Walkera F4 FPV - UPGRADE your radio with a external antenna.

Walkera have been releasing cool new RTF - Ready To Fly - FPV "toys"   and radios with build in video screen for flying these FPV devices. the biggest problem.  particularly with the smaller versions, is the short reach of the video link.    FIX this by modifying the radio to use external video antennas.

In this post, I give basic instructions for upgrading the video antenna on your F4 or F7 FPV radio so you can fly further with clear video. 

Whats not to love about Walkeras direction here.  Clearly their RTF RC geeks are seeing the FPV light. lately they have released a broadside of close to cool - out of the box FPV stuff.!   and they are doing it right, in that their video downlink is FatShark compattible out of the box. Awesome.

To support their FPV direction they have released the F4 and F7 radios which both have a build in  5.8 RX (Reciever),   the catch to this is, the included antenna is a bit directional and not particularly good often mounted under your fingers.  

OTHER USES FOR THIS RADIO - I found a other use for the Walkera F4 radio, I fly multi-rotor for video use, and love the little screen i the F4,  so I put a Walkera RX601 6ch radio on the back of the brushless gimbal and give the camera operator the F4 to fly the gimbal. Naturally use a ImmersionRC video TX or the radio part of a TX5805 for the video downlink to your F4 gimbal control.

My biggest gribes with the Walkera radios is 3 things.  
1. BLUE SCREEN.. if you fly too far away, instead of snow you get blue..  walkera need to fix this.
2. Please please Please.. include a SD card recorder in the radio.. so I have one less thing to fiddle with.
3. Antenna.. I need a external antenna plug.. but hey, that last thing we can fix. and it is really easy.

You will need:
Walkera F4 or F7 radio
IPX / u.fl to SMA antenna cable  
Some kind of cool antenna.  More on that later.
Cup of Coffee or maybe a cold can of soda. 

Tools 2mm allen wrench and small phillips screw-driver  
A small lid to put the screws and not loose them.

 OK Ready.

START by flipping your radio over face down.

Use the 2mm allen to remove the 4 screws, one in each corner.

Then use the philips screwdriver to release the screw on the backside of the antenna cover.

Yank a bit on the antenna cover, it will release (AFTER you remove the screw) 

After removing the antenna cover, there is one more allen screw to remove.

Notice the thing holding the antenna cover and the 2.4g antenna in place. you will need to put that thing back in

Next use a flat screw-driver to prey away the rubber cover on the sides of the radio. you only have to pull the rubber out on the back-side edge.   

Now you can pull the backside out and open it like a clam. the red arrow show the build in antenna.


Next use a flat screw-driver GENTLY - or a pair of bend needle nose plyers - to GENTLY releast the IPX plug from the Video Reciever.  (did I meantion GENTLY)

No reason to remove the build-in antenna, I tucked the cable from it under the antenna wire and taped it in place for good measure.

Next it is time to prepare the hole on the shoulder of the radio for the SMA plug.  pull out the rubber plug first.  The antenna plug is a "smidge" too large, so I grabbed a drill and used it by hand to gently twist and remove just enough material for the plug to fit perfectly.  Next, use a knife or pair of small side cutters to cut away a little of the material behind the hole so the plug can fit all the way to the hole. Push the plug through and faster the nut on the outside.  tighten the nut appropiately. Remember this is not a lug on your cars wheels.

Finally, massage the IPX plug onto the plug on the video reciever.  be gentel but firm, its not as easy as you think, and you don't want to break anything in the process. 

DONE.  congratulations. you now have a external VIDEO antenna mount on your radio.  Only thing left to do is to button it all back up.  

Antennas, so now basically you have disconnected the build-in antenna, so you will always need a antenna mounted on the external plug if you want to recieve video to the F4 or F7 radio.

If you fly a stock  TX5805  radio, you can simply use any straight 5.8 antenna, to recieve the signal from the straight antenna on the TX5805,  the range improve if you arrange both antennas so they are vertical.

If you have installed a SpiroNET antenna you can put eiter another Spironet antenna on the F4 or F7,  make sure both antennas are horisontally level when flying.  note the antenna may be upside down if that is easier.

With a SpiroNET antenna on the TX5805, you can get creative with your reciever antenna and here is a picture of my F4 with a 7-turn Helical from Circular Wireless, the 7 turn give me 15db db signal amplification.  This is enough to fly FAR FAR out of visual range for your micro multirotor.   But the antenna have only a 30 degree "cone" of coverage, so you will need to act as the antenna tracker and keep pointing the antenna by moving the radio to have a perfect video reception.  Helical's with less turns have a wider "cone"  and "Cross Hair" antennas have a even wider "cone".

BTW. if you do land out.  the helical antanna can be used to triangulate your aircraft.  rotate round 360 and point the antenna to see what direction you landed in.  start walking.  continue to check the direction until you find the source of the signal.

Happy Flying.

