Need some advice on Prog.Mix in PCM9Xii

[Ruud Westerhout]

Hi all,

I am using the JR Tx with my T-Rex 450 for some time now. As I am finally into getting it flying a little I am also getting into "claening" the radio. I found that two Prog.Mix (1st and 2nd) are actually switched on with me, although I really do not want to have them.
When I go into the menu of PROG.MIX1 I see that it actaully changes THRO -> THRO.
It has only three points of the cruve active 0 = -100, 3 = 0 and 6 = +100.
The same curve and also THRO -> THRO is in PROG.MIX2

I decided to delete them both. Result : The ESC find some throttle input (even though my throttle is at its lowest position) and does not allow startup. If I startup with THRO-HOLD the ESC agrees, but as soon as I take away throttle hold the engine starts to run.

Is there a way to delete them ? without the system giving me problems ? or should I keep at least one of them available.

What exactly do they do, do they kind of multiply my input with some value ?

And last but not least, does this mean that my head-speed is afflected by the settings in this prog.Mix.

Any input would be appreciated.

Regards,
Ruud

[Coolice]

Hey,

Sounds to me like you may now have to set your ESC's maximum and minimum throttle levels once again, in this case telling the ESC what is the closed position & what is full power.
Quite why you had mixes in there to start with I dont know and from your post neither do you, I am guessing the machine was setup for you perhaps?

It may also be that the transmitters ATV value on the throttle is set a little high at low stick, hence with throttle hold set the ESC arms as it see's a fully closed throttle position but then when you flick out of hold the motor starts as the ATV is below 100% travel.
This is a guess as without seeing the model it is difficult to say for sure.

I'd suggest removing the main rotor head & tail rotors, or better still (& easier) moving the motor pinion away from the main gear and trying to setup the ESC again. This way should the motor start you dont risk damage to the model or yourself.

What ESC are you using?

Let us know how you get on.
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[Ruud Westerhout]

Hi Ian,

did not see this reply until now, sorry for not reacting earlier.

I am consulted in the meantime and have now a setup where I did take away all the mixers, but to make sure the ESC likes this, I had to give the throttle a ATV of -140%. I am actually fine with this situation, unluckily have some other problems to take care of actually :(

I have a TRex 450SE with the stock 430L engine at 13t pinion (for now) and the stock 35A ESC. I did receive the 430XL lately, but had no time to install it yet. As I want to have a little more power, but not have the engine get too hot, I'd like to go down in tooth-pinion, but up in engine speed, hence the 430XL.
With my current setup I have more then 300gr. underneath the rex and if flying inside the temp of the engine gets over 60 degrees (after flying). Outside the problem is less big as our temps are dropping fast (had nightfrost already).

CU
Ruud

[Coolice]

Hey,

Ah thats ok, atleast you spotted the reply & removed the mixes.

The -140% ATV I have heard of in the past, from memory I think Futaba transmitters have required more ATV value to arm ESC's than JR for instance. I know my own have needed an extra few percent to arm properly.

The good thing with electrics is that it is so much easier to work out head speeds once you know what motor Kv your going to use and then gear accordingly.
By upping the motors power you can easily then drop a tooth or two on the pinion to allow the motor to rev a little more, inturn gaining some extra duration possibly and power.

Let us know how you get on.
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