I have a Futaba T6exap that I would like to use with a Futaba T4yf as a buddy box. The T4yf is suppose to be set up as a buddy box only. the 4yf has no antenna, battery, or Xtl. Will this setup work together?

I have also observed that when the trainer switch is lifted on the t6exap I still have control with the 6exa. Is this correct?

One more thing the cord that came with the buddy box seems to have a Jr end and a Futaba pig tail. Dos this mean that I can use the t4yf buddy box with my Jr f400?

Those two Futaba boxes should work together, yes. The best cord to use would be a Futaba brand cord with the correct type of connectors on the ends.

I've had several cases at the field recently where guys were using simulator cords as buddy cords. For some reason, this didn't always work, though I don't know exactly why, since I don't have access to the pin out information of either.

When you flip the trainer switch, the master should NOT have any control of the plane, the buddy box should now have full control. If the master still has control, that usually means that the master is not properly reading the buddy box for some reason.

No battery, antenna, or crystal is normal and fine for Futaba buddy boxes. The master provides power through the cable, and reads the control position signals. The buddy box does not transmit, and it's RF circuit won't even have power, so no crystal needed.

JR buddy boxes do require their own battery, since JR cables do not transmit power from the master to the buddy box like Futaba does. JR/Horizon makes a cable that is designed to allow a futaba buddy box to work with a JR master, but it doesn't work the other way around, and it's rather annoying to use, since it doesn't provide power, which means the Futaba buddy box would have to have a battery and be switched "on", which would then cause it to transmit if it had a crystal in it.

You can buy the cord to work with different TXs, in my case I have the small square end for my TX and the round end with pins fro using with Hitec and Futaba. My TX is a Futaba 9-C and I have been using an older Hitec 7 for the box. The box dose not get the antenna pulled or turned on. It does show me the volts in it though?? Running the system does also draw a lot more juice out of my radio but it has more volts then is showing on the Hitec?? I set up one of my stunt planes with a box last week and tried it out yesterday. It's a lot of fun letting others try flying full stunt planes set up in ways they would never try. I'm going to set up a couple more on the box just so people can try flying different planes without any fear of crashing. Yesterday I taught a friend how to flat spin. After that he was spinning one of his own planes flight after flight. Don't know why I haven't done it sooner.

To add to what Montague said...

On a properly configured buddy box setup, there should be absolutely NO change in the position of the control surfaces or throttles when you flip the trainer switch and back.

In other words both the master and slave must have exactly the same trim settings.

You should also test this at all stick extremes too...

e.g. move the right stick left on both the slave and the master, then flip the switch... there should be no change in the surfaces, which would reflect a difference between the two TX's...

Yeah, that, I totally forgot to mention the centering/trim thing. If you have a plane that's been flown, then if you set up the buddy box that way, the plane will be nicely in trim. If it's a new plane, you will often benifit from a trim flight, then set up the buddy box.

However, you don't necessarily need to have the end points be the same.

My wife and I fly together a lot, we have my 9303 and her dx7 set up to buddy box a number of our planes, including my 50cc Extra, an electric GeeBee model Y, a Dragon Lady, and several others. We use slightly different setups on some of the planes, sometimes due to the radio (I have throttle curve on the 50cc gasser, she doesn't because the dx7 can't do that, instead I fake it with the subtrim), and the mixes are totally different as well. On the Dragon Lady, she likes a faster rolling rate than I do, but I have more elevator and less expo than she does because we like different elevator feels.

I also have another computer radio that I use with my 9303 on my LT-40 for intro flights and such. The buddy box (an old JR x347) is set up with more expo and less throw than what I have. I have enough throw on the LT-40 to do flat spins and all kinds of fun slips, flat turns, and other stupid trainer tricks, the x347, not so much, it's much more trainer-like.

So, you can use the fact that the buddy box and master TX use their own programming to good effect if you want, I do. Lots of fun.

Will the battery lights on the t4yf com on when attached to the t6exap if every is working correctly.

If the trainer cord is not attached to the 6exap and the trainer switch is lifted will the sticks on the t6exap still control the airplane?

I think I am trying to trouble shoot why things are not working.

This is the cord

Just checked my eclipse 7 and the trainer switch locks out the sticks even if there is no trainer cord but the Jr f400 dos not.

I don't know if the t4yf lights should come on, but I don't think they will.

If you don't have a battery in the t4yf, then the master has to provide power. I haven't seen futaba cords that had the phono jack in the middle that weren't from simulators, and I haven't see one work with Futaba gear like that. I could be wrong, but I think your problem is the cord.

If it's a power thing, then you might get it to work if you put a battery in the t4yf, leave the crystal out, and turn it on. Then try them two radios together.

That does look like the cord from my flight sim. My Futaba 9-C as the master will not work as a trainer TX unless I go into the radio and activate the trainer switch. If it isn't activated then it's my snap roll switch.

Ok I got a new trainer cord today. When plugged in the lights on the T4yf light up and I have control with the trainer switch lifted on the 6exas.

My next question will rate seating, end points and mixes set up on the computer radio be affected when control is switched to the non-computer Tx?

Gray Beard
What flight sim do you use this cord with?

Well, the computer radio's settings won't be affected, but they won't be in effect either. On most buddy box setups, all control is switched, it's as if you turned off one transmitter and turned on the other in the air. So if you set lower rates and expo and subtrims on a computer master, none of that will show up for the buddy box. This is usually backwards of what you'd want. So except in special cases, when you set up a trainer with a computer radio and a non-computer buddy box, you want to turn off all the rates, expo, subtrims, etc. everything to 0 or 100%. Then set up the plane the old fashion way, by adjusting the linkages on the airplane itself.

(one thing you can do is set the computer radio EPA to something higher than 100%, this gives the instructor more throw than the buddy box, which is useful).

Oh, if the plane has been trimmed out and flys straight and level hands off on the master, then you can trim the buddy box by making sure that nothing moves when you flip the switch back and forth. Do it at center to check the trim settings, then do it while holding both the master and buddy box sticks at full throw to make sure the buddy box doesn't have more throw than the master.

Ive been using close to the same set-up. Ive noticed the elevator was trimmed near the end on the master (6EXAP), but was just out of the trim range on the buddy box (T4VF). 125% EXAP trim vs 100% T4VF trim. Make sure the master box / plane is trimmed close to center.

Tomorrow is going to be my first time using a DX7 with the Futaba T4VF as a trainer box with a 46AX Superstar 40.

I couldn’t find a “square to square” Futaba buddy cord, so I found two of the “round to square”, cut & soldered them to make a square to square cord. As you might suspect, this didn’t work. Any comments or hints to make it work? If not, I'll just order the correct one.

I'm guessing there is something with the pinout going on there. I don't have a square-to-square cord, so I can't check with a meter, but I suspect there is a pair of wires that are crossed in the cable, and your straight through cable is causing the polarity to be reversed.

Thanks KirkI was careful to get all of the colored wires matched & checked continuity...still a mystery why it doesn't work...sent Futaba an email and the response was to buy the new cord....guess that's the solution.