Identifying your R/C Transmitter and the trainer socket:

The socket usually resides at the rear of the R/C Transmitter. Do not confuse it with the charger (DC) socket.
Find the socket with the four small holes inside a round area with a notch and a rectangular hole:

What you will need: 

1. Four-pin mini-DIN plug that fits into the trainer socket:
   
2. One 3.5mm audio (mono) jack that fits into the your sound card’s audio input (e.g. Microphone) .As in the following figure:
3. About 2 meters of cable by which you will connect your R/C Transmitter to the sound card sound card. The cable should consist of 2 or more electrical wires. It is preferable that the wires will be coated with insulators of different colours so you can distinguish between the two.
4. Soldering equipment.

Soldering:

• Use the connection diagram to guide you in your work.
• The plug is viewed from behind the plug, the way you see it while soldering.
• The signal line (red) connects pin 1 to the central tab of the audio jack.
• The ground line (black) connects the plug's metallic shield  to the external tab of the audio jack.

Some transmitters feature several types of channel mixing and CCPM.
You need to disable all of them for simulation.
Do not forget to enable them before you get out to the field!

What is Channel Mixing?

In general, every servo on board of your model is controlled by one channel of data transmitted from your transmitter and received by the receiver. There is always the Throttle channel and there are almost always additional channels for the three basic axes: Yaw, pitch, and roll^[1], usually marked by the corresponding control surfaces: Rudder, Elevator and Ailerons^[2]. You would expect that the two sticks of your transmitter, each having a latitudinal and a longitudinal movement will correspond to these four channels.  This is true unless channel mixing is applied.

When channel mixing is applied, moving a stick to one direction affects two or more channels at once. For example, some transmitters offer to mix Rotor Pitch (PIT) channel (Ch6) with the Throttle channel (Ch3) so that moving the throttle stick affects both channels.

What is CCPM?

Some model helicopters feature Cyclic/Collective Pitch Mixing (CCPM)^[3]. This mechanism requires a corresponding CCPM state in the transmitter controlling the helicopter.

Such helicopters are equipped with a swashplate^[4] that is controlled by three servos. In order to tilt the helicopter to the side (Roll), to move up and down (Throttle) and possibly to tilt the helicopter forward (Elevator) all three servos need to be activated simultaneously. For example, moving the transmitter's Throttle stick will result in data change on three channels.

How to disable?

Some transmitters (e.g. 0406A) are equipped with a set of DIP switches inside the battery compartment^[5]:

1. Remove the 3rd battery from the left from the transmitter (looking at rear). 
2. You will see a square slot showing the inside of the TX. 
3. Look within the slot you will see a little red block labelled 1 & 2 with on at the top, with two small white sliding switches protruding (a DIP switch) 
4. Move carefully (using a pen or another small blunt object) switch 1 UP (to on) 
5. Move switch 2 DOWN (away from ON and toward the number 2) 
6. Insert the batteries. Plug In. Turn On. The Simulator should now respond correctly to the transmitter. 
7. Remember to reverse the process before flying with the transmitter.