About: Wile E. Coyote, passionate DIYer, wasn't as unlucky as you might think. If you try you will understand my statement: some of its contraption WERE ACTUALLY WORKING, at least at the beginning. It usually didn't …

Hi Folks,

my career in the rc hobby started some years ago with a 40+ year old 3-channel TX/RX kit, found covered in dust in a basement, but it's more correct to say that it started BECAUSE OF this kit.

Actually, the first transmitter that kept something in the air (for more than three seconds, at least) was the cheap, basic, yet widespread Flysky FS-I6.

I have to say that in stock configuration it has a very low appealing, with its few built in functions and its cheap construction. Nevertheless it's one of the cheapest unit among the programmable transmitter, so it's somehow balanced in the price/performance ratio.

The most interesting feature of this receiver is that -thanks to its diffusion- A LOT of people studied how to improve its features. And they did an amazing job!

In stock configuration it's a 6 channels (ch) basic transmitter (TX), without any kind of feedback from the receiver, with basic ergonomy and basic software. The stock transmission range actually isn't that bad, more than 1Km when paired with an FS-X6B or an FS-IA6B, maybe 2Km in the best condition. But range is a strange thing: the more you have the more you would like to have.

My modded TX now is a 14ch transmitter, with some useful feedback like battery voltage and RSSI, a better ergonomy, more physical switches and a feature rich firmware. The range is also improved, i can't tell you a specific distance limit After a certain distance the link's quality depends on several specific optimizations (how far is the receiver antenna from the esc? huge variable in the range equation...).

How much does this overhaul costs (from china, of course)? Well, assuming you already have a 3D printer, way less than 10€! Happy Days!

Now, after the mod, the main criticism is about would be the gimbals quality. They aren't high quality gimbals, nobody can claim that. On the other hand they aren't that bad at all, i'm still using the original ones. I know that i could replace them with higher quality ones, but imho it's not worth the expense (unless you have to replace them anyway, then maybe).

Step 1: Tools and Components

These mods are really easy to perform and they are pretty much independent, so you can choose to follow only some steps. I obviously recommend to do all the suggested mod.

Basically you are required to do these task in the following steps:

  1. Better ergonomy: 3D print some files, maybe paint them with acrylic spray paint.
  2. Better range: drill two 6mm holes in the transmitter plastic.
  3. Additional features and (way) more channels: flash a new firmware, it's up to you to choose to use a specific USB dongle or to use a common (hopefully FDTI) serial adapter.
  4. Better switches: drill another hole and solder few wires in really easy places. A multimeter could be helpful.

To summarize, for this project you need basic soldering tools and few other basic DIY-electronic tools, I've collected my usual tools on this page.

The required components are really cheap, the most difficult task would be to buy a single item instead of a batch. I could actually easily reclaim everything from broken electronics!

I've collected every required component here and, depending on the mod you want to do, you'll need:

  1. Better ergonomy: a 3D printer, if you don't already have one, or ask someone to print something to you. Acrilyc spray paint is suggested.
  2. Better range: two pigtail cables, approximately 15cm, i-pex connector on one side, rp-sma on the other one. You also need two antennas, you can use antennas from broken routers as long as they were only 2.4GHz routers.
  3. Additional features and (way) more channels: there's a flysky-specific usb/serial converter that makes the flashing process trivial, i use it because it's really comfortable to use and there's no risk to screw everything up with a wiring mistake. Long time ago i tried the first modded firmwares using a generic FTDI usb-serial adapter. It also works, you only have to plug some more wires and have more care.
  4. Better switches: any three way toggle switch (on-off-on) can do the job, really. In the linked component pages i've listed several switch type, you only need one and you can choose whichever you want. I choose a rubber sealed one, it really doesn't mean anything because the TX is not waterproof, i just liked it. Beside the switch you need some small cable and few resistors (220R, 4K7, 10K). Long time ago purchased a resistor kit for a bunch of €, and it provided any resistor i had to use so far. It's a nonsense to buy a single resistor. You can use any small wire you have at hand. On the component page i listed the best wire for this kind of job, just in case you want it, but it isn't mandatory at all.

Step 2: Better Ergonomy

That's easy, just 3D print something.

Here you can find in a single place all the file i've tested and kept mounted on my transmitter. There are several other parts on that site, just search for FS-I6 and you'll find dozens files specifically designed for our transmitter. For some parts some sanding might be required, depending on your printer's calibration.

