Hardware mods to extend the range of a Devo 10

I have a Devo 10 with the stock antenna and a 4-in-1 module. I'm super happy with it, but I wonder what could be done to improve its range. I mostly fly mini FPV quads with it (using full-range FrSky XM+ receivers), and they're so fast it seems a pity to limit them to the confines of your typical flying field, especially since the video link can be pushed quite a way farther (600mW transmitter + cloverleaf + patch antenna on the receiver). The battery is the obvious limitation, but it lasts long enough to cover quite some distance (including the return trip), and that makes for some pretty spectacular video - if you don't lose your connection and drop the quad like a stone, and as capable as the XM+ receivers are they can't get that far all by themselves.

Basically I'm looking for something I could hack onto my Devo in order to turn it into a poor man's TBS Crossfire. I'm thinking aftermarket antennas and power amplifiers, but I know close to nothing about radio transmission so I don't actually know what I'm looking for (or talking about). I am, however, always ready to be enlightened.

@Fallingwater,

Are you looking for distances over 2km ? I have also a 4in1 modules in my transmitters, and to fly FPV I do not need to go over 30mW to have reasonable range. do some range test with the lowest emitting power. You will be surprised how far you have to go before loosing connection.
I noticed the antennas of the XM+ are 'cut' at 1/5 wave length, better to have them at 1/4 wave length (31.25 mm)

pulpfiction15 wrote: @Fallingwater,

......cut
I noticed the antennas of the XM+ are 'cut' at 1/5 wave length, better to have them at 1/4 wave length (31.25 mm)

Is this rx a from a recent batch with 150mm antenna length in total? My XM+ is an older one with longer antennas and there
the exposed part is a 1/4 wave length. Pretty good range with high RSSI showing on the osd.

For this reason I modded the antennas on my XSR ( exposed part was 26mm) to the same wave length and the RSSI jumped
from 72 at close distance to 86-90 .......
Can´t imagine any reason why Frsky is doing this.

Edit:
Btw, I use the 8channel firmware on the XM+ ( RSSI on channel 8 )

@aMax,
What is 'old' they are about 6 monts old.
I had to re-cut one anntena after a 'blade strike', that was when I noticed the differnce. I did not do it on the other receives because I have no range issues at all.
happy with the xm+

I got mine in February this year, with 20cm antennas.
Regarding your antennas, on a quad the total length does not matter much, but the exposed part should be at least the same,
topic: antenna diversity & rf pattern

pulpfiction15 wrote: @Fallingwater,

Are you looking for distances over 2km ?

Possibly. I'm considering putting a bigger battery on my cruiser miniquad and seeing how far I can push it; it's a low-power design I built specifically for power efficiency (aka the drone that gets the dodgy, fake, second-hand and otherwise low-C batteries I don't feel comfortable feeding to the others), and while it won't do spectacular acrobatics - especially not if saddled with a heavy battery - it's perfectly capable of flying fast.

Also I might eventually try fixed-wings - generally a better idea for range than anything with vertical thrust - and then the whole point would be to go beyond 2km.

I have also a 4in1 modules in my transmitters, and to fly FPV I do not need to go over 30mW to have reasonable range. do some range test with the lowest emitting power. You will be surprised how far you have to go before loosing connection.

I actually had a failsafe with one of my micros at a fairly disappointing range when I forgot the power output set to 30mW after indoor testing. Granted micro BnF receivers suck, but I honestly was expecting it to go farther. I cranked the power back to 150mW and never had another problem, but it left me worried.

@Fallingwhater,

You should then consider a patch antenna 2,4 GHz, and look at RSSI to see if you increase range, problem is that they are directional, and you need to point at your model, not always easy in FPV.

I have found this universal amplifier on Banggood. Apparently you just pass the radio transmission through and it boosts it all the way to two watts. The person who recommended it to me said their range roughly doubled when they installed it.

Your thoughts?

The safest way is to use a long range system like TBS Crossfire, Dragonlink, EZUHF, etc.

2W in 2.4Ghz is illegal almost everywhere and depending on how crap the amplifier is (hint the cheaper it is the more chance you have it's utter shit) you will flood the whole 2.4Ghz band making people inside a certain radius hate you, and there's also the chance (depending on the receiver) you will lose signal at very close range (same flooding issue).

I would advise against using an amplifier.

If you really want to do long range, you should:

1. antennas: use multiple antennas (omni and high gain directional) eventually with a tracker
2. have a good auto pilot system with return to home
3. be prepared to lose you aircraft and eventually plan for it (gps tracker or something else)
4. plan for failures (2 lipos in parallel, etc)
5. test fly close range many many times before antempting long range
6. do not fly over people or properties


good luck