Hi!
I have 5” quadcopter with an analog VTX. The VTX works OK when the drone is not armed.
When I start flying the signal sometimes get lost.
Is there some way or best practice to test the drone without propellers, but with with high currents, to see what causes the VTX disturbance?
It is much more convenient to find and solve the source of disturbance on a nice warm room than out there on the field, in -5C temperature. But I need to remove the props to be safe.
Thank you!
Without props you can’t get the current flow high enough to get much value. It’s like revving your car when it’s in neutral - a little bit of throttle makes a lot of noise, but the same amount of throttle in gear doesn’t get you out of a parking spot.
In the “old” days, we used to flip the props over and put them on the next motor to do the calibration for the compass. That would let you spin up the motors but they would “push” down. With the development of Magfit, and especially the magfit webtool, nobody does that any more because it’s scary AF! It’s not safe.
Is your VTX switching power modes? Pit or low-power on the ground but not switching when you arm/fly?
Hi!
When it’s armed and flying I can set the VTX power to 800mW. I have two receivers: A small TFT screen with built in receiver and another receiver with HDMI output.
The screen on the analog receiver flickers when I fly, even when I’m close to the receiver. The receiver with HDMI output displays a blue screen with NO SIGNAL and there’s no screen for a second.
I tried different antennas both on VTX side both on receiver side.
So I would like to find the root cause (incorrect wire routing, or add a filter cap to VTX PSU etc) at home, without props.
I have done a current calibration with the “flipped prop” trick. I zip-tied the quad to a chair and I went several meters away. It was scary as hell, as you wrote 
Since then I bought a different battery meter, where calibration is not needed.
Yepp, I think without props the motors are in “idle” just like a car, but I thought there is a “trick” that I don’t know yet
At 800mW, it should work well at close range. Don’t overlook the simple stuff like antenna connections, placement and polarization. What kind of batteries are you using? I’ve heard people having issues with LiIon batteries getting in the way.