Dx6i signal loss

[Roandb]

Hi,
Recently I purchased a Spektrum DX6i transmitter and ar6210 receiver. I've mounted the receiver on my 250 zmr quadcopter. It's fitted with 5.8ghz fatshark fpv(600mw racing band transmitter). The main receiver is under the video transmitter (mounted horizontally) then the other is mounted vertically next to the flight controller(one antenna to the sky the other to the floor). The transmitter is also pointing to the sky as intended to. I'm also not flying behind myself.

I've been flying and in my area and in a open park with NO obstructions and barely getting 25m out of the craft. It sometimes glitches closer.
I'm wandering what it is. The receiver is a DSMX so better than a DSM2. Is it just spektrum and FPV does not work or the locations of the receiver are incorrect?
Thanks.

 

[PsyBorg]

Receiver antennas should be mounted 90 degrees to each other not 180 as you describe. I usually mount mine in the rear of the quad with one straight up and the other straight out the back of the quad. Then I either run the FPV antenna straight up with a slight bend rearwards to better match where it would be when tilted forward in flight or straight out the back of the quad in the highest place possible witha slight bend up.

Picture giant doughnuts radiating out from your antennas and think where the holes will be. You want as much overlap as possible with the two antennas which is why 90 degrees is usually best.

Depending where you live 600mw requires a HAM certification or is flat out illegal in certain countries. You may be washing out your ability to talk to the receiver if your FPV antenna placement is to close between the two as well at that wattage.

 

[Roandb]

Thanks I'll have to try it, just going to use the old one for now to be sure that'll work.

 

[Craftydan]

I would recommend taking the time to separate the Video TX and the Control RX -- they're off band from each other, but too close with too much power, the spurs-off-the-spurs-of-the-Harmonics are likely powerful enough to blind the Control RX (not to mention some of the weird effects that happen in the "near field" of an antenna -- the area close to antenna where the RF waves are just starting to form).

I'd shoot for 2 wavelengths if you can (~10cm for 5.8GHz), just to get into the "far field". Signal density follows an inverse square law, so even a little bit difference can mean a lot.

 

[Hai-Lee]

The main effect of a tx antenna being too close to a rx antenna is "blocking". The band or frequency of the transmitter does not matter as the transmitted energy actually swamps the rx and can cause changes in the DC operating voltages of the rx front end. These changes basically turn the sensitivity down or in the extreme completely off.

Where possible NEVER fit a tx antenna next to a rx antenna unless you have added appropriate filtering into the rx antenna line.

 

[makattack]

The other thing I don't see mentioned, is that carbon fiber is conductive, and I believe the ZMR frame is carbon fiber. I can't really picture how close the active parts of your RX antennas are close to the CF material, but based on your description, I can imagine one possible configuration is to have them all inside the two CF top/bottom plates, which seems to make a nice little partial tempest room (basically a shielded room to block in/out RF signals) type of setup.

 

[megabotz]

With my current project, I can attest to the fact that carbon fiber plate makes an excellent RF shield.

megabotz

 

[Roandb]

Dx6i tests

So I carried out a few tests:1. I bound the transmitter and walked away with the VTX on.
2.i bound then turned off my VTX and did the same test.
With the VTX off I only got about 5 extra metres of range so I don't think it the vtx.
The photos show this, the quad is next to the lamp post you may just be able to see its green lights (and yes I was getting the same range when it wasn't next to a lamppost). The orientation of my quad, battery was all the same. The VTX antenna was facing me towards the rear of the craft and if this is a bad position for a transmitter it is going to have to do this very often as I fly away from myself. Have a look a the photos Also here is some footage of my quad working with my TGY-i6 transmitter perfectly https://m.youtube.com/watch?v=8u_PZYKDvR0

 

[makattack]

Hmmm... I see now you mentioned you have a newly purchased DX6i... well, assuming you're in the USA, when I got my DX6i (used) from a friend who never used it, I noticed it was configured for EU power output, which is a little less than what the US allows. I wonder if your DX6i is setup the same way. I forget how to change it, but it's pretty well documented.

