Boosting the Range on a Stock Hubsan & WLToys Tx - RC Groups
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Feb 13, 2013, 04:18 AM
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Boosting the Range on a Stock Hubsan & WLToys Tx

I purchased a WLToys v929 and Hubsan X4 as micro FPV platforms but quickly found that the range on both were quite short with the stock transmitter and far too restrictive for FPV flying.

In the following posts I'll cover the steps I used to greatly increase the range on both my Hubsan X4 and V929 stock Tx's. Based upon a non-scientific & non-LOS comparison of the boosted Hubsan and WLToys R/C link and actual LOS results from my other FPV models, I'd conservatively estimate ~1 mile range. Using the same boosted method I've flown 1.25 miles via FRSky link while maintaining >90% RSSI on my EasyStar, and 0.5 miles out with 97% signal on my full sized quadcopter. RangeVideo has obtained far greater 80Km (50 miles) range from a similar booster at 1/2 the power.

For now though here are some videos from initial FPV flights.

Hubsan X4 FPV
Hubsan X4 Baylands 2013 02 12 (5 min 23 sec)

WLToys V929 FPV
WLToys V929 Baylands 2013 02 12 (0 min 0 sec)
Last edited by patricklupo; Feb 13, 2013 at 04:39 AM.
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Feb 13, 2013, 04:19 AM
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A7105-500 Upgrade

The A7105-500M module was my 2nd attempt at boosting the range on my Hubsan Tx (the 1st was to use an SBA-4086Z RF amp to add another stage to the Hubsan's RF output and was a complete failure). The A7105-500M module can be found on EBay, is rated at 17dBm (50mW), and states 500 meters range. Unfortunately those specs are either greatly exaggerated or the sensitivity of the Hubsan X4's Rx is very low. I suspect both to be the case; the module did double my ground test range from 150ft to 300ft but came no where near the hoped for 1500ft range.

With that said, this is a cheap mod for the Hubsan Tx that's fairly easy to install with basic soldering skills. For LOS flying, I felt that the Hubsan's range was terrible and totally inadequate but this completely cures that problem (although with one caveat). It increases the total current draw on the Tx's 4 AAA batteries from 30mA to 110mA. While a basic AAA alkaline battery capacity is ~1800mAH, it's C rating (how much current you can draw) is a bit too low to deliver the increased amperage. I found that with regular AAA batteries my upgraded Hubsan Tx range was always very poor but greatly increased as the AAA batteries 'warmed' up after a few minutes. When I tried NiZn AAA rechargeable batteries, there was no problem and range was always great immediately. Alternatively you could use high current disposable AAA batteries or even a small external 2S or 3S lipo attached to an LM7806 or 6V BEC, to emulate 4 AAA batteries powering the Hubsan Tx. Whatever means you use, the point is that regular AAA alkaline batteries will no longer work very well unless you leave the TX on for several minutes.

If your intended goal is for FPV beyond 300 or 400 feet then this mod is {probably} unnecessary and an external booster is about the only way to get beyond that with these cheapie toy radios. While an external booster is pricer than the A7105-500, it is a much simpler mod that requires far less soldering. See the next 2 posts for more info.

Below are photos of my A7105-500 installation. The module requires 3.3v and the Hubsan's internal 100mA 3.3v regulator is insufficient to power it so you'll also need an LM1117T 3.3v positive regulator.

Parts List:
A7105-500M Aliexpress has these for a bit cheaper but I found they didn't accept PayPal so it was a deal breaker for me.
LM1117T 3.3v
Misc heat shrink
double-sided or servo tape

-You can add an external 2.4GHz omni antenna but the included wire antenna was more than enough range for LOS flying.
-So that the Hubsan power switch also controls the A7105-500, the LM1117T + voltage input should be run from the on/off switch pad on back of the Hubsan PCB (see photo).
-As seen from the last photo below, I cut the 2 traces on the Hubsan Tx PCB (under red circle) to disable the built-in A7105 IC, but feel it was probably not necessary.
-The LM1117T is placed in heat shrink and fits best in the open space in the Hubsan TX handle. Initially I had soldered it directly to the back of the Hubsan PCB but found that there wasn't enough clearance to put the case back together.
-If you snip the header pins off the A7105-500 module, it'll fit neatly under the Hubsan LCD screen. Put some double-sided tape on the metal case and stick it (metal case side down) to the IC under the LCD screen.
-Use care soldering around the Hubsan Tx as it's plastic parts will easily melt if the iron is placed near them.
Last edited by patricklupo; Feb 16, 2013 at 09:50 PM.
Feb 13, 2013, 04:19 AM
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Boosted Hubsan Tx

So after trying the A7105-500 mod and not geting the range I wanted for FPV, I started looking around for something more plug-n-play to boost the range. Like most radios, the Hubsan Tx is 2.4GHz so that meant a WiFi booster. Ideally I wanted something around 100 to 300mW output but WiFi routers already output between 60 and 100mW so no one makes a booster that only amplifies the intended signal a little. Essentially there's 3 mainstream boosters to choose from.

