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Dec 02, 2018, 02:36 PM
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Antenna Mod for HS700/MJX B3Pro tested 2.35Km

The images and Videos below are related to boosting the range on a Holy Stone HS700, which is an OEM'd MJX Bugs 3 Pro...

It would seem that these mods will also work on the other Bugs variants like the 5W etc...

The stock config of the HS700/B3P was tested out to 1.25Km right out of the box, which I thought was pretty impressive given the doc's and marketing blurbs all claimed 800 meters.

Holy Stone HS700 range test approx 1250 meters (3 min 35 sec)

I should note that I did NOT use the stock camera as I think it's just not that good... Although it is in fact 1080p it has a low frame rate (25fps, i think) and it responds poorly to fluctuations in lighting... Instead the initial range test was flown using a Turnigy Eclipse 2K camera mounted in a matching Turnigy Eclipse FPV cradle.

The FPV cradle provides 600mw of power, so keeping the Drone's Video feed live was possible.

Unfortunately the HS700 and the B3Pro both use a proprietary Battery connector and cage that don't offer a 2s Balance plug, so I did have to add a small 500mah 2s cell to power the FPV Tx.

Per the Pic's below, the first step was to upgrade the Antenna in the TX/Controller unit. pretty straight forward, pull the Batteries, crack open the TX. Pull out the misc plastic pieces that hold in the fake 2 Antenna on the controller.

Located directly below the PCB at the top of the TX is a short DiPole Antenna, that has black Heat shrink over it hot glued into place. Carefully pry it out and desolder it.

Make note of which solder pad is the "Signal" and which is "Ground pad", the ground pad will have the braided shield wire while the "signal" wire is the center wire that the braided wire covers... If all this sounds confusing, it'll make sense when you see it .

I happened to have a dead TP-Link 2.4Ghz Router on hand that I scavenged the Antenna, SMA connector and pig-tail wire from. This router was state of the art in it's day and had three 6" antenna on it... Although the length of the antenna aren't really a meaningful gauge, simply pulling the cheap internal antenna from a cheap wifi router, may actually be worse than just leaving the factory antenna in place.

Solder the pig-tail wire in the same config as the original, drill a hole for the SMA connector, bolt it down, glue if you can't get it secure (cramped quarters even for a mini wrench) and mount the antenna BEFORE installing batteries.

The Antenna acts as an impedance matched "Load" for the TX's final amplifier, if the Antenna is not present when powered up there is a real risk of cooking the TX's output stage.

On the Drone's Side, I opted to simply re-position the internal Antenna (qty 2) outside the body of the drone. From the factory, the Antenna are located in the front Arms and laid right along side the front motor ESC'S (Electronic Speed Controls)...

Certainly I can appreciate that the manufacturer wants a sleek, streamlined product that is not a Porcupine of a monstrosity, but "Come On!?!" right along side of the noisiest of electrical components... Why not introduce a sacrificial Brushed motor inside there as well to see just how poor the reception can really be???

Carefully pull out the Antenna, poke a couple of hole just behind the frond Landing gear mounts, feed the 2 Antenna thru the holes and re-assemble.

Once the landing gear/legs are in place, I opted to simply tape them onto the outer surface of the legs.

Of note may be that the Antenna in both the upgraded TX/Controller and the drone send/recv are positioned along the same plane. in this case vertical, while their original orientation was along the Horizontal plane. I can't say which orientation is "Better", but that they should both agree ie; match...

The video below is of the finished Mod, tested out to 2.35Km!!! The range was tested between the Video and Google maps 3 (three) times just to be sure that it was in fact the case. AND that's not the Max Range! That's simply the range of the Batteries to fly out and back with a bit of reserve should a head wind come up on return.

HS700 Ant Mod w Range test 2Km plus (8 min 5 sec)
Last edited by Rural Flyer; Dec 02, 2018 at 02:42 PM.
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Jan 12, 2019, 09:01 AM
Registered User

Holy stone HS 700

Nice Video, i also would try it in the next week, but now i have some problems with my HS 700. Callibration not possible, the drone dont start, the first 8 flights are very good in combination with a gopro 4, but since 3 days, no start possible. The ledīs blinkend alternatly green , i have try it very often, fond no gps signals, and when i try to start manually without gps, the same -no reaction

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