Last Sunday, a lot of us who are new to electric pattern got to discussing installations and the subject of a choke came up. One person indicated that it is a good idea because it protects your receiver from interference from the ESC. Another person said that it wasn't necessary because the two components are on different frequencies and there is no interference.

So, is a choke necessary? ....enquiring minds want to know

For most high power electric setups a choke is important.

Unless that is you are flying on 2.4GHz. So far my Plett/Schulze/AR9000 Spektrum setup is faultless with no choke.

Malcolm

I started flying with a RF choke on my first plane and each plane since, so can't say it helped or didn't on my planes. However, I have seen others at my field fail range checks, install a RF choke and then pass the range checks. Basically, I look at them as insurance.....

Woodie

I'll second Malcolm's experience. I bought a Vanquish plane/motor/esc package. The esc came with a choke. I removed it prior to the first flight. With my Spektrum AR7000 I've flown the plane nuumerous times to the limits of my vision with no problems. On the lower frequencies a choke may be helpful.

Allan

Well here is some other info that will help, twist the wires from the motor to the ESC. This will cut down down on the EMI. I have done it both ways with and without. and when I have used them it is small as a pencil eraser and it is only on the signal line.. I can take a photo if needed.. almost no weight.

Scott Anderson
Team Castle Creations
Team Tanicpacks.com
K3GOL

I flew for ~ 1 year of e-pattern without a choke with no problems. I then ran into a few guys at the field who had some issues that a choke solved. I installed one and have still never had an issue. As Woodie say's, "it's cheap insurance".

Take care

Jon Carter

Chokes are too often employed, and very often incorrectly applied.

First you need to find out if your set-up even needs a choke. Take it out for a range test, with the motor running at about half throttle. If the servos are jittering, its pretty clear you've got noise issues. If the thing is rock solid...forget the choke, you dont need it.

There are two ways noise can get into the RX.
Radiation, and Conduction.

Radiation problems normally only occur with brushed motors, and are rare with brushless setups.
If you are running a brushed setup, and the motor is sparking....its likely the cause of your noise problem because of radiation.
There is a simple solution. Adjust the timing to reduce the sparking, replace the brushes, or replace the motor.
If that still doesnt work, you can put ceramic caps on the motor to get rid of the noise.
You can also use a choke...the choke should be applied as close to the motor as possible.

Only apply a choke if ALL other means of removing the RF interference have failed.

Conduction is the likely culprit in a brushless setup.
Usually its the result of the ESC cable to the RX vs motor or esc interference.
Any two wires placed parellel to each other WILL pick up noise. And since the cable to from the ESC to the RX is all parellel wires(three wire servo cable)...it tends to pick up and transmit quite a bit.
The simplelist possible solution to this is to twist the wires. Really....thats all....
Twisting the wires not only can remove the wires ability to pick up noise....it can also remove the wires ability to generate noise.
So you can also twist the wires that feed power to the motor to prevent them from dumping RF.
One other option for removing the noise is to switch to a seperate BEC. ESC's with a built in BEC, are pulling power for the ESC from the same source as the motor, and can transmit noise right into the RX.
By switching to a seperate BEC, you can remove that high freq ESC noise from the RX circuit. Another option would be to use a OPTO ESC. The Opto has the RX signal isolated from the high freq power circuit.

If you do decide to use a choke...last resort.

Fix the problem, instead of masking it with a choke.

Pretty much all high end ESC's used in electric pattern are Opto-coupled and have no BEC.

An RF choke is a perfectly acceptable way to remove the RF noise generated from the switching freq. of the esc.

BDAVISION,

Interesting reply. I'm new to electric and I am trying to anticipate any problems which is why I asked this question.

I will be running a Dualsky 6360 12-T brushless outrunner and a JETI Advance 90 plus ESC (no BEC).

If I understand you correctly, twisting the cable between the ESC and the receiver will reduce the cable's ability to pick up RF interference.... correct?

Terry

Terry, my experience here with similar to what you are going to be using.

I fly Airtronics. Never had any interference problems.. I fly the Dualsky 11T right now with the Jeti 90. I recently changed out to a newer Jeti 90 esc, and got locked out 2 to 3 flights per trip to the field. Nearly lost my Abbra several times. I changed back to the old esc, and have had no problems since.
Now this other esc had several flights in another plane with no problems ever. Strange, I know. Not sure I will choke it in my next plane, but I will if I need to..

Chris

I had some issues using an AXI5330/FAI and a CC HV85 ESC. I was not getting a good range check with the motor going. I used one of the Noise sinks ( http://www.multimodetech.com/ ). It has worked really well for me.

Emory

tewalker01

Yes, twisting the wires will reduce the ability for the wires to pick up and generate RF noise.
Each wire has its own field that can generate noise, by twisting the wires around they cancel each other out.
It also reduces the ability for the wires to act as an antenna.

You can also buy pre-twisted wire.

This tip has been used by phone companies and car stereo installers for decades. Even some of our servo manufacturers (like hitec) have servos with twisted cables for this reason.