The Walkera Devo 7e is a good compact transmitter. Install the Deviation firmware, and you have an unbeatable transmitter that supports many protocols. The one wishlist item that owners have is that the TX can be use for longer range flying. Fortunately, the gurus hacking on the Devo 7e found that by shorting a single diode, you bypass the intentional handicapping of the radio transmission, and increase the power output by 10x. Making it on par with it’s full range siblings, the Devo 10 and Devo 8s.
All it takes is to remove the metal shield to access the diode that needs to be bypassed.
There’s a large amount of solder so the risk for solder splashes is high. Therefore, eye protection is important.
I start by putting on eye protection. Then add some additional solder to each of the two corners you’re going to remove first. The additional solder helps the solder blob stay heated and molten. Then quickly, move your solder iron back and forth between two points. Use a hobby knife or tweezers to lift one side of the shield. Then simply repeat for the second pair of solder joints and the shield will come off quite easily.
Then it’s just a matter of identifying the diode and shorting it. Before doing so, it’s a good idea to do a range test to get a reference of how far the stock radio transmission is able reach. Important for testing whether your mod was successful at the end.
The safest way we have found to accomplish this is to use a conductive ink or compound. Such as the stuff used to repair the defogging lines on a automobile rear window. These can be found for about $8-11 at most automotive parts store. With the conductive ink, you can just paint diode and make sure it’s covered well enough so both ends of the diode is now electrically connected.
I have seen circuit writer pens with conductive ink. Generally pricey at $20. You press the tip in to release the ink. However, do not press inward over the circuit board. A flood of ink may pour out. So press over a piece of scrap plastic to see how much flows out or create a drop. Then just transfer and short the diode. Build it up to ensure you have good coverage.
Now, for those who intend on soldering because it’s what they already have on the bench and do not want to buy conductive ink…please take note to help mitigate accidents and increase your chances of being successful.
Note: the area is very cramp with surrounding SMD. I suggest you use tape, such as Kapton, or liquid electrical tape, or something that will help mitigate unintentionally removing of a surrounding SMD.
There are several methods to short the pads the diode is soldered to. Nowadays, the community feel it’s best to steer people towards the use of conductive ink. (See the updated section above.) It’s easier to get right and not risk accidentally and unintentionally desoldering the surrounding smd components.
Alternatively, you can simply solder a thin wire on each end of the diode. This way, you can reverse the changes. This is how I am modding Devo 7e nowadays:
And here’s a photo of how I first did the mod. I’ll include it for historical purpose. Hidden by default so it doesn’t clutter this post and confuse newbies with too many optional ways to accomplish the mod.
[toggle title=”Click to show original method”]
I originally accomplish the mod by using solder to bridge the two points after I removed the diode that was there. I used a small wire to help the solder flow and bridge the two points. See image below.
Once you are done bridging the two points, test the radio and ensure you are still able to bind to and control the R/C. Once you deem the mod has been successful, it’s important to put back on the RF shield.
I do this by cleaning up any solder so the shield can sit flat. Then it’s just a matter of adding new solder so everything looks the way it did before you removed the shield.
Lastly, make sure you edit your
tx.ini file and enable the additional power.
The latest Deviation firmware have moved the [modules] section from the tx.ini to a hardware.ini file. So locate and edit the [modules] section in the appropriate file depending on which version of Deviation you are using.
(Tip in layman’s term: A semicolon preceding the line means that line has been “commented out,” therefore it’s not read. Remove the semicolon to “activate” the line)
has_pa-cyrf6936 = 1
Finally, do another range test to ensure your mod is successful before you close everything up.
Here’s a thread discussing the mod with some graphs of the increase in power output.