For expert 3D printers: that's all you need, skip and go to the next step.

I guess most of you already have a 3D printer and a preferred filament, but someone might doesn't know some details. I used a modded CR-10 and simple PLA, you can use whatever printer you like and any kind of filament. Nevertheless i strongly recommend PLA, is the easiest filament to use and it has other interesting properties.

In fact, PLA is not only easy to print, but it also has better dimension tolerances than -for instance- ABS. If you fear that PLA won't endure outdoor for a long time, because someone told you that's biodegradable don't worry, it won't.

It won't, especially if you also paint the parts with acrylic paint like i did. No, seriously, the enviroinmental conditions that can degrade the PLA are quite rare in nature, it won't melt in your hand if it rains.

The reason, if you really want to know it, is that Proteinase K (which catalyzes the hydrolytic degradation of PLA) can't be found everywhere.

Is the sunlight an issue? No, except for possible excessive heat. It would only fade the color, but it won't affect the strength (like most of the plastic out there). But, hey, we also painted the parts, so who cares?

Ps: spray paint a 3D printed object it's a good trick to have a better surface smoothness.

Step 3: Better Range

In order to improve the range we can't increase the transmitting power, but we can modify the "signal shape".

One of the more common misconception is that an high gain antenna is "more powerful", it isn't. Actually, if the high gain antenna had used more watts, it would have required more watts from the signal generator, and this additional power could easily generate a thermal issue. The high gain antenna only concentrate the signal's power in a specific zone, "stealing some range" from other directions.

With this mod the transmitter, paired with a good receiver, could at least be considered a "medium range" transmitter. No, you won't outrange the TBS Crossfire or the R9M, but still...

Please note that now your transmitter is more directional. It's not like having a 1m-long yagi directional antenna, but try to maintain the antennas PERPENDICULAR respect to the vehicle's direction. Pretend that your hand is a gun, the index is pointing at the vehicle, the thumb is at 90° and it's the antenna's optimal orientation.

It's obvious for the experts but maybe it's not really intuitive for the noobs: the direction which a dipole antenna is "pointing", the thumb, is the least efficent one, so in that direction you'll have the minimum range.

Another hint is to keep the two antennas reciprocally oriented at 90°, one horizontal and the other one vertical, or both at 45°, it doesn't matter. That's true also for the receiver antennas (if it has diversity, of course).

The modding job is quite easy, you have to prepare two 6mm holes and replace the stock antennas with pigtail cables, that's all. Remove the 4 screws on the rear and you'll be able to remove the rear shell, the rear shell must pivot on the handle, there's an internal plastic hook. You should also unplug the battery connector and the external port connector from the main board, you'll operate more freely.

I made the two holes for the connectors on the handle. That's not mandatory, you can put the antennas wherever you want as long as the pigtails can reach the i-pex connectors on the main board.

I've made two holes approximately 1cm far from the handle begin, and i also cut some plastic on the rear shell, in the same place, to accomodate better the cables' path.

There's no advantage in keeping the stock antennas in place, plus they can interfere with the new ones. They are close and they are tuned on the same frequence, of course, so they should be removed. The small stock antenna holder is useless now. It can be left in place but i chosed to remove it and to print a flat cover. Now i only have a better looking transmitter (imho), this won't affect the range at all.

The range mod is done, now you can close the transmitter and use it as it is, or proceed to the next step for the other mods.

Step 4: Additional Features and (way) More Channels

Now it's time to upgrade the firwmare (FW).

This firmware was made by awesome people, they made an outstandig technical work, unluckily the project's wiki isn't very comprehensive and it's not easy to understand by a noob (like me, not long time ago). Ayway, they obviously still deserve a big thanks!

Important: this tutorial is for the FS-I6 and not for the FS-I6X. I don't know what can happen testing this on a FS-I6X, bad things could happen. Look at the picture and check that you have the proper transmitter version.

Important nr2: consider that you could have to redo your models setup on the transmitter and re-bind the receivers.

Now, download this file, in the meanwhile plug the usb/serial adapter in. If you have the specific converter or the FTDI converter windows (at least Win10) should install the right driver without any issue. If you have other "exotic" serial converter like the ch340 or others is up to you to install the right driver.

