Inopo AFM1 transmitter converted to 2.4GHz using the HobbyKing 2.4Ghz module
I had planned to convert the older AFM1 I have after successfully converting the AFM2.
The Inopo AFM1 and 2 where a great starting point since they are computer radios with 10 model memory and many settings. They are also available on the Internet bundled together with cheap Mini-z clones.
Yesterday I found some time to do the conversion.
Everything went great even though the PCB layout was very different on the AFM1. It does not have the module slot found in the AFM2 and the main PCB is very different.
I bought the HobbyKing 2.4GHz module this time instead of the 4ch transmitter (cheaper) and desoldered the RF-module from the main board that houses the bind button and voltage regulator logic.
When I opened the AF1 I was met with a PCB that looked much worse than the AFM2. It had sloppy soldering, dirt, fingerprints etc. all over the PCB. A sad sight
I really hope for the workers that the AFM2 and later reflects improvements in working conditions!
The AFM1 had a RF board connected to the main board through three wires marked as GND, RF and Volt. I tested these signals and the PPM (FM) seemed to be similar to the levels experienced in the AFM2, but the volt showed ~11v (most likely the remaining battery voltage as shown on the lcd display)
I started to look at the main board in the hope of finding a point marked with 5v and was extremely pleased when I found several 5v markings! That made my job much easier.
I removed the RF board and the wires connecting the board and soldered the 5v, gnd and ppm signals to the 2.4GHz board using the existing solder tabs that had been in use for the old PPM and GND wires.
I also added a standard battery on/off switch where the AM crystal used to be with hot glue after having removed some of the internal plastics to make the switch more accessible. The bind switch was then soldered to the Bind pin and GND pin on the 2.4GHz.
I initially thought about creating a bind plug similar to the one that is delivered with the 6CH HobbyKing receiver and actually made it using an old three pin servo cable that was cut down to two holes and soldered together. It worked great but was rejected when I got the idea about mounting the switch in the crystal opening.
Unlike the AFM2 I also had to Dremel out some of the plastic in the antenna opening since the molding was a little different (deeper). It was a quick job and I the used a good amount of hot glue to fasten the 2.4GHz antenna in place.
That was all. I have now assembled the transmitter and tested it successfully
PS: I suggest that people buy the 3ch 2.4GHz FlySky made pistol grip transmitter instead of buying and converting an AFM1/2/3. This post is meant as a build log for people with old unused AFM1 transmitters. The FlySky transmitter uses the same rebadged HobbyKing 2.4GHz module that I butchered to mount in the AFM1. It is at least available (although out of stock) as an Eurgle branded transmitter at r2hobbies.com.