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QCM Tips and Tricks
Apr/3/2011
Tips and Tricks
What NOT to do
with the QCM:
Do not use QCM to measure your aircrafts fully amperage
load. There are other devices on the market that will work for
that. The QCM is designed for a single servo on each
channel. Not a battery on channel and plane on the other end.
Since the QCM is a new product I am sure there will be
more for this section later.
Tips and Tricks:
ISOLATE YOUR WORK:
When hooking up your QCM, if at all possible try to isolate
the surface you are testing for binding, or are trying to match
up. In other words if you are going to test your Right Aileron, you
will want to disconnect all other surfaces from you RX before you plug in your
Right Aileron. All testing should be done this
way.
REASON: Since the sticks on our transmitters do
more than one thing, (Throttle/Rudder)-(Elevator/Aileron) it is very
easy to bump one surface while trying to test another just in moving the stick
around. When this happens you are causing a voltage jolt
(spike/fluctuation) on your RX buss, which in turn will cause a spike to go
through the QCM. This will not hurt the QCM, however it can make it
hard to read. If you are fine with that explanation
skip the next paragraph,,, (I
would!)
CAUTION: Calculation Ahead>
If your Servo
is drawing 1.1 amps (I ) at a voltage of 8.4 (V ), the
wattage will be 9.24 (P ) or ( I x V = P ).... Now
lets say you have your whole plane 40% wired up and you are trying to test
your Right Aileron, you have a Gang of 4 8711's on your Rudder that you keep
bumping. When you bump that rudder stick you notice that your right
Aileron numbers go crazy. What is happing when you do this is?
You are messen with (V ) which will change the equation, and will show
up in elevated Amperage readings. So in the first equation we
figured out that the 8711 was using 9.24 watts (P ) to maintain
its position. When you bump your rudder system you are dropping the
Voltage of the buss to 7.6volts (V ). Now we must work the
equation backwards ( P / V = I ) or 9.24(P ) / 7.6(V
) = 1.2(I ) . As you can see we
have gained .1 or 100mA's just from a spike on the buss. This is why
we recommend that you Isolate what you are testing.
ONE AT A TIME:
When hooking up your QCM try to land your Servo leads one
at a time. Meaning Start on Servo#1, observe the reading, now plug
in Servo#2 etc. This will allow you to make adjustments as you go
along. You can plug everything in all at once (Let-her Rip Mode),
however doing it this way can make it hard to figure out exactly which Servo
that is causing the binding. Remember in a Gang of 4, 1 Servo can
cause all the Servos to buzz and draw excessive current. Eventually
you will get thing sorted out doing it this way, however it is not optimal and
we suggest you do it one at a time.
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