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How to convert your Transmitter for independent control of the machine gun and main gun firing
...without having to move your trims each time..

there is 2 ways of doing this :
first option:
adding additional firing buttons to your transmitter ,

See here the instructions of adding additional firing buttons
to your Futaba transmitter Hints 3.htm

second option :
if you are not into this soldering in your transmitter
and as long you have an transmitter with Dual Rate or ATV/EPA
( see below explanation of these terms )
this setup is also very suitable for the newer style transmitters
with digital trims !!!

with the use of Dual Rate or ATV/EPA you can set up your transmitter
that at about 0-50% of the stick movement you are elevating the gun
and from 50-100% stick-movement you are able to fire the main- or machine-gun
without having to adjust your trims !!….

How this is done ?
We have to “cheat” during the initial setup of the DMD and MF unit's…
Here the example with the use of Dual Rate :

Determine which switch operates the Dual Rate function for the channel
which you will be using for the gun-elevation and firing…
Set the Dual Rate at “low” for max of around 50-75%
Set the Dual Rate at “high” for max of around 100-125%
Now flip the Dual rate switch back to low
Go to the setup procedure for your DMD as descript in your manual
( or take a look at the Sherman setup here on my web-page )
after that is done , test if everything works the way it should…
( you still will have to move the trims for firing )…..
flip the Dual rate switch to “high”….
Now you will find out ,
if you are moving your stick quick to the max of his travel
that either your machine-gun fires or your main-gun….
By moving the stick slower and just about ½ the way in each direction
you will operate the gun-elevation….

The setup procedure with the use of the ATV/EPA settings is similar,
Excepted that for this type of function
you don't find any switches on your transmitter ,
It's done just over adjustable potentiometers

if you have a transmitter WITHOUT dual-rate or ATV/EPA function's ,
you still can program your DMD/MF unit to fire WITHOUT the use of the trims ...
make sure you have all your stick's centered ,
go to the DMD setup-procedure ,
but move the sticks which control your gun-elevation just about 1/2 way in each direction ...
after the setup is done ,
you will be able to fire by moving the stick quickly to the end-positions ,
if you move the stick slow just 1/2 way , your gun-elevation will function

I found these setup's pretty handy and bean using it on all my tanks

                                                         June 2004 Willy -

( from Futaba's website )


Dual Rates
A switch that can make controls more or less sensitive. Lower rates are better for beginners, who tend to over-control.

ATV/EPA = Adjustable Travel Volume/End Point Adjustment
Allows separate adjustments of maximum servo travel to both sides of neutral. Helps tailor outputs for different control styles. Please refer to this FAQ for more information

Please explain dual rates, exponential, AFR and ATV and how they are related.
1. What is AFR? How is it different from ATV?
ATV is each individual servo's end point adjustment. ATV is specific to each individual servo, so adjusting the ATV to the aileron channel will not, for example, adjust the servo throw of the second aileron servo if you have flaperons set up. ATV is the 'master' control. That is to say, it takes priority over all other items. Therefore, adjusting ATV will affect anything else that is a percentage from that number, including rates, exponentials, and mixes.
AFR is essentially "primary rate" (or high rate) to go with the 'dual rate' (or low rate) function of the radio. This is what the 8U and 6X consider the first switch position in dual rate which most modelers use as their high rate. AFR is active until the dual rate is activated, and it belongs to each CONTROL or AXIS of the airplane. Therefore, adjusting AFR for ailerons in a model with flaperons will affect the throw of both servos.
Why set AFR instead of adjusting ATV? Easy. ATV is your end point for EVERYTHING the radio does....mixes, expos, everything. So if you have a low rate, mixes, etc, that you like, but you need a little more (or less) on high rate, adjusting ATV will mess up all that other work. AFR is your 'high rate' so adjust it to your liking.
2. How do I set Expos? Exponential is set independently for your 'high rate' (called AFR) and 'low rate' (called dual rate). So you have to go into AFR, set your high rate how you want it, then go to the NEXT screen to set exponential. This is your expo setting for when your dual (low) rate is not activated for that channel.
Now if you also want expo on your low rate, then go to dual rates, set up your low rate and its switch, and then set an expo here as well.

see also :

Transmitter Stick-mode