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JR Radio buddy issues

Old 05-28-2021, 02:32 PM
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w6k
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Default JR Radio buddy issues

I have an XP7202 that works well and with the frequency synthsizer I can fly multiple models with it. I have numerous radios so have not upgraded to 2.4 yet. Right now I want to teach my 13 yr old grandson some R/C flying skilsl. I learned to fly the old try and crash method back several decades ago so have never used a buddy box. The 7202 has a buddy box feature and I bought the trainer cord and have it programmed. I selected the mode that only allows basic 4 controls with no switches for the slave. After reading on the forums I got the impression that any JR radio can serve as a slave. I have several Circus Hobbies simple 4x starter radios that I use to use for glider work. Each of these radios have different battery set ups and require retrofitting. The old Ni-Cads have been removed and I retrofitted a MAX 4 transmitter with a new high capacity Ni-MH and it lights up fine and the power meter is far right on the scale. The power light comes on when the trainer cord is inserted and that is normal, but transferring the control from the 7202 to the MAX 4 yields ziltch. No sign of life. The next radio I tried was a Century 7 which has lots of switchs and smooth gimbals.I used to use it before I got the 7202. The Century 7 has a different battery connector than the MAX 4 so I bought another 9.6 hi cap battery for it with the same negative result. I did read in one post that the Century 7 is a PCM radio although it says FM. The current receivers I have are PPM so that might explain the problem. Is the Century 7 really a PCM and if so why isn't it marked as such? The older MAX 4 is just marked FM and that should be PPM so why doesn't it work in trainer mode?
It could be that the 7202 has a transfer issue, but it is working fine on the foam trainer plane I have. What am I overlooking? Should any JR radio work as a slave? Can you slave a PCM to a PPM?
Old 05-30-2021, 04:44 PM
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w6k
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Since there are no responces let me ask this. Does the slave trransmitter have to be on the same frequency as the master?
Old 06-03-2021, 09:18 AM
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The answer is no to the above I learned by reading. I would like to hear from anyone who has successfully used a buddy box with a JR radio.and what radios were used.
My xp7202 will work as a buddy box by changing a menu item to slave ,but I want to use it as the Master. So far the two older JRs with no menu that I tried will not work as slaves, but both have a trainer switch and will work as a masters. I am thinking that any transmitter with a trainer switch that does not have a way to change to a slave, will only work as a master, but I don't know that for sure. What has been the experience of others?
Old 06-03-2021, 03:01 PM
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The manual for the XP7202 I found on-line seems to imply that it can only be used with a 7202. You're talkin' 80's-90's vintage radios, and back then there was very, very little commonality between them, even within the same brand. Throw very different generations into the mix, and your quest is likely futile. Akin to the issues we used to have with servo connectors, even within the same brand....
Best to hunt down another 7202 to use with the 7202, or perhaps a MAX 4 for the MAX 4 (if it can buddy box at all - I haven't looked that one up).
Old 06-03-2021, 03:44 PM
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AWorrest
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The Century 7 and Max 4 were out before I switched to JR. The earliest experience I had with JR was the X347 transmitter. I’ve owned a number of later JR transmitters. I suspect any transmitter of later vintage will work either as a master or as a slave. Two things you should be sure of. The slave transmitter modulation has to be set as PPM/FM. The master transmitter transmitting modulation is not a factor as its DSC output is always PPM.*

The other thing to check is the trainer cord. Check it out with an ohm meter. Make sure the inner conductor of one plug is connected to the inner conductor of the other. Same with the outer conductor. I had a cord go bad without showing any visible sign of a problem.

Allan

*This would be true if restricted to the trainer function. I’m not sure what the DSC signal is if it used to drive a PCM receiver and servos with the RF turned-off.

Last edited by AWorrest; 06-04-2021 at 02:39 PM. Reason: added qualifier
Old 06-03-2021, 04:25 PM
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w6k
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All my stuff is old just like I am! Both the MAX 4 and Century VII work as Masters and the trainer switch will transfer the input to the XP7202, but for some reason neither one will work as a slave. Another XP7202 would solve the problem and they are upgradabbe to the newer 2.4 Gig with a different RF module. I will look around for a 7202. The trainer cord is brand new and I did check the continuity. As you say, it appears to be incompatability.
Old 06-04-2021, 02:32 PM
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AWorrest
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I doubt that the XP7207 will only work with another XP7207 as a trainer. If that is the case, it would make the 7207 an unusual JR product. Previous transmitters such as the X347 and X388S state in their manuals, “The Slave transmitter must be PPM (Pulse Position Modulation) with a DSC (Direct Servo Connection) jack. If the Slave transmitter is PPM/PCM selectable, select PPM. The Master transmitter may be PCM or PPM.”

I have an XP9303 which is about the same vintage as your 7207. Last night I programmed it as a Master transmitter to one of the newest JR transmitters. Before purchasing another 7207, you should see if you can borrow a JR transmitter newer than the 7207 to be used as a slave. It is as likely that the problem is with the MAX4 or Century7 being used as slaves as it is for the 7207 being used as the master. Not having any access to their manuals, I can’t comment further. I wish I could see how the MAX4 and Century7 are to be set up as slaves.

The only problems I can see in setting up the 7207 programmed as a master are some simple oversights. Make sure the 7207 is set to P-LINK, not SLAVE/P-LINK. Either rocker switch can be used as the trainer switch. Make sure you are using the correct one.

Attached is the page out of the X388S manual on setting up the trainer condition. It and the X347 were being marketed at the same time as the MAX series was. I have a brochure from Horizon describing both. This definitely places the X388S before the XP7207! Although the navigation through the menus differ for the transmitters, it offers a better description of setting up the trainer than does the 7207 manual.

Allan
Attached Files
File Type: pdf
7207 Problem.pdf (164.1 KB, 4 views)

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