The RCT-Tx24

The RCT-Tx24 is a handheld radio control transmitter designed for use with radio controlled locomotives and is suitable for railways in small to medium-sized gardens or indoors. With direction being controlled with a potentiometer knob it is ideally suited for live steam locos, but the direction knob can also be used with battery-powered locos with ESCs (electronic speed controllers) which have been set-up to be low-off (ie zero speed when the knob is fully anti-clockwise). The RCT-Rx65b can be reprogrammed to be low-off.

The maximum range of the transmitter is around 30m outdoors and 20m indoors, however the signal can be disrupted by buildings, damp foliage, people and the metal bodies of locomotives. It is important therefore to position the receiver aerials in locos to have as clear a line of sight to the transmitter as possible - preferably with the aerial vertical to ensure that it is less likely to face the transmitter end-on. Here are some examples of how receivers have been installed in live steam locos.

Speed / Regulator knob
The speed / regulator control knob controls Channels 1 and 6. It is a 300° rotary control with centre click. The knob can control speed and direction or just speed when used in conjunction with the direction knob. This depends on how the receiver (eg the RCT-Rx65b) has been programmed or how the RCT-Rx102 has been set-up when operating a servo (also see Receivers

Direction / Reverser knob
The direction / reverser control knob controls Channel 3. It is a 300° rotary control with centre click. When used with an RCT Rx65b receiver (see Receivers) which has been set for 'low off', it is used to control the direction of the locomotive. It can be used to operate servo controlled reversing gear on live steam locomotives (with the RCT-Rx102). When used with receivers with 'centre-off' speed settings (eg the RCT-Rx65b), can be used to control servo-operated accessories such as auto-uncoupling devices or to control lighting and soundcard effects. It could also be used to steer a road vehicle or boat.
Inertia knob 
The default purpose of the inertia knob is control the rate at which the speed knob settings are implemented. The inertia knob slows down changes caused by the speed / regulator knob - ie if the inertia knob is set to (say) half way, when the speed knob is turned to a setting, the loco will slowly build up speed when the speed knob is advanced, or slowly come to a halt when the speed knob is returned to zero. When the inertia knob is on its zero setting (ie fully to the left), changes to the speed knob occur immediately.

The inertia knob's function can be changed so that it controls outputs from Channel 4 (or Channel 5) on a receiver. This is accomplished by waiting until the transmitter has been switched on for at least a minute, and then holding down the bind button for around twenty seconds (see RCT-Tx24 instruction sheet). The transmitter will remember this setting (even when switched off) until the above re-setting process is repeated. With the inertia knob in this mode, it can be used to control another servo connected to the Channel 4 (or Ch5) output from a receiver such as the RCT-Rx102. This could then be used for operating, for example, a blower or gas valve.
On/off button
The illuminated push-button turns the transmitter on and off. The LED also provides information for the user - it flickers when inertia control is active (ie when the loco is speeding up or slowing down under inertia control) and it flashes once a second during the binding process (see Bind button below)
Selecta knob 
The Selecta knob uses Channel 2 and sets the RCT-Tx24 apart from most other transmitters. The rotary switch allows 12 locos to be independently controlled. Each loco (or several locos) is bound to one of the switch positions - when the switch is turned to a particular position, it controls whichever loco or locos are bound to that position. When the switch is turned to a different position, the loco(s) bound to any of the other switch positions continue doing whatever they were previously doing. This feature works only with receivers programmed for interpreting Selecta signals  (eg RCT-Rx65-22 and RCT-Rx102). By using this knob, you can control any combination of live steam locos and battery powered locos using just this one handset (I have a label attached to the back of my transmitter reminding me which loco is bound to which Selecta setting).

Bind button
Receivers need to be 'paired' with the RCT-Tx24. The binding process is only necessary once per receiver. To bind a receiver to the RCT-Tx24
  1. The receiver is put into bind mode (eg with the RCT-Rx65b, switch it on and wait 20 seconds its LED to flash rapidly, with the RCT-Rx102, a bind plug is connected across the signal pins 5 and 7). 
  2. Turn the RCT-Tx24 Selecta switch to the position wanted for this loco. 
  3. Press and hold the bind button on the RCT-Tx24
  4. Switch on the RCT-Tx24 and then release the bind button. 
  5. Binding is complete when the LED stops flashing. 
 Once the Tx is no longer in bind mode or when the Tx is switched on normally, the Bind button can be used to control receiver outputs via Channel 5 such as a servo for operating a whistle or for triggering the whistle effect on a soundcard.