 

 

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Comments

[Bo Lorentzen]

Hey lao, Well if you are looking for every bit of a edge you can get, I would go for the 2s 1500mah 35-70c as the higher C value means they will maintain voltage longer (maybe another minute or so)

[lao]

Thanks Bo,

I was looking for a 1500 mah,

which one is the best compromise here:

http://hobbyking.com/hobbyking/store/RC_PRODUCT_SEARCH.asp?strSearch=Turnigy+nano-tech+1500mah+2S+2

Thanks again ( sorry, i m asking too many questions :()

[Bo Lorentzen]

Hey lao, welllllll good question. bottom line, you can't haul a whole not more with the Horten-X without it starting to fly like a brick. you may be able to use some tuningly 2s 1500mah's the most. (I seem to recall the stock ones are 1000mah)

[lao]

Hello Bo,

Thanks again for the reply.

I got a last question regarding batteries.

Which batterie i could use to increase flight time?

I can remove the battery holder and use rubber bands, i don't care about the "look" :)

I got a light fpv kit on my hoten x and i have also removed canopy.

My fpv kit weight in total: 32grams

What's the max weight this quad can carry?

Thanks in advance

Regards

lao

[Bo Lorentzen]

Hey lao, yes technically speaking you can put a microphone on there, but honestly, I would avoid soldering the VTX, there is sound on the video you record with the Mobius.

[lao]

Hi Bo,

Thanks for the reply, i wont fly out of sight anyway.

I used google maps distance tool and, 300m is already "far", sound enough for me.

I have a last question:

I want to connect a microphone to my vtx just to hear to motors sound. CAn i connect a electret microphone directly to vtx sound input without using a amplifier?

there's the microphone:
http://reviseomatic.org/help/e-components/Electret-mic.jpg

thank you

[Bo Lorentzen]

Hey lao, basically stay close, keep in mind most quads are not really made for more than 1000m, in terms of flight time and getting back on the same battery. ultimately you need to do a range-test to validate what you have obtained from the modification. before you fly out of range.

[Bo Lorentzen]

Hey johnny, Yes I have tested the RX706 with the F4 and it works, obviously its not a 7ch radio so you don't get the full value. :-)

This is where I got the RX706 http://walkerahelicoptersupply.com/collections/qr-x800-parts/products/qr-x800-z-59-receiver-devo-rx-706

[lao]

Thanks Bo,

I will put a external 2.4ghz as i did for the devof4 vrx mod.

Do you have an idea of what the max safe range i can get with a devo f4?

Since i started fpv, i m really tempted to fly further, but i m scared by losing the tx signal.

[johnny]

Did you test this rx706 with F4 personaly? they are hard to find a RX706... Do you know more Devo receivers with ppm?

[Bo Lorentzen]

Hey Johnny, yes you could use the F4, You can use the Walkera RX706 for PPM out. Plug the cable into the data-bus port.
That said, I would consider a Devo7 because then you also have channels for the flight-modes ;-)
*also you really can not fly a FPV mini-quad with the build in screen, you need goggles to really see what is going on .

[johnny]

Can I use this F4 with a blackout mini H quad using naze32?
If so is there also a ppm receiver from walkera?

[Bo Lorentzen]

Hey lao, I love the Hoten-X its just a friendly aircraft. easy to get along with and easy to fly.

OK the low-down on the F4 is.. its not really the F4 thats the problem.. its the little antenna on the Hoten-X which frequently is hidden by the body of the Hoten-X
but you can help it.. if you buy a directional antenna and mount it on the F4, so it project its signal power to the aircraft. that will keep more signal on the antenna.

[lao]

Hi Bo,

I m flying a ... Hoten x, not really the latest must have drone, but it's a really good fpv plateform.

I finally bought the HK qanum v2 and a RC832 receiver with cloverleaf antennas.

I got a 600 tvl 1177 camera and a 200mx video tx from eachine.

TX:
http://www.hobbyrc.co.uk/eachine-et200-58ghz-32ch-200mw-video-transmitter-rp-sma

Camera:
http://www.hobbyrc.co.uk/hs1177-plastic-cased-mini-board-camera-sony-super-had-ccd-with-600tvl-ir-blocked

the fpv system wights 22 grams withe wires.
I fly it really far, but i don't trust the devo f
4 regarding the range, so i m thinking to mod it if it's doable.

[Bo Lorentzen]

Hey Lao, Yes technically speaking you can do that. Im not sure what you are flying, but keep in mind that typically the biggest problem is the video range, the control range typically go further than the video.

[lao]

Hey Bo,

Thanks for the reply.

I mean the remote control 2.4ghz antenna, i have already do this one for the 5.8 ghz video signal.

Can i use this antenna for the 2.4ghz antenna mod: http://www.banggood.com/Wholesale-Dual-Band-2_4-or-5_8Ghz-6dBi-RP-SMA-Omni-Directional-Wireless-WiFi-Router-Antennas-p-49578.html?p=YL2512105842201212FR
?

[Bo Lorentzen]

Hey Lao, yes you can use this mod for a Walkera F4 or F7 radio, to increase the range I suggest a 5+ turn helical antenna.

[lao]

Hi BO,

Can i use this mod for the TX antenna?
and which antenna i could use to increase my tx range?

thanks in advance

[robi]

Thanks for the tuto ! :) A must have !