Some months ago I had an issue when flying one of my RC planes. A strange plane behavior and without any other flyer around that made me suspect about interferences many from electrical fields around. Landed safely and decided to try another spot but again I noticed interferences.
Besides this I found difficult to buy new 35Mhz receivers as not many on-line shops have them yet to sell.
So it was time to change my setup for 2.4Ghz. However, I wasn't in the mood to buy a new transmitter and a new set of receivers. I'd prefer to "add" the 2.4Ghz ability to my existing radio and incrementally if needed by new receivers.
For my current radio (Graupner/JR Mx-16s) is not just about buying a new module and replace the existing one on the back of the transmitter. However I made some research and found some videos about using DIY modules. They require some soldering but nothing anyone can do (if I did it anyone can do it...believe me).
I decided to buy the FrSky 2.4Ghz DIY transmitter module and with that I would maintain the ability to use 35Mhz, using a switch on my transmitter that would alternate between 35Mhz and 2.4Ghz. With this I could still use my existing receivers (at least the ones I still thrust) and could start using 2.4Ghz ones.
The setup was quite easy. Was just about opening my transmitter, finding the exact place where the PPM plug (inside it) was placed and then prepare the soldering work.
This picture shows that plug (red circle).
The module was placed under this electronic plate and to do it was just about removing the four screws (green circles), place it there and tight the screws again.
I know that cutting wires on a transmitter causes always some "strange" feelings. At least for me it's always too "definite" and I still think: "What if I'm wrong and this was the wrong wire?". But after viewing and reviewing some youtube videos I was quite sure that I was doing the right move.
Notice the blue switch on the top of the picture? Is something new which I'll describe in the next sentences.
I made a diagram of how the thing should be done to be exactly sure (even before cutting the wires) about how it would work:
- Red wires - power
- The red wire that was connecting to the plug was soldered with an extra lenght (blue circle) that now connects to the DPDT (double pole) switch
- I also soldered an extra legth of red wire from the plug to the DPDT
- Black wires - ground
- The black wire that was connecting to the plug was soldered with an extra lenght (blue circle) that now connects to the DPDT (double pole) switch
- I also soldered an extra legth of black wire from the plug to the DPDT
- Yellow wires - PPM signal
- For this one I decided to make a Y-junction. So I soldered the three: The existing yellow wire and the new one (from the DIY module) and an extension I soldered to the existing plug.
The dark/grey circles represent the cutting/soldering points.
After doing this now was time to drill holes on the transmitter. The feeling is the same than cutting wires and it's good idea to drill them as small as possible. It's always possible make them a bit bigger but get them smaller is quite difficult. There are 2 new switches, one antenna, a new led and a press button, so total of 4 holes.
I find that the way the cables would be best placed and also the switches, regarding the available space inside the transmitter was like shown on the next picture:
- On the left I placed 2 switches (blue circle). The red one is from the module itself (switches between the 3 modes of the telemetry capabilities of the module). The blue one is the DPDT switch I explained before and switches between 35Mhz and 2.4Ghz.
- Behind the 35Mhz antenna I placed the 2.4Ghz new one (red circle)
- On the right I placed the led and small press button (yellow circle). The led gives information about the sync state between the transmitter and receiver. If 35Mhz is selected (blue switch) the led is off). The small press-switch is used to sync (first time) a new receiver is used.
So, after finishing the transmitter looks like this:
I already use it and it turns to work as good as expected. Before each flight is a matter of confirm the band of the receiver being used and change the "blue" switch accordingly.
If anyone is interested in doing something similar and has any doubts, please email me and I'll be more than happy to help: ffbento@gmail.com
-Frank
