Thread Tools
May 21, 2015, 05:21 AM
Registered User
gordinir8's Avatar
Thread OP

Fpv signal loss after 50% or more throttle.

So I have installed a boscam 600mw rc tx on my dji f 450 e300 quad.
When I am opening throttle at take off power I have total signal loss.
Before the installation I first test it to a brushed motor buggy and had the same problem but I thought it was because of the old motor.
Power comes from one battery but I have also test it with separate batteries and it was the same. I have checked antennas and I also put an lc filter to the video tx with no change at all, I have manage a couple of times to fly it but nothing I can trust, problem most of times is there.
Any ideas?
Sign up now
to remove ads between posts
May 21, 2015, 10:44 AM
Registered User
DanT's Avatar
More then one thing can make this happen .
Guess ,, bad wiring ?
Bad VTX even if is new..
Not on the right channel with both VTX and receiver ...
Tip ,, most would tell you ,, We need pictures of your setup ..
You don't say what camera your using ? Or even what ? Goggles or Monitor ?
How about,,, what antennas are you using ??? Are they the right ones for your setup ????
Some cameras don't like 5 volts ..????
If running off of VTX ???
May 21, 2015, 12:04 PM
Registered User
gordinir8's Avatar
Thread OP
OK here are some details of my setup:
Wiring is ok i guess.
Both channels are paired and try in more that one channel and freq.
My camera is 12volt NOT 5v and takes 12v
I am using HK quanum monitor.
Problem is the same with stock or fatshark antennas and yes i have the correct RP-SMA male plug.

Today i removed all the equipment from the quad (used ofcourse seperate battery ), apply throttle and as soon as i brought the Vtx in a distance of 50-60cm close to the quad i lost picture!!
Moved the Vtx with camera and battery far away from the quad and picture came back again. lower throttle below 50% and picture is ok.
I am using a filter in my setup.

May 21, 2015, 04:16 PM
Registered User
DanT's Avatar
Well I'm only guessing here and this is what I would do ,
If you have extra equipment .
Bad Filter ?
Not if your using separate battery for testing , Your not using same Ground from flight setup in this test ? Like on camera or VTX right?
If you can take one thing at a time and replace it with one from a friend or spare you have?
Another thing,, shut off GPS and see if camera works then?
They say to never run ground from one thing to the next .. Like using ground wire from GPs to VTX ground to Camera Ground..!
Run all grounds separate to Battery ground wire!!!
Don't tap into equipment grounds I'm told interference will build up from one to the other...
Do not run ground from speed controllers to any FPV equipment ever!
Move VTX antenna away from camera they don't like to be next to each other on my setups ... LOL
When I run board cameras I put them in metal case they give off a lot of interference I have found .
Also,, that camera , your running ,, well you might want to try another one that you know works good?
In your pictures ,, it looks? Like you have many grounds taped together Bad idea! For FPV or GPS! For motors using the same power tap and ground,, ok but not for anything on FPV or GPS tap these one at a time only to battery ground wire.!!
My money is still on VTX
Have a friend put these parts one at a time on your setup and see if it works?
What do you see when the video goes bad ? Horizontal Lines moving up or down on the screen Or ?
I would start testing if you can by replacing VTX then camera then ??
Its great if you can test by replacing things ..
Last edited by DanT; May 21, 2015 at 05:09 PM.
May 21, 2015, 11:50 PM
Registered User
gordinir8's Avatar
Thread OP
Well I am using that power distributor that dji supply with the f450 to connect all my wires. This is connected direct to the battery so it has power on it and I am connecting all of my wires there. But since the total loss of signal comes even with the whole system disconnected and separated from the quad With its own battery I don't think that has to do with bad ground. I want to test two things first, new camera and camera wiring and another vtx. But before this I will build a new shielded camera wire.
Can I use a handycam with video out for testing?
May 22, 2015, 12:20 AM
Out for a rip are ya, bud?
Roland Pitchmore's Avatar
My Boscam FPV gear uses RP SMA connectors. Do the connectors on your antennae match the ones on your VTX / VRX?

Edit: sorry, I re-read your post
Old May 22, 2015, 02:13 AM
A moderator felt this post violated the following rule: Highly Offensive Content (Immediate suspension). It is temporarily hidden while sabangzhi edits it.
May 29, 2015, 03:40 PM
Registered User
gordinir8's Avatar
Thread OP
Ok problem solved and i think you must know what was wrong. Well it was the audio cable between receiver and quanum monitor,. As soon as i disconnect it everything was normal. I also test this on a second pair of receiver/monitor and it was the same so quanum display doesn't likes audio cable connected. (there are no speakers on it anyway)

Quick Reply

Thread Tools