Parallel Interface for Futaba 4VF - Problems of unsteady signal / Transmitter off

[Daniel Manzato]

Hi All,

I've built a parallel interface for my Futaba Skysport 4VF using the transistor scheme (1 transistor + 2 resistors). Firstly it didn't work, but I got some tips here and found out that i had to disable the sharing irq of my SB16 emulation (I got a SB Live). After then, my interface started working, but with an unsteady signal, in another words it seems that I'm flying in a very windy day. I have already tried to choose another irq for my parallel port, but things only got worse. Another interesting point is that the sound of the plane is awfull, tottaly "gapped" and unstable, just like the commands of the transmitter. I was wondering if building the serial interface would solve these problems, but I would like to hear some suggestions here before anything.
Second, is it possible to use this interface without spending my transmitter battery? Do I have to stick the full antenna not to damage the transmitter?
*Any* help appreciated!
Thx!

PS: I'm using Win98 and FMS 2.0 Beta 6.

[bsergeev]

That's the problem with Futaba-s and parralel interface: they don't work together well.
You may either try a serial interface, which is much less jittery, or wait for Beta 7 release, which has supposedly better TX reading code.

[Daniel Manzato]

And is there some hope of Beta 7 release being released in a near future? Maybe I'd better start building the new cable...
What about using my transmitter turned off? Is there a way to save my battery of being discharged? If not, do I have to stick out the full antenna?
*thank you* !

[Steve Lewin]

The serial I/F will probably be better but Beta 7 is what you really need. It is definitely much better, no jitter and the planes can be trimmed. It should be out in the next few weeks according to Michael.

You can't turn the Tx off but to save the battery just take the crystal out. No crystal, no RF output, the battery lasts for ages.

Steve

[Daniel Manzato]

Ok, I'll wait for Beta 7, but meanwhile I'm gonna build the serial interface, just to test. I've read about some new TX's with a 6-pin dim socket that shorting pin 4 to pin 5 disable the HF module, not needing to take off the crystal. Does anybody know if this is true for the new Futaba Skysport 4VF? If not, how can I take the TX's crystal off the transmitter? Do I have to open the control box (unscrewing it)? In this case I'm afraid I'll lose the warranty of the product, sice I've bought it recently.
Thanks in advance again!

[Steve Lewin]

I don't know if shorting pins 4 & 5 work on that model but the crystal is the rectangular thing at the bottom left on the front of the Tx with the frequency and/or channel number on it. No unscrewing required, just pull it out.

Steve

[Daniel Manzato]

Ok, I'd like to thank all of you because I've got a lot of information here. I'll try the new cable and then post what I get here for other beginners like me.
A last doubt (just for curiosity): I've read in the Futaba manual that when you join 2 TX's with the buddie cord you must turn the student one off. Once the student side is the TX who really send all the commands through the cord, it's actually acting like the TX connected to the computer. So, why isn't there a scheme where the computer actually feed the suppliement to the TX, just like the teacher's TX feedind the student's TX through the buddie cord? I mean, in this case we could leave the TX turned off.

[Steve Lewin]

There is no easy way to get a 9.6V supply out of a computer. It doesn't have a battery like the other Tx does .

Steve

[money2k]

i have the futaba skysport 4vf transmitter and i am looking for schematics+instructions that WILL work (preferably for serial, parallel's ok) and i need them VERY soon, because i have less than 36 hours to get it up and running OR I WILL DIE
just kidding, but i would like it soon so i can have it built by then.

thnx. plz email to money2k@home.com rather than replying