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Old Aug 13, 2015, 04:32 AM
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5.8Ghz and 2.4Ghz interference???

Hi all,

So just built my APM quad and I have an RC305 RX and TS351 TX for FPV. They both transmit at 5.8Ghz and I am using cloverleaf antennas.

My quad with the turnigy i6 runs on 2.4Ghz.

However, when I have the radio TX and fpv TX both switched on, the fpv display flickers severely - indicating some interference!?

Why should this be if I am using two completely different frequencies?

thanks!
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Old Aug 13, 2015, 08:21 PM
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Not enough juice to power the cam and vtx? Probably. Check your current (A) requirement and make sure no 'ground loop' problem in your setup.
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Old Aug 14, 2015, 04:32 AM
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Have you tried a filter?
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Old Aug 14, 2015, 05:58 AM
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Originally Posted by ican3d View Post
Not enough juice to power the cam and vtx? Probably. Check your current (A) requirement and make sure no 'ground loop' problem in your setup.
Pretty sure current isn't a problem because I am using an 8400Mah 35C Lipo.


What do you mean by the 'ground loop'? I have the camera and vtx grounded to the GND of the minimosd.

Thanks!
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Old Aug 14, 2015, 05:59 AM
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Have you tried a filter?
Sorry, am new to the hobby, which filter are you referring to?

Thanks!
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Old Aug 14, 2015, 06:36 AM
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http://www.sierrarc.com/index.php?ma...roducts_id=361

http://www.sierrarc.com/index.php?ma...roducts_id=361


Most just make their own filter. You need a Schottky diode, Capacitor or two, and an inductor.



.
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Old Aug 15, 2015, 05:37 AM
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Originally Posted by RC Man View Post
http://www.sierrarc.com/index.php?ma...roducts_id=361

http://www.sierrarc.com/index.php?ma...roducts_id=361


Most just make their own filter. You need a Schottky diode, Capacitor or two, and an inductor.



.


Ok thanks.

What type of filter would I need? An LC filter? A toroidal ferrite filter?


Would something like this be a good buy : http://tinyurl.com/okwdapl


Thanks for your help.
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Old Aug 15, 2015, 08:25 PM
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you could make one yourself for less that might actually work a little better but that is basically what people make
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Old Aug 16, 2015, 04:34 AM
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I have never understood why people spends lots of money for FPV but are too cheap to buy or make a good filter that actually works.


.
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Old Aug 16, 2015, 08:01 AM
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Quote:
Originally Posted by tambeshakunt View Post
Pretty sure current isn't a problem because I am using an 8400Mah 35C Lipo.

Thanks!
Doesn't matter what your LiPo rating are if your 5 or 12 volt regulator/supply/BEC can't handle the current required by the VTx and camera.

However, you indicated it only occurs when both the vtx and RC tx are both on at the same time which likely means you need a filter as other suggested. If it was a current issue, it would likely happen regardless of the Turnigy TX's power state.
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Old Aug 17, 2015, 05:38 AM
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Ok thanks. Well I am not using a BEC, I am using a PDB and have connected the vtx & camera straight to the lipo .

I have ordered the lc power filter and once it arrives and I have installed it, I will let you know if it helps.

thanks.
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Old Aug 19, 2015, 05:04 PM
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UPDATE: Got the LC filter and installed it. Made sure it was installed correctly.

However I don't think it has fully solved the problem and now I'm seeing some new problems (or maybe I didn't spot them before idk).

- The flickering video is now random - sometimes it happens sometimes it doesn't but it definitely NEVER happens if the radio TX is off.

- When I increase power suddenly to motors, the minimosd disappears?! Doesn't happen with smooth power/ throttle, only with a sudden change.

- The flickering, when it happens, increases with motor speed
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Old Aug 20, 2015, 03:53 AM
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Looks like you are not the only one to have this problem:

http://www.rcgroups.com/forums/showthread.php?t=2341809

edit:

Ok, I have done some more research into this and it seems that some CP antennas are very sensitive to RF harmonics. You should try removing the VRX antenna and see if your RC TX still interferes with the video (do not remove the VTX antenna while the power is on). Then try the old dipole rubber duck antennas on you VTX and VRX. If things improve try some different CP antennas.
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Old Aug 21, 2015, 04:15 AM
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Looks like you are not the only one to have this problem:

http://www.rcgroups.com/forums/showthread.php?t=2341809

edit:

Ok, I have done some more research into this and it seems that some CP antennas are very sensitive to RF harmonics. You should try removing the VRX antenna and see if your RC TX still interferes with the video (do not remove the VTX antenna while the power is on). Then try the old dipole rubber duck antennas on you VTX and VRX. If things improve try some different CP antennas.

That video is exactly what I'm experiencing. I will give the original dipole antennas a try and report back. thanks!


Still can't figure why the minimosd is cutting out with sudden throttle changes though


thanks for the help.
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