Choosing the right servo Extension

Hey Flite Fam!!

Ever wondered how to choose the ideal servo extension for your Model aircraft?, Is JR type better than Futaba & what are the differences? This article will explain all your these things in detail and help you select the best servo extension for your aircraft

First lets go into the particular details that separate the JR type and the Futaba type connector.

If your not into comprehension you can watch this video.

1.Wire Colour

The First notable difference is the colour of the wires, in a JR type extension the wire colours are brown, Red & Yellow.The brown being the negative the red being the positive & the Yellow the signal wire. While in a Futaba Type its Black red & White. To not get confused with polarity all you have to do is to remember that the lightest colour is always your signal wire, which is yellow in Jr and white in futaba and the darkest colour is always the negative lead. Also you can get some JR Extensions in Black red and yellow as well as twisted wire extensions

JR Extension Polarity

Futaba Extension Polarity

Signal is always the Lightest colour

Twisted Wire Extension

2.Connectors

The connectors are the main difference between the two extension types. Lets first look a the JR type

2.1 JR Connector

The JR connector has a feature called safe connect. This is basically to prevent you from accidentally connecting your servos in the wrong polarity which could damage your servos. This is done with the help of angled tabs in the Female connector along with the presence of chamfered edges on the male connector.

Safe Connect Design

2.2 Futaba Connector

In a Futaba connector there is a big tab in the signal side of the female connector, but the Futaba Extension i had, didnt have a similar tab for the male connector, which means you can still connect the servos in reverse if you didn't pay attention. 

Futaba Connector Design

2.3 Is a JR and Futaba compatible?

The Answer is "Yes" they can be connected without any modification.

JR Connected to a Futaba Extension

2.4 Why some JR extensions with Safe connect wont connect to some Servos:

Depending on your servo, they sometimes refuse to connect to a JR extension, as is the case of a typical 9g servo, This is due to the fact that the male end of the servo is square around the edges while in a Jr and Futaba extension the male end is camfered(smoothened) around the edges. So to be able to connect the servo To a JR connector, you'll have to slightly sand the top edges. Once sanded down they can be easily connected.

JR male connector vs Servo male Connector

Sanding down edges of Servo connector

3.Wire thickness & Weight (AWG)

A common factor that determines flight performance is the weight of the aircraft, and this can be influenced by the electronic components used in the aircraft. One such component is the extensions. Wire weight is heavily influenced by the length and the thickness of the wire. The wire thickness is usually signified by a measure known as American Wire Gauge(AWG). In this gauge measurement the higher the number the thinner the wire & the lower the number the thicker the wire. 

12AWG & 14AWG Wires

So to demonstrate the weight difference, I measure the weight of two JR extensions of same length but different gauge thickness, one at 26AWG and the other at 22AWG. It turned out that the 26 guage wire was 2 grams lighter than the 22 gauge wire which is almost one third less.

22 AWG vs 26 AWG Weight Comparison

4.But is lighter weight always better?

The answer is "NO". If your making a large model with high torque metal gear servos a thicker lower gauge wire is preferred as it promotes better current flow, but in the case of a lightweight model which uses 9-13 g servos the lighter 26 gauge wire is ideal as it keeps the weight low and plus the servo itself comes with a 26 gauge wire13g & 9g Servos

5.Servo Extension Alternatives

If servo extensions are unavailable or overpriced in your locality, the best alternative s to use jumper cables( Male to Female).

Jumper Cables

6.Conclusion

Comparing both the type of connectors, in my opinion the JR connector is better because of safe connect design, but its incompatibility with some servos and the need for modification leaves the choice open to preference. I am not sure if the Futaba connectors absence of a tab on the male end, resulting in a lack of safe connect, is just my sample or if its the same for every Futaba extension. If so with safe connect the Futaba would be a better choice, but at the end of the day availability and price also play an important role. 

I hope this article helped you understand the differences and influenced which type of servo extension to use in for the various applications