7 s 750

# master
set gyro_lowpass2_hz = 375
set dyn_notch_width_percent = 0
set dyn_notch_q = 250
set dyn_notch_min_hz = 90
set dyn_notch_max_hz = 350
set dyn_lpf_gyro_min_hz = 300
set dyn_lpf_gyro_max_hz = 750
set acc_calibration = 26,3,238,1
set min_check = 1000
set rssi_channel = 8
set serialrx_provider = CRSF
set dshot_bidir = ON
set motor_pwm_protocol = DSHOT600
set small_angle = 180
set osd_warn_rssi = ON
set osd_rssi_alarm = 40
set osd_vbat_pos = 257
set osd_rssi_pos = 2486
set osd_rssi_dbm_pos = 161
set osd_tim_1_pos = 353
set osd_tim_2_pos = 321
set osd_flymode_pos = 2241
set osd_throttle_pos = 313
set osd_vtx_channel_pos = 193
set osd_craft_name_pos = 33
set osd_gps_speed_pos = 161
set osd_gps_lon_pos = 33
set osd_gps_lat_pos = 1
set osd_gps_sats_pos = 65
set osd_home_dir_pos = 2275
set osd_home_dist_pos = 2145
set osd_flight_dist_pos = 184
set osd_altitude_pos = 2177
set osd_warnings_pos = 2441
set osd_avg_cell_voltage_pos = 2516
set osd_disarmed_pos = 2411
set osd_flip_arrow_pos = 65
set osd_core_temp_pos = 248
set osd_log_status_pos = 97
set osd_gps_sats_show_hdop = OFF

profile 0

# profile 0
set dyn_lpf_dterm_min_hz = 105
set dyn_lpf_dterm_max_hz = 255
set dterm_lowpass2_hz = 225
set d_pitch = 32
set d_roll = 30
set d_min_roll = 0
set d_min_pitch = 0

profile 1

profile 2

# restore original profile selection
profile 0

rateprofile 0

rateprofile 1

rateprofile 2

rateprofile 3

rateprofile 4

rateprofile 5

# restore original rateprofile selection
rateprofile 2

# save configuration