Hey all,
The FrSky hack module and receivers are now getting alot of attention - and rightly so - they are awesome!
I've converted a few transmitters using them now and, like others, have had no problems.
** before I begin, some people have asked why not just use a plugin module from Corona, Spektrum,etc **
Good question. The answer is that Corona's build quality is questionable and there are enough bad reports out there that I wouldnt touch them. Spektrum are great, but you are paying for all the "module" plastic casing and electronics. At the cost of £60 upwards for a good module, vs £15 for the FrSky Hack module, its an easy decision.
Also, any module that sticks your aerial out the back of the transmitter has got to be bad design - if the transmitter falls over, it falls on the aerial housing snapping it off. Ive seen loads of these unfortunately.
And lastly, why would you want two aerials?! Even the old 40Mhz aerial is going to suck in just a bit of your new 2.4Ghz signal; and I think its better to have every little Hz of power used in controlling my car, not in bouncing off my old superflous aerial.
So, here is my KO Esprit II FrSky in all its glory:
So, first thing to do with your old 40Hz radio is unplug the existing module, unscrew the old aerial then carefully open up the transmitter and fully remove the aerial.
N.B. watch for the battery connection cable as it will most likely be attached to the back panel of your transmitter, so when you take it off, unplug the battery connector from the daughter board it to avoid damage.
So, assuming you have got all the 40Mhz gubbins out of there, you now have a clean transmitter waiting for the new module.
First thing I do is to use my Dremel with 10mm rotary sanding drum to ream out the existing aerial hole to just over 10mm.
EDIT -- 6th March 2012 -- just fitted another 2 of these systems, and I found that there seems to be a difference in tolerances on these 2.4Ghz aerials, so actually you get a safer build if you drill out the aerial hole to 9.5mm first, then using your sanding drum and/or circular hand file, carefully ream out the hole to the required diameter. Remember, keep offering up the new aerial to ensure a nice tight fit. It may actually end up being just shy of the 10mm as one of mine was tonight.
Offer up the new 2.4Ghz aerial into this reamed out hole. It should push in with a bit of force at the knurled end point. If done right, this will simply be a resistance fit and should be very secure; requiring no additional glues or adhesives.
Ensure the new aerial can bend and rotate as designed.
Now, to install the actual module, first choose where you want to place it.
For this KO, I cant think of anywhere better than in the old 40Mhz module casing, so im going to choose there.
I have seen alot of people squeeze them into the top part of the transmitter where there is some empty space, but that leaves you no room for the BIND button and LED daughter board - and you'll see why I think this should go here later on.
It also is a pretty tight fit and at very best, awkward. If a component or button fails in your transmitter, fixing it is going to be much harder when you have to work around or temporarily remove your FrSky module board; or if you want to expand your new FrSky system to include telemetry or other nice things like that, you wont have the space up here to do so.
So, im sticking with it in the 40Mhz module casing.
First thing to do here is to remove the existing 40Mhz board.
Simply unscrew the 3 screws that hold it in place and gently lift away - in some cases there might be glue that needs carefully cut with a craft knife.
Stick the 40Mhz board and crystals on a classified site and make some money back
Because I wanted some flexibility to upgrade at a later date, I didnt want to use hot glue to mount the FrSky module inside the case, so instead I actually went for Lee Martins excellent servo tape. Its as sticky as Sticky the stick insect on a sticky........ you get the idea
Holds it firmly, but can be removed later with no cutting if required.
Now, thats the aerial in, and the module in place.
Next, before you solder up the connections, I think its a good idea to mount the daughter board for the BIND button and LED.
This is where loads of people disagree, but I stronlgy recommend that you drill your transmitter housing. Its a much more professional, tidy finish; and I disagree with those who say that you dont need to BIND more than once or look at the LED. Both are there for a reason.
- the BIND LED actually serves three functions.
yellow/orange = normal use, and shows that your FrSky module is 100% working
flashing red = BIND mode
solid green = "Range Check" mode
If you cant see this LED because you have buried it in the old 40Mhz casing as Ive seen some people do, then its alot more difficult to be sure whats happening - eg. are you in BIND mode or not?
Also, the BIND button is so straight forward to use that its great. Burying it inside the transmitter means this becomes much more of a task.
I dont know about you, but Ive had interference at races before, even 2.4Ghz, and 99% of the time, re-binding solves these as the TX/RX jump onto a new portion of the 2.4Ghz spectrum.
If the BIND button is hidden, this 5 second job becomes a bit more of a nuisance.
Some people have also drilled the front of their transmitters, but this puts the LED right through the nice KO Esprit name plate. Yuk! Not a nice solution.
Its just my opinion, but better to take the time and do it right.
You can see from the photos where I have placed the button. There is just a perfect amount of space in front of the aerial, and it all looks very nice and is immediately visible when needed.
To do this, measure the distance between the button and the LED centres, then translate this onto the desired location on your transmitter.
The button is a 3.5mm hole
The LED is a 3mm hole
Get the Dremel out and drill them nice with a smooth action to prevent chipping of the plastic.
Once drilled, offer the daughter board up to make sure they sit correctly.
Its a good idea at this point to jsut try the button. If the fit is too tight, or your hand was a bit Shakin' Stevens when drilling then the button may foul on the edge and not give a nice "click" feel.
If all is well, then we want to mount the daughter board...
Again, I used the LMR servo tape for this one. It really is that good!
But maybe you would prefer a more secure hot glue solution.
With that in place, its time to solder up the main module board and we are done!
For this, you need to find the negative, the positive and the PPM rail.
On my KO Esprit II, its all very nicely provided on the left hand part of my board.
In order, from left to right, we have PPM, Positive, Negative.
I cut the wires on my FrSky module to expose about 5mm of bare wire, then tin them as normal.
Just before applying them to the board, I freshen up the solder on the board (simply heating up the PPM, +, - pins and adding a touch of new solder). Then offer up the FrSky wires and solder them on.
You shouldnt need any new solder at this point, just the heat from your iron should melt the solder that is already there and that should be plenty.
After soldering these on, make sure the joints are mechanically sound (ie. give 'em a yank and if they dont come off, should be good!)
Here is our example KO, ready to go:
Ensure the grey aerial wire is then screwed securely to the aerial itself; and you are done.
Good idea at this stage to power everything on and give it a test!
Bind it to your reciever and connect up a servo to test the controls.
If all is well, screw the transmitter back together, admire handiwork, stick on a brew and eat well earned digestive.
Proper job.
Hope it helps.
Andrew.