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Can 4ch Tx Slave for 6ch Master?

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Old 08-14-2003, 07:34 PM
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chall
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Default Can 4ch Tx Slave for 6ch Master?

I was trying to make an old 4-channel Futaba be a Buddy Box to a 6-channel Airtronics.

I felt like I almost had it. Using info on the web I used a software oscilloscope to see the pulses, find the right pins, etc.

But it never worked. Can a 6-channel receiver just not handle a 4-channel pulse sequence? Or was it just some other more subtle incompatibility?

Thanks.
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Old 08-14-2003, 07:50 PM
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Default Can 4ch Tx Slave for 6ch Master?

I think it is more of a futaba airtronics compatibility problem. I use a 4 ch futaba as a buddy to a 6 ch futaba all the time. I don't think you can mix those two brands though. I don't remember what the shift is on them, but I think they may be opposite? One of the radio gurus will have to let us know for sure though.
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Old 08-17-2003, 11:36 AM
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Default Can 4ch Tx Slave for 6ch Master?

Thanks FlyBoy. Every clue helps!
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Old 08-17-2003, 12:19 PM
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Default Can 4ch Tx Slave for 6ch Master?

Hi Chall,

According to what I read from you, you found the PPM-OUT-signal on your slave Futaba TX. Check with the scope if it's a positive or negative pulse. Check on your Airtronics master TX for the PPM OUT-signal. It should be of the same type as the OUT-signal of your slave. If it's reversed compared to your slave TX, then you should reverse your slave signal.
Contact me eventually via the E-mail addres mentioned in my website. Perhaps we can sort it out...
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Old 08-18-2003, 01:52 AM
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chall
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Default Can 4ch Tx Slave for 6ch Master?

Ahhh, Olivier, your site is excellent. I was using it all along. I used the software oscilloscope you recommended, the Russian one. I had an inverter circuit, and I tried both with and without it. It was hard for me to tell what I was looking at, but there seemed to be more pulses than channels. Something like 7 pulses for the six channel and 5 pulses for the four channel.

If you're really curious, I can get it set up again and try to capture the pulses with a screen capture program.

I went ahead and found a second Airtronics transmitter on eBay to use for flight training; but I'd be delighted to try the Futaba again if you think we might learn something useful for your website!
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Old 08-19-2003, 03:25 PM
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Default Can 4ch Tx Slave for 6ch Master?

Hi Chall,

I lost (read "delete") your message and thus also your E-mail addres...
Contact me again on the E-mail addres mentioned in my website.

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Old 08-19-2003, 04:50 PM
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chall
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Default Can 4ch Tx Slave for 6ch Master?

My email is chall@rtpnet.org

I'll try to email you as well.

Thanks!
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Old 09-06-2003, 02:59 PM
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Default Can 4ch Tx Slave for 6ch Master?

Hi Charles,

Sorry for the delay in answering.

Whatever does not work, it is quite possible you find 7 pulses on a six channel radio or 5 pulses on a 4 channel radio. In fact the manufacturer is then just not telling that the radio has one or more channels, it's just hidden and not used.
This is the case with the popular Futaba Skysport 4, which can rather easily be transformed to obtain a fifth channel (see here .

This should in any case not be of any importance for buddy box compatibility.

I would be delighted if you could send me a screen capture of the OUT-signal of an Airtronic transmitter (or both of yours) : at last I would know if Airtronics use a positive or negative PPM.

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