Assuming that the driver are properly installed, now you need to know the adapter's COM port number. Open the windows menù and search for "device manager". Look at the devices tree, open the label "Ports (COM & LPT)" and identify the adapter's COM number. You can unplug and replug to see which COM was removed.

Now the procedure is different depending on the adapter you are using: if you use the specific adapter just plug it in, if you are using the FTDI adapter use this wiring scheme (scroll down untill you see the FTDI adapter). If you use something else find you own way, it shouldnt be actually difficult to find out the right wiring, but i don't want to give untested hints.

Assuming that the COM port is connected and its number is known, push bot stick bottom-left and power the transmitter up. You should enter a special menù, scroll down untill you see the option "firmware upgrade", enter by pressing OK. Keep OK pressed to confirm that you want to update the FW, then use the up/down button to choose "yes" in the following question and -finally- the TX will let you update its FW!

Now back to the PC. Extract the file from the you've downloaded and execute "flysky-updater-win.exe" or "flysky-updater-win64.exe" depending on your windows version. Execute the .exe "as administrator" to avoid possible permission issue.

First, you need to select the right COM port (unless there's only one, in this case it will be autoselected).

Second, depending on your plan to modify the pysical switches, you have to choose beetween two firmwares. If you don't want to proceed with the last mod choose "fs-i6_updater_01_13_12_08.bin" by tiping "1" and press enter. Otherwise press "0" and press enter.

In few seconds the firmware should be uploaded and the transmitter will reboot. It's done!

Step 5: Better Switches

Now the switches, the least explained mod in the wiki but the most interesting to me.

With this mod we'll ad a 2-pos switch, called SWE, and we'll upgrade SWB from 2-pos to 3-pos.

If you aren't trained in electronics the attached diagrams (from the wiki) could be difficult to understand, not to mention that they show things that don't have to be added, therefore they could be (imho) misleading.

In the two attached photos i've highlighted what i've actually done on the circuit, they are showing the same mod, only different details.

This is the to-do list i've prepared to complete this step:

  1. Drill the hole for the switch, and put the switch in place.
  2. Remove the two cables from SWB's pins and solder them on the new switch, in the same order. Actually, the only mandatory thing is that the cable that was in the center pin will remain in the center pin. The second wire only defines the switch orientation (which lever position means 0% and which 100%, the 50% is not affected, obviously) but the switches can be phisically rotated by 180° depending on the preferences.
  3. Now the old SWB is the new SWE, and the recently added 3-pos switch is the new SWB.
  4. Run a wire from the 3rd pin of SWB, the only one that's free, to the soldering pad called "SWB" in the image (white wire on the right).
  5. Take the 4K7 resistor and bend its legs to match the distance of the soldering pads called "C22". Solder the resistance in place.
  6. Run a wire from the "GND" pad to one of the lateral pin of SWE.
  7. Run a wire from the "3V3" pad to the "SWE" pad. Cut it in half and solder the 10K resistor in the middle.
  8. Run a wire from the center pin of SWE to the "SWE" pad. Cut it in half and solder the 220R resistor in the middle..
  9. Use some hotglue or other insulating methods to add strength to the ne connections and to prevent possibile shortcuts and other bad things (just in case)

Now you can put the rear shell in place and tight the screws, but i suggest to test the new switches in advance, especially their "direction". In the attached photos the switches behave in "my way", basically the opposite you might expect. That's why i've spoken only about center and side pins, there are no "right or wrong" side pins, it depends on your will. If you want to change the behavior you can swap the external pins desoldering and resoldering them or, more easy, rotate the switch by 180°: ^_^

Step 6: Well Done!

Now is time to set up and test your new transmitter!

Itested it using a receiver, with the i-bus output, connected to a flight controller, and i tested everything using inav and/or betaflight configurator. I don't know if there's actually another way to test a transmitter with that much channels. Anyway, these mods are mostly interesting for flight controllers, so...

Next step is whether to add an external module bay or to add more external physical switches and/or potentiometers. The module would be nice for extra long range, and the additional commands to control additional gears on my model (pan&tilt gimbal). For the ardupilot fan, it would be quite easy to add 6 buttons to directly switch between flight modes, avoiding having to going through unwanted flightmodes. You could just jump directly in the mode you want. Let me know in the comments if you like this idea.

I made a tutorial also on receivers upgrade, have a look.

That's all, have fun!