[BillyJones]

Hello

I have a Cheerson CX 20 quad and have a lot of video interference. I have tried hooking the power direct from the quad to power my FPV gear. I have tried running the power through a power filter. I have also tried a seperate battery to run the transmitter. All to no avail.

I have attached a couple of pictures to the thread to see if any of you FPV guys can see my problem. The wires in the landing gear are for the radio reciever, I thought that I would look into moving them, I was thinking that the radio reciever antenna, especially the rear one might be too close to the video antenna.




Thanks and any help will be greatly appreciated.
Billy Bones

[bcsaltchucker]

1/ be sure you are on the right frequency. There are usually a couple other freqs you can use and see vidoe, but it is really sketchy video once you move any distance away
2/ try it with a separate lipo and motors running. If the interference goes away, then you know your power filter is not the right one. You can make your own LC filter for pennies, but should have carefully selected ferrite and capacitor
3/ can also shorten the wires going from vTx to the camera - the shortest possible gives the best results. Or use shielded multistranded cable

[ror]

I assume somewhere in the quad is a BEC, is it a linear BEC?
A switching BEC produces a lot of noise.

[BillyJones]

Hello Ralph

I don't know if a BEC is built into the quad. What is a BEC and what does it do?
This is my first attampt at FPV, so I am a rookie with the setups. Was also told to shield the wires from my camera and video transmitter. This makes sense to me, with the four motors on the quad they have to produce their own electrical field.

Billy Bones

[bcsaltchucker]

BEC is just a voltage regulator, either linear or swtiching. Usually giv eout 5 or 6 volts. Since you are using Boscam stuff like me, we do not use the BEC at all for FPV, so lot less worry about BEC noise. However the ESC/motor system will feedback a lot of voltage resonation noise so you still need a an LC filter. I found the two LC filter I bought online are not tuned to the freq of noise I get from my RC motors, but when I made my own and chose caps with better specs, the noise is 100% gone.

this is the technique I use for LC filter:
http://www.rcgroups.com/forums/showp...7&postcount=14

you put it in line from the main power system before it splits for the cam and vtx. ferrite first, then cap.

just buy the caps in a bag of 50 for a few dollars, and a bunch of ferrites from hobbyking for dirt cheap two, in a couple sizes.

--

oh and one other thing: there are some BAD BAD vtx out ther what will cause this noise too. A lot of the cheap vTx advertised as 32 channel 600mW are notorious for having or later developing their own interference noise. If you are using E-band (eg Boscam) band of 5.8GHz transmitters, then only use the TS351 or the TS353, which are proven, reliable, inexpensive and high performing. 200mW or 400mW. These are the only ones I will use and happy to do so. http://www.surveilzone.com/5.8g-8ch-...smitter-ws1141

[ror]

Originally Posted by BillyJones

Hello Ralph

I don't know if a BEC is built into the quad. What is a BEC and what does it do?
This is my first attampt at FPV, so I am a rookie with the setups. Was also told to shield the wires from my camera and video transmitter. This makes sense to me, with the four motors on the quad they have to produce their own electrical field.

Billy Bones

You are not using a BEC for the FPV but there is still most likely one being used to power the Rx/controller in the Quad and it is connected to same battery as your FPV stuff..
Is the noise there even when the motors are not running ?

[BillyJones]

Hello Ralph

There is no interference until I crank up the motors and it gets worse when I increase the throttle. I have tried a power filter and even tried using a second battery to power up the FPV gear. I have tried puting the antenna right side up and covering the cable from the camera to the Tx with aluminium foil, all to no improvement.


Billy Bones

[BillyJones]

Hello Scott
I will try to make an LC Filter and let you know how it turns out. Being a rookie at this is frustrating.

This is the system that I have...
http://hobbywireless.com/58-ghz-syst...and-p-825.html

On the "F" band
- TXV584 5.8 GHz 400mw transmitter
- R5800 5.8 GHz receiver


Thanks
Billy Bones

[bcsaltchucker]

Originally Posted by BillyJones

Hello Ralph

There is no interference until I crank up the motors and it gets worse when I increase the throttle.


Billy Bones

yeah go for making the DIY LC filter. I recommend it.

SInce you get no noise until motors running, it is obvious the BEC is not causing any noise.

[BillyJones]

Hey Scott
Before I go ahead and make up an LC Filter I would like to ask a couple of questions.

1. Is this the same as a Fat Shark power filter?
2. I can run the power direct from the quad, there are plugs on the bottom. Or I can run the power from the balance plug on the battery and through the Fat Shark power filter and put the LC filter before the video Tx. Which is preferable?

Thanks
Billy Bones