Airtronics M8 and JR reciver?

Here is some info I found:

http://rchelibase.com/radiofaq/

What transmitters and receivers work together?

Pulse sequencing - Although I know of no valid reason, manufactures have chosen to differ in the position for which channels are placed in the encoded serial output. The stick pot you connect to the encoder channel 1 input defines the function of the first channel. Any stick pot could be connected to any input.

Futaba and Hitec use a sequence of aileron, elevator, throttle, rudder. JR selected throttle, aileron, elevator, rudder. While Airtronics chose to send elevator, aileron, throttle, rudder.

On AM modulation all transmitters will operate all receivers, and if you wanted to use a Futaba receiver with a JR transmitter you would just have to remember that you plug the servo’s into the receiver based on the transmitter sequence and not the receiver definition. The receiver does not care which control is on what output.

Now on FM we have a different story. Manufactures have chosen not only to rearrange the pulse sequence but to also select opposite high/low frequency shifts.

Positive vs. Negative Shift: When working in FM mode, Futaba and Hitec are compatible, and JR and Airtronics are compatible. This is because of the way that each has chosen to implement the frequency shift to represent a data bit. One has selected to send the lower frequency normally and shift to the higher frequency to represent a data pulse, while the other sends the higher frequency normally and shifts to the lower frequency to represent a data bit. Both Airtronics and Hitec now offer a transmitter where you can select the shift mode that means that they can be set to work with either brand receiver.

JR and Airtronics are compatible xmitter to receiver, and Futaba and Hitec are compatible. What this means is that a JR receiver will work with an Airtronics transmitter and vise versa if you remember to plug the receiver according to the transmitter sequence. Hitec also make a positive shift receiver compatible with JR and Airtronics. They also make a shift selectable receiver that can be used with all transmitters.

Futaba and Hitec are also compatible using the same rules.

If you do choose to operate one manufactures receiver on another manufacturers transmitter, be sure to range test the combination before use.

As long as the crystals match and the modulation type match you should be good to go. The information DL posted above accounts for some inconsistencies in compatibility, but what you described above (the "will do nothing" portion) is accounted for by the fact that your crystals are different. Note, you can use whatever crystals (as long as they are in the 75MHz band) in both receiver and transmitter. So get your hands on another 75.810 or 75.870 crystal and give it a try.

SKY, I have a pair of JR 75.870 crystals that I tried to use. They are FM and on 75MHz. When I plug the TX crystal into the transmitter, the little red LED light doesn't come on, but when I put the one airtronics crystal into the transmitter, the light comes on. I'm talking about the LED on the M8. I think the crystals have to be Airtronic and compatialbe with the RF Module.

So, if I purchase a pair of airtonic crystals that match the RF Module on the M8, should it work?

If the RF module is not crystal based, then yes, you need to buy a crystal for the RX that matches the RF module. If that does not work, then the issue is beyond what I can tell you without seeing the equipment.

Do you know what channel the RF module is?

The Rf Module has a sticker on it for channel 84.

Then you need a 75.870MHz crystals (which you stated that you have). I'd try and get a set of Airtronics crystals in that frequency and give it a try. If it still doesn't work, you may need a new module...or a new TX/RX set up.

Despite what the picture shows, here's a set at TowerHobbies: CLICK HERE

Well I missed up with my post earlier, the JR crystals that I have is channel 81, which is 75.810 and not the 75.870, and nothing happens when I try them in the M8. So, I guessing I need Airtronic crystals?

Thanks SKY.

Or a pair of 75.870 crystals. TO be on the safe side and not waste money, I'd go with the Airtronics crystals. Technically it shouldn't matter what brand crystal as a crystal is a crystal is a crystal...but I can not count the number of times someone has proven that to be untrue.

I provided a link to a set of Airtronics Ch84 crystals found on Tower in my previous post.

Go for it, and let me know how it works out.

Re-reading what I put and Sky said, I think your radio is fixed to whatever frequency the module is (75.870). So you need to get an airtronics receiver crystal on that same frequency. Then I think the JR receiver will work for you.

RCboyz has some airtronics crystals $13 but they are an off-brand and it states that they don't work w/ the M8. So make sure you don't scoop them up. I think you need to use the genuine Airtronics brand.

UNCD, get a Novak XXtra synthesized reciever. it eliminates rx crystals and works with all transmitters.