The other thing is, I would try to get those RX antennas away from the carbon fiber plate and the board with all the pins sticking out... is that your voltage alarm/checker? Those metal pins might be doing something to the signal, especially if a battery is connected to it. Basically, I try to orient my RX antennas away from any metal, conductive material (carbon fiber) or other electronics/wires, etc.

Hope that helps. Also, when you did your test, did you do it in "range test" mode?

 

[Roandb]

When I did my range test no I didn't do it in range test mode I'll check tomorrow with the antennas but my other turnigy tgy-i6 worked fine in the same ish location when it was tied underneath/ to a metal stand off. Thanks.

 

[Hai-Lee]

It could be possible that you have a disconnected/broken antenna either in your Rx or even in your TX. (Flight test has previously shown that even their transmitters can have an antenna lead unplug itself).

When doing your next range test please test with the transmitter antenna vertical and then again with it horizontal to see if there is any significant difference. If there is then you may have a Rx antenna disconnected.

 

[Roandb]

Dx6i update

I did some more tests. I put the Receiver on a piece of wood with 90 degree angles to polarise the antenna. Again I'm only getting 25 m. I thought maybe the 2nd part of the antenna isn't connected so I put the main part of my ar6210 receiver pointing to the sky/floor a but still getting poor range. The VTX is not on either. Starting wander if the receiver or transmitter is faulty and maybe I should just invest in a turnigy evolution as I've had very good results with my cheap turnigy tgy-i6.

 

[Roandb]

I just straightened my antenna so it was upwards still poor range thanks for the idea though.

 

[makattack]

Sounds like a hardware issue, but just another point that probably doesn't affect anything. When I perform range tests, I generally elevate the receiver/model up to a minimum of table height. In a worse case scenario, without nothing higher available as a platform, I've used a chair. Having the RX so close to the ground is a worse than worse case scenario due to RF reflections/clutter/ground issues, etc.

Are you able to pop the cases off either the RX or the TX and verify the antennas are securely connected as others have mentioned?

 

[Roandb]

I had a look the first two photo are off the main board and the last two are the 2nd bit. I see there is a bit of a wire exposed on the 2nd photo and the last photo does show a solder connection that looks a bit cold. But see what you think, thanks.

 

[KRAR]

Doesn't look very good. Horizon is excellent with customer service... contact them directly and see what they say...

 

[Craftydan]

Hmmm . . .

Not that it is impossible to get a shoddy part from HH, but where did you buy this RX from? If you didn't get it from a reputable dealer, There's a lot of counterfeit Spektrum gear out on the market. This is different than aftermarket parts like LemonRX and OrangeRX -- a counterfeit part will have nearly identical packaging and the boards will only be subtly different . . . and are usually poorly constructed with pitiful performance.

Horizon is good with supporting their gear, so if you picked that up from a reputable dealer, they'll take good care of you . . . If not, it's really not their fault if it's a counterfeit -- they didn't build it.

If you don't want to bother with support (they're good, but it's still a hassle), reflow the solder joint and see if it improves. It might void your warrantee (how do they know you reflowed it properly? It's not hard to do, but not hard to botch either), but might fix your problem outright.


. . . While you're at it, you might want to crack the case on your TX and have a look inside for a loose or crimped antenna. The antennas it uses have a press-on connector, so it should rotate around the pin, but it should be firmly attached to the board. Opening the case for adjusting the gimbals is expected, so that won't affect your warrantee in the slightest.

If everything looks OK, the worst you may be looking at is picking up a LemonRX for $10-15 to verify/replace the failed Spektrum RX.

 

[Roandb]

Oh honestly I crash haha, a lot.

 

[Roandb]

I got it from eBay for about £15 off eBay, I just checked and the guy has 100% reviews but he is not a big retailer and has sold only 100 or so items. But they have sold other spektrum receivers and if they were fake someone could of reported. Now I do kinda like the sound of a turnigy evolution or should I just stick with this Dx6i. It's soul purpose will be for FPV and not many models or planes.