1.Alpha 800mW
2.Argtek 1W
3.Sunhans 2W

I was leaning towards the Alpha but already used a Sunhans on my primary radio with good results, so I went with that. The Alpha is probably also a good choice but there's no indication of the required voltage so it's likely to need a regulated power supply that would add to the stuff to mount on the mini Hubsan radio. If you go with the Alpha I recommend attaching it with an SMA cable, as there's no way to hang it off an improvised RP-SMA connector without it breaking easily. I don't recommend the Argtek as it's too bulky for the tiny Hubsan Tx and the one I had died within a month (the same short lifespan has been reported by other folks in RCG).

The only thing you 'should' need for the Sunhans is an a RP-SMA pigtail soldered to the internal antenna and a small 3S lipo. Finding space to install the pigtail in the Hubsan Tx was the hardest part. Initially I purchased a U.FL connector and U.FL to RP-SMA pigtail but both the connector and wire were too delicate and broke within a week. So I went with a simpler approach and stripped the end off an RP-SMA pigtail with thicker wire and soldered it to the antenna signal out and ground. In my case, I already had the A7105-500 module installed so I attached it to it's antenna out, but there's a pretty good chance you can connect the pigtail straight to the PCB antenna on the Hubsan Tx. Either way, be sure to also solder the pigtail's outside shield wire somewhere to ground on the Tx. The stock Hubsan only outputs 1mW RF power so I can't promise it'll be enough to drive the Sunhans without an A7105-500, but it's worth trying without the module and would be preferable.

Parts List:
Sunhans or perhaps Alpha amp above
2.4GHz Omni antennas - To replace the large one that comes with the Sunhans and for use on the Hubsan Tx without booster.
RP-SMA pigtail - The tiny wire on RP-SMA to U.FL connectors is too fragile, while the gray or copper wires on most pigtails are too stiff, so use an RP-SMA pigtail with black wire which is attached to something like an MCX plug.
Any small 3S lipo - I used a GE Power 900mAH I had laying around because of the size and form factor. Current draw is estimated around 600mA.
JST female plug
Dual-lock strip - Best for mounting the booster to the Hubsan case
Misc velcro and heat shrink

-The back battery cover on the Hubsan Tx is the only place to mount the booster, but it's only held on by 4 small plastic tabs that could break easily. For that reason I used dual-lock, because it mounts solid without requiring a lot of force to remove. You can just as well use velcro but don't go overboard with too much. The Tx supports using a screw with the battery cover so make use it.
-If you get the Sunhans, get one with the 'Sunhans' brand name on it to reduce the chances of getting a knock-off copy. Because the Sunhans are so popular, some sellers are putting Sunhans logos on 1W Argteks as well but it usually obvious from the case style that it's not a Sunhans.
-Here's my thread on using the booster with FRSky.
-As with anything over 0.5W power, don't ever place it close to your eyes or head while powered up.
-Never power the booster up without an antenna on the output.
-Although these boosters are often sold in the US from places like Amazon, you should have a HAM radio license to operate one legally.
Last edited by patricklupo; Feb 18, 2013 at 03:14 AM.
Feb 13, 2013, 04:20 AM
Registered User

Boosted WLToys Tx

Details and more photos coming soon.
Last edited by patricklupo; Feb 14, 2013 at 03:56 AM.
Feb 13, 2013, 05:11 AM
Hubsan X4 - H36 - V911
bangkomit's Avatar
Wow, very interesting. Waiting for your details
Feb 13, 2013, 05:11 AM
Suspended Account
very nice mod i have a 2w booster here i was going to add to a 9x would it be possible to make a 9x compatible module for the hubsan x4?
Last edited by neobot; Feb 14, 2013 at 06:14 AM.
Feb 13, 2013, 05:48 AM
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ripmax's Avatar
Please tell, I like the idear of flying fpv with something that won't hurt anyone if if drops out of the sky.
Feb 13, 2013, 12:59 PM
Quad Erat Demonstrandum
scousethief's Avatar
Very nice , some details please
Feb 13, 2013, 01:15 PM
Registered User
Subbed, in dire need of extending range on the hubsan for FPV purposes!
Feb 13, 2013, 01:39 PM
Finding Creative Ways To Crash
RCCrashTestDummy's Avatar
Feb 13, 2013, 02:20 PM
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richos's Avatar
Feb 13, 2013, 05:10 PM
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Originally Posted by scousethief
Very nice , some details please
Please check back later tonight as I'll be adding the build logs with photos after work.
Feb 13, 2013, 05:22 PM
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MassiveOverkill's Avatar
That's pretty impressive.
Feb 13, 2013, 06:54 PM
Registered User
I can't wait to see the details! Does it have anything to do with these modules?
Feb 13, 2013, 07:34 PM
Quad guys are 4x the fun :)
BD Murdock's Avatar
Very interesting...looking forward to seeing how it's done without upping the power needed.

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