Installing a new VTX in the Emax Hawk 5

Sneak peak of the finished product

The Emax Hawk 5 is arguably the best bind and fly quadcopter going as I found in my initial review but can also be greatly improved with a few budget modifications as I wrote about in my blog on bang for buck improvements. I do however see a number of people complain about the stock Emax Hawk 5 vtx however mine has been functioning well. That being said, you cannot adjust setting in betaflight OSD via smart audio or tramp telemetry which is a let down on a 2018 quad. In the interest of sharing I've removed the stock VTX and replaced with one of the larger VTXs currently available (the AKK Infinite VTX/DVR) to prove it can be done.

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The VTX I chose for this project is the AKK Infinite which incorportates a DVR into the VTX

The VTX
The VTX I chose is the AKK Infinity DVR VTX. This is very similar to the HGLRC VTX/DVR that was reviewed here. As the name suggests this is a smart audio VTX in 30.5mm VTX with a built in DVR. I chose those for 2 reasons: First it's big. If I can fit this in you can fit anything! Secondly I like the DVR for recording breakup-free footage. For me I like the nimbleness of the Hawk 5 and don't want to weigh it down with a HD Cam. Other key features of the VTX/DVR:

• DVR Recording in 640x480 (VGA)
• Output power: 25mW/200mW/600mW/1000mW
• SmartAudio/VTX Telemetry (configurable through BetaFlight OSD)
• Input voltage: 7V-26V (i.e. 2s - 6s)
• MMCX Antenna connector

The AKK Infinite DVR/VTX can be purchased directly from AKK here: https://www.akktek.com/products/vtx/akk-infinite-dvr-vtx.html

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Other parts
Just quickly I used the following tools and parts in the instructions below:

• ​Daniu Side Cutters
• TS100 soldering iron
• Heat shrink in a pack
• m3 standoffs

The install
Please note all the pictures below relate to the install of the AKK Infinite but install should be identical or at least nearly the same for others. I had to remove the buzzer and relocate the receiver for this VTX but depending on the size of the VTX you install you may need to do only one or neither. Follow picture left to right then down. All pictures will enlarge if you click on them.

1. Remove the Hawk 5 top plate (4 x m2 screws)

2. Screwdriver is pointing at the double sided foam tape that helps hold the vtx to the FC

3. More of the foam tape

4. Use side cutters (these ones) to snip the 3 pins that connect the VTX to the FC.

5. Once pins are snipped carefully remove vtx which is still stuck to VtX using sticky foam tape

6. Next snip the pins holding the XM+ receiver to the FC 

7. Here is what it looks like immediately after receiver pin cut

8. FC is now fully exposed

9. Remove FC and flip over to use soldering iron to heat and push out pin remnants

10. Remove old VTX pins here. I used the TS100 which is an excellent soldering iron

11. Remove old receiver pins here

12. I had to remove the buzzer too since it would foul on my full size DVR/VTX at bottom mid-right

13. Solder signal, + and - wires to receiver in order above. I just used some spare yellow, red and black wire I had. I then heat shrinked since this was due to go between FC and ESC boards. Heat shrink in a pack here

​14. Heat shrinked and re-wired receiver

15. Receiver wired underneath FC- note wiring colurs and connections

16. The FC connects to the ESC by pins. MAKE SURE THESE ALIGN when reinstalling FC

17. FC resinstalled with recevier sandwiched between FC and ESC. You need extra m3 standoffs available here

18. Stock wires removed from new VTX

19. New wires installed on underside of VTX pointing inwards for cleanest wiring. Note only VTX power supply, video in and smart audio connected since camera powered by FC

20. AKK Infinite DVR/VTX now wired in. NOTE: UPDATED TO USE BATTERY VOLTAGE HERE 

21. New VTX now in place

22. Here you can see there is suitable clearance and access to DVR microSD slot 

23. Nylon nuts in place and minor mod to my VTX antenna mount to fit 90deg MMCX connector

24. All back together!

What did I learnt from the install?
Firstly I can appreciate how Emax has made the most of the space with compact components. If I were to do this again I'd consider a smaller vtx to see if I could get away with removing less components, possibly an AKK FX2 ultimate mini half board or even an AKK nano 2, nano 3 or Oscar's backpack which may allow you to keep the buzzer AND receiver in place. That being said I'm really pleased I installed the DVR unit for extra functionality and did manage to retain a proper SMA antenna mount.

Set up and flight performance
I'm pleased to say that on the very first power up it functioned as expected. All Ineeded to do was to allow smart audio as a peripheral funtion on UART 6 in betaflight and smartaudio (VTX channel and power control through OSD) was fully funtional.

For video signal performance please see below for goggle DVR recording comparing the stock VTX on 25mW and 100mW compared to the AKK Infinite VTX running 25mW, 200mW, 600mW, 1000mW. A quick spoiler: 1000mW was unstable. This is likely because of the load the VTX and DVR units place on the 5v flight controller BEC (which also supplies the camera). 2 solutions here - run at 600mW or below or power the VTX from the VCC pad (picture below) instead of the 5V supply used by the stock VTX. This gives the VTX full access to battery power which is fine since it is rated up to 26v. For me I'll run 200mW maximum since I don't like to overload BEC circuits since it can make weird things happen - FC brown out, flickering OSD etc.

Update December 2018: I now recommend using vbat/vcc to power the vtx as covered here.
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Overall for me video performance was comparable. The AKK VTX does however offer greatly improved functionality:

• DVR capture without signal loss
• Smart Audio (full VTX control through betaflight OSD)
• Much higher options for transmit power

In Conclusion...
I'd definitely recommend changing the VTX for a different unit that supports Smart Audio if your VTX is not working as well as you'd like, but as you can see above it does take some planning and work. Even if it is working well some of the extra features that can be had on more modern VTXs may be worth the jump especially if you are confident with this type of work. Even if you aren't confident this guide should hopefully help you. AKK tend to make a good budget VTX with a lot of features but you can subsitute your favourite model here easily enough.

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This was last pack of the day and I'm pleased to say Hawk5: 1, Tree: 0