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DIY 2.4Ghz Radio Upgrade

fliteadmin

Administrator
Staff member
Admin
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#1

In this episode we dive into an old Futaba 72mHz transmitter to give it new life! Watch as Josh, Josh and David summarize what it takes to do this. Afterwards, if you feel motivated, you can dig out your old transmitter to start hacking, drilling, and soldering with David's how-to tutorial below. And if you're still looking for more, we added a link to Paul Bitmatta's step-by-step video below that!


<strong>Guide Written By:</strong>


David Windestal:


Got an old 72MHz radio laying around not being used? Or your looking to have a system with cheaper&nbsp;receivers?&nbsp;Then you've come to the right place. You can with easily and&nbsp;inexpensively replace or add another 2.4ghz system to your radio. In this guide we are going to add a FrSky DHT 8ch DIY Telemetry Compatible&nbsp;Transmitter Module to a Futaba 7C 72Mhz radio.





We're also going to make it possible to toggle between the 72MHz and 2.4GHz modules with the flip of a switch. No need to throw out those excellent 72MHz receivers to use 2.4GHz.


First I took of the back cover and drilled two holes, one for the&nbsp;2.4GHz antenna and one for the 72MHz/2.4GHz toggle switch, in the top of the case.


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Next I drilled a hole for the in the back cover into the battery compartment.


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The FrSky module comes with a toggle switch to select between 1 way&nbsp;communication (to be able to use the first generation FrSky receivers), 2 way communication (for the newer telemetry receivers) and firmware upgrade mode.


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I wanted this switch easily accessible but yet protected, hence the placement inside of the battery compartment.


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The module also comes with a bind button and indication LED. I decided to place these in the battery compartment as well.


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Now it's time for the electrical bit. You need to find out where the PPM output is in your transmitter. If you have no idea what I'm talking about search for mr Google for "PPM hack module '+your transmitter'" and you should be able to find it. In nearly all transmitters the transmitter module is separate from the main transmitter PCB. One of the cables between those two PCB's is the PPM&nbsp;signal wire.


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In the Futaba 7C these three wires are VCC, GND and PPM:


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For some odd reason futaba doesn't like to follow the standard coloring code for wires, so VCC is brown, GND is red and PPM is black. The FrSky module follows the standard though and has VCC as red, GND as black and PPM as yellow.


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To switch between the 72MHz module and the FrSky 2.4GHz module I added a simple 2 way switch. All it does is shifts the VCC (+) between the two modules. This way only one module is powered up at any given time, which saves battery and decreases the chance for interference.


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Here is a simple wiring diagram:


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All cables soldered up.


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Always insulate you exposed ends of cables! Use heat-shrink if you have any.


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Antenna and toggle switch installed in the top of the case.


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Find a good place to install the FrSky module. In the 7C there is&nbsp;plenty of space underneath the 72MHz antenna. I simply used double sided sticky tape to hold it in place.


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Reassemble the transmitter and you're done!


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Now you can use both your old 72MHz receivers and your new 2.4GHz FrSky receivers without having to buy a new expensive radio. The FrSky system is a frequency hopping system and very resilient to interference. The range is excellent. The receivers have excellent low voltage performance. Reboot time is really fast. The fail-safe is easy to set. It's easy to bind and the link-up is really quick. And on top of all that it's a&nbsp;really cheap system! If you're looking for a good cheap system this is the one to get.


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<strong>Additional video provided by:</strong>


Paul Bitmatta


AKA:&nbsp;bmsweb (Flite Test Forum Member)...


This is a quick run down on installing the a FrSky Module upgrade for the Turnigy 9x Radio. This kit also works with 2-way telemetry Receivers.<br>
The main reason for this upgrade is longer range, reliability and RSSI ideal for FPV applications.


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http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=17205&amp;aff=460671


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Klonas

Senior Member
#2
I thought this will be purely an educational episode, but wow, I had a smile all the way through the video. Funny faces :D:D:D
Also, cool that you've mentioned Turnigy 9x (even though the wire must be cut. NOOOOOOO).
I also had confidence in the Gumby. Just because it looks rediculous... Most of the good trainers do :)
And nice Transmitter Josh S. I wonder why is the antenna so long? Is it because of the frequency?
 

ananas1301

Crazy flyer/crasher :D
#4
I thought that the most funny thing part of the show is that JB got to do the end and not JS.

Unfortunately I don´t have any old radios...

Great episode :)
 
#5
Great Episode... I about died laughing when Josh Scott pulled up a single stick controller to modify... That unit is old.. I really wonder if you could upgrade that one :) Not that I would want to... I got into the hobby late and started with the 2.4, but this was still a quite educational episode and thoroughly enjoyed it.
 
#8
Idea for Bixler... Fly a plane (any plane) with that Single Stick Controller. There are a lot of younger people who have never seen one in use. Maybe it can be done in one of the 60 second quick videos.
 
#10
That Kraft radio is a collectors item, a museum piece!
Yes, I know. I had a friend who had one and that was the ONLY radio that he used. Just seemed like a nice collectable item to show off to people to show how nice we have it now, vs the yesterday. There was also a system of a push button, push once for one direction and twice for the other direction. I think a lot of people called it a clicker.
 
#11
I have seen those old Kraft radios fetch a lot of money. I think there are several who have modded them with updated output boards. Back in the day when I first started Kraft was the radio to have. I still get some feelings of envy when I see those light colored servos!
 
#12
We used to have single stick radios at my former club. I wish there were singlestick options available today as they are really cool.

//UndCon
 

fred0000

Senior Member
#14
not directly related to the main focus of the epesode but, you show that you are using a 800mah 3s lipo to power this radio, I had a 900mah 3s lipo on hand that i'd never use for anything else (have 8 of the same, this on was just an odd man out) so I am using it to power my Turnigy 9X, how long is this battery lasting for you in this radio?
thanks.
 

bicyclemonkey

Flying Derp
Mentor
#15
I've read that the 9x only needs 6v but I've seen both 2s and 3s lipos used in the Turnigy 9x. Is there a reason for one over the other? Something about the extra voltage being wasted as heat or something.
 

colorex

Rotor Riot!
Mentor
#16
I'd like to know this as well as my Tx NiCad runs out pretty quickly. It's a 9.6v 600mAh pack. It would be enough for my Bixler with 1300mAh on it, but not if I get 4x 2200mAh.
 

lobstermash

Propaganda machine
Mentor
#18
not directly related to the main focus of the epesode but, you show that you are using a 800mah 3s lipo to power this radio, I had a 900mah 3s lipo on hand that i'd never use for anything else (have 8 of the same, this on was just an odd man out) so I am using it to power my Turnigy 9X, how long is this battery lasting for you in this radio?
thanks.
I'm using a 2650 1C 3s in my 9x. It uses about 200mA/hour (with backlight). Leaving 20-30% of the charge in there, you'll get at least 3 hours of use. BUT, high discharge batteries do lose some charge naturally. I'd be charging the battery every couple of weeks regardless of actual use (obviously more frequently if you're running the battery down through constant use).
 
#20
lipo battery

Does anyone know what the lipo what was used in Josh,s futaba TCS as I've done the frisky 2.4ghz conversion now I can't get the original
Battery in. Sorry raising an old post but can't find any more info

Thanks
Daywalker