MultiPlex Cockpit Twitchy with XTR

[CustomPC]

Hi,

I have Reflex XTR with a JR plug and i have Adapters to convert from JR to Futaba and MultiPlex.

When i use my Hitec Optic 6 it all works perfectly. The Heli's are rock stable in a hover and planes are nicely trimmed.

However, when i connect my Multiplex cockpit everything works but the Heli's are twitchy and unstable. Planes are always out of trim and need some adjustment.

I'm also having some trouble with a PIC interface and the Cockpit. It intermittently drops the signal.

Can anyone shed some light as to what might be the cause of my problems with the Cockpit.

[BurkhardE]

Hi, sounds strange, my Cockpit MM works fine with Reflex for 4 years now...

But I have only that tx. Did you try calibrating the Cockpit in Reflex and storing the channel assignment (Radio menu) or even a 'simulation' (File menu) for each of both transmitters? A Hitec and a Multiplex are still not the same... ;)

And are you sure you have the right adapter (as shown at www.refelx-sim.de)?

[CustomPC]

Hi,

Yes, i re-calibrated the radio several times and it didn't improve.

My XTR interface has a JR plug and i'm using adapters for the Hitec and Multiplex radios.

I'm wondering if i should order the proper reflex interface cable for MPX radios. How could that improve things.

I want to standardize on one radio. If i can get the Cockpit working on XTR with the same smoothness as the Hitec, then i will be selling the Hitec.

[BurkhardE]

I meant not to order a new cable, but to check the pin assignments and bridges in the plug. Thought a bit soldering could help. My Cockpit works perfectly smooth (though the sticks are a bit loose, even since it was new).

[CustomPC]

I checked the adapter(s) and the MPX adapter is wired the same as the picture below.

I can't find a diagram showing how the female JR plug should be wired. Interestingly, the JR ends of my Futaba/Hitec and MPX adapters are wired differently. The red wire is soldered to the opposite tab. Is that a problem? The futaba/hitec adapter works perfectly with Reflex but not all with FMS.

[BurkhardE]

That's right, white (signal) on pin 2, brown (ground) on pins 4 and 5 (or numbers vice versa). I have short cable from this plug to a female coaxial plug where white is soldered to center and brown to an outer contact. The cable from the USB box (mine is 4 years old, a small black housing) ends in a so called Graupner plug (see picture). There the white wire is center too. There are slightly different plugs for Graupner / JR, as described at the Reflex website. There are 2 or 3 contact rings, and maybe there is a shortage between different male and female plugs. Don't know any more... :confused:

[CustomPC]

I found my problem.

The problem was the channel centre calibration. I didn't see that menu item. I was assuming that the channel assignment was also for calibrating the radio.

Multiplex and japanese brands have different pulse widths and when i plugged the Cockpit into XTR which was calibrated for the hitec the channel centres were sufficiently out of trim to disturb the flight characterisics of the models.

Once i re-calibrated channel centre for the Cockpit, most of my problems disappeared. WooHoo!

I also set all channels at 73% because i've read elsewhere in these forums that because of the bigger pulse width with MPX transmitters, that 73% is equivelent to 100% on a Jap servo and MPX's 100% is approx 120-130% on a jap servo. I did this in case the software was "tuned" for jap radios.

The twitchiness the helis was attributed to the Gyro gain. I set the max gain on the channel connected to the dial and then inadvertantly wound it back down. Once i put it back the heli's started to behave.


BTW Burkhard, is the JitterBug as good in real life as your sim models. I love it and i'm so tempted to order base on it's reflex performance.

[BurkhardE]

I'm pleased that your Cockpit is now working with Reflex. Mine needed no special adjustment at all and works really fine. (I have a special model parameter set for Reflex, my model no. 6, and Cockpit is set to the usual 1.5 ms pulse format by default, not to the special 1.6 ms Multiplex format.)

The Jitterbug seems to fly really great. I don't own the model, all I know is from the Jitterbug beta build thread (http://www.rcgroups.com/forums/showthread.php?t=185919&page=33&pp=15&highlight=jitterbug) by Martin Hunter (moderator from Kamloops, BC, Canada). Martin published several videos there, you should take a look at them. It seems the Reflex JB flies pretty relaistic, but see yourself! (I would dare to buy one, there were several owners writing very positive.)