I was trying to use the cable that came with Realflight 3.5 for a buddy box cord between my Futaba 7C and my Futaba T4YF 72mh radio. I can get it to work with the power turned on the 4 channel (antenna and crystal removed). Will it work like this? If I got a true trainer cable, would it power the 4 channel radio also? In the 7C manual it doesnt say anything about having to power on the slave, and when I was training, I never powered on the slave either.

i have the same tx (7c, 4yf) but a g4 system. guessing the plugs are the same
your 7c has to be in the trainer mode to work (menu, scroll up, and click trainer. have to stay in that mode while useing)
the cord only works one way (the end with the adapter, has to be on the buddy box)
your other transmitter (buddybox) has to be on. cause the cord wont suppport the power function

try that and it should work just fine (works for me)

o btw make sure your buddybox has all the reverses set to normal (not reversed)

go fly

A couple things with Futaba and buddy box setups. First, the Transmitting box has to have the trainer function enabled. If you go through you manual and look for the trainer, if the sitch shows INH, the buddy box isn't going to work. Change the function so the switch shows OFF and if the transmitting box switch is thrown it will show ON.

The Buddy box must be in PPM Mode. The Buddy box should remain powered off, the power is supplyed by transmitting box. There is no need to remove the antenna and Xtal in the buddy box, they don't work when setup as the buddy box, only the gimbles work.

Some Futaba TX's will not allow Expo and end points to work with a buddy box, only raw gimble input. My 9C does allow the expo and end points to work on all but the throttle. My son's 6eax 72mhz just transmits the raw gimble movements of the buddy box TX without modification. What a susprise that was, and this was conformed by Bax last fall. I don't know if the 2.4ghz 6Eax works the same. No test bed to work with.

Your experience with not powering on the trainer box is correct. The power is supplied to the trainer box, but not RF capibility.

My suggestion is to get a Futaba cord that matches your setup. Set the transmiting TX up correctly and all will be as well as the mix allows.

Don

As Campgems said is good advice
Personally I have a LT40 with a Four channel non computer radio and a identical slave transmitter. This works without complication when I want to put someone on the buddy box.

something else I just learned the other day....the 7C will not show on when the trainer switch is held on if the buddy box or cord is bad......

I'm not the first to say it, but spend the few dollars and get the right cord. One day you will be in a hurry, hook it up wrong, and it will cost you the plane.

David

doubt it, it just wont work, the 7c will still be in control, but the 4yf wont work
if you will be buddy boxing a lot might be worth the money to get a better cord
the realflight one will work fine though, just test it before you go up