Servo Extensions and Y's

The best for giant scale aircraft.
Check out our "Organizers" section to keep all your wires organized!
Note on twisted extensions: If you are still using 72 or 50 MHz transmitters instead of the new 2.4 GHz or Spread Spektrum technology, twisted wires are suggested. If you are using the new technology, twisted wires offer no advantage to untwisted wires. Twisting extensions eliminates interference caused by stray signals being picked up by the signal wire in the old MHz systems. The wire can act like an antenna. This is rarely a problem, but if you have an intermittent interference problem this may be the cause. The signal wire (usually orange or white in color) has little current running through it. It tells the servo what position it needs to be at. The red and black wires have higher current in them as they provide power to the servo. Only the signal wire will pick up stray signals due to the low current. Twisting the wires in effect wraps the signal wire around the power wires which cancels out electrical noise. The noise is called electro-magnetic interference, abbreviated to "EMI". Typically extensions which are around 3' long cause more problems because they are the length of a receiver antenna, but extensions of any length near a gasoline (spark) engine ignition system can pick up EMI from the engine's ignition. DA, 3W, ZDZ, and other ignitions are now shielded so well that this is rarely a problem. Also, resistor sparkplugs are used which keep EMI down. For these reasons, we offer only twisted wires.
TBM SERVO EXTENSION TESTING
TBM conducted its own servo extension testing using the equipment shown. We found that adding a single servo extension (22 gauge with universal connectors) between the Rx and the servo will cost you 1.5% - 5% of your power to that one servo. Adding another extension will cost you another 1.5% - 5% and so on. In one of the many tests run, I put ten 6"extensions in series and measured a total drop of 15% of the maximum torque that a single JR-8711 could put out. In another test, I put ten 48" extensions in series (40' of extensions) and found the drop in power to be 55%. Therefore losses due to servo extensions is a combination of plug losses and wire resistance losses.
POWER LOSSES IN SERVO EXTENSIONS
| SERVO EXTENSION LENGTH | EXPECTED TORQUE LOSS |
| 6" | 1.5% |
| 12" | 2% |
| 18" | 2.5% |
| 24" | 3% |
| 36" | 4% |
| 48" | 5% |
WHAT'S THE BOTTOM LINE OF THE ABOVE TESTING?:
* With proper servo sizing, you will not experience any difficulties using extensions.
* Never use extensions between the battery and the Rx. If you need more length, splice in additional 18 gauge wire.
* Use the shortest length extensions possible.
* Use one long extension instead of 2 or more shorter ones.
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