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DX6i Sub-trim -- Thumbs Up!

JKos

rrProfessor

Redondo Beach, CA

I did a test on the use of sub-trim in CCPM mode with the DX6i. It works correctly by moving the entire servo movement range without truncating either end. One should feel comfortable using a bit of sub-trim to get servo arms perfectly aligned on this radio.

Here is some data I collected. The min, mid, max, and deltas are pulse widths in milliseconds.
Sub-trim Min Mid Max DeltaU DeltaD
0 1.305 1.505 1.705 0.2 0.2
50 1.231 1.431 1.631 0.2 0.2
100 1.157 1.357 1.557 0.2 0.2
Have fun,
John

RR rules!

12-29-2007 Over year old.
seattle_helo

Key Veteran

Seattle, WA USA

John, that's good to know. My apologies if I missed this somewhere, but did you preform the same test on the X9303? Were the results the same?

nick

12-29-2007 Over year old.
HOMEPAGE  
JKos

rrProfessor

Redondo Beach, CA

I have yet to touch an X9303. But on both the DX7 and the XP9303 sub-trim does mess things up if you have swash expo turned on. With swash expo turned off, sub-trim has zero ill effect.

- John

RR rules!

12-29-2007 Over year old.
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ExperienceRC . JR AMERICAS . HeliDirect
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Radio - Spektrum DSM

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DX6i Sub-trim -- Thumbs Up!

JKos

rrProfessor

Redondo Beach, CA

Here's a bit of DX7 data. These two graphs show the delta in the pulse width from the mid-stick pulse width as a function of stick position. One clearly shows that with swash expo off, sub-trim has no ill effect on the servo travel. Not so for swash expo on.

There is a slight bit of noise in the measurements, if you will, since hitting "10" on the In and Out indicators on the radio does not necessarily mean you are at exactly the same "10" as the previous measurement. For example, I can get the output to change several thousandths of a millisecond while still saying "10". I believe the results for swash expo off truly do overlay each other exactly if exact inputs were achievable. They are only a thousandth of a millisecond off here and there as they are.

Data for the DX6i shows the same overlay outcome as the DX7 with swash expo off.

- John

RR rules!

12-30-2007 Over year old.
giaffa

Senior Heliman

Sao Paulo - BRAZIL

Hi John,

Did you have the chance to test this with the X9303?

Thanks,
Affonso

>>> Doing it inverted is better! <<<

01-21-2008 Over year old.
HOMEPAGE  
JKos

rrProfessor

Redondo Beach, CA

X9303 has the same issue as the XP9303 and DX7. With Swash expo turned on, sub-trim has a detrimental affect.

- John

RR rules!

01-22-2008 Over year old.
giaffa

Senior Heliman

Sao Paulo - BRAZIL

Thanks!

>>> Doing it inverted is better! <<<

01-22-2008 Over year old.
HOMEPAGE  
JKos

rrProfessor

Redondo Beach, CA

Well, I have some "bad" news. The JR 12X suffers the same issue as the DX7, XP9303, and X9303. Using subtrim while Swash Exp is on creates servo throw issues. If subtrim had no negative affect, the three lines in the graph below would overlay each other perfectly just as they do when Swash Exp is off.

I can't believe they didn't fix it on this radio!!!

- John

RR rules!

09-14-2008 Over year old.
giaffa

Senior Heliman

Sao Paulo - BRAZIL

Hi John,
Did you had the chance to test this with the DX7SE?
Thanks,
Affonso

>>> Doing it inverted is better! <<<

04-15-2009 Over year old.
HOMEPAGE  
JKos

rrProfessor

Redondo Beach, CA

Affonso,
It's exactly the same.

- John

04-16-2009 Over year old.
giaffa

Senior Heliman

Sao Paulo - BRAZIL

Thanks.

>>> Doing it inverted is better! <<<

04-16-2009 Over year old.
HOMEPAGE  
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Futaba-RC . HeliProz . Boca Bearings
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Radio - Spektrum DSM

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DX6i Sub-trim -- Thumbs Up!

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