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JR
MatchBox
Servo matching and
power distribution
Intended for modelers of giant-scale craft and others who want to use
multiple servos on a single channel, the new JR MatchBox is an
onboard electronic device that precisely matches servos used on a
single channel. Digital servos give modelers a new level of control precision,
but slight variables in control-linkage geometry still
remain—especially when more than one servo is attached to a single
control surface. Examples of this are giant-scale, TOC-style aerobatic
airplanes that use three servos per aileron and two servos per elevator
half. The slightest mismatch between these grouped servos can
cause increased current drain as the servos fight each other. Now,
however, there is an easy solution to this problem. The MatchBox
allows modelers to match servos with precision and offers servosetting
flexibility. Weighing just over 0.33 ounce, the unit is about the
same size as a small receiver and can be plugged into any channel
that drives more than one servo. Up to four servos can then be
plugged into it and, using the selector dial and buttons, the servos can
be independently adjusted. The unit allows adjustments to neutral
point (subtrim), endpoint and direction reversing.
A big plus is that the MatchBox also lets you power the servos with
a separate auxiliary battery pack! This is highly recommended if you
are driving three or four high-current servos. You do have to use a
switch harness for the second battery pack to switch off the power to
the unit. A power shunt is also included and is plugged into the battery
port if an auxiliary battery pack is not used.
The MatchBox can also be used in a Y-harness configuration
where the servos on a single channel are used for various
applications. An example is split elevator halves, with a
servo used to move each half. Each servo's endpoint
can be adjusted and, if needed, one of the servos
can be reversed to give the proper elevator
input. Typically, this kind of setup flexibility
is only offered with a programmable
computer radio.
The MatchBox is very easy to
use. The selector dial has 10
positions (0 through 9).
Positions 1 through 8 correspond
to the numbered servo
plug-in slots on the opposite
end of the unit. To select a servo
and adjust it, you simply turn the
selector to the corresponding position
number and then push either the
Increase (+) or Decrease (-) buttons to
make the desired adjustment.
• Position 0 is the default position to
which the unit should be turned for normal
operation. Any adjustments that are made are
stored in memory when the dial is returned to
0. This must be done before the airborne system
has been shut off. If power is turned off before the dial is set at 0, the
settings will be lost.
124 MODEL AIRPLANE NEWS
AT MODEL AIRPLANE NEWS, we not only tell you what's new, but we also try it out first so we
can bring you mini-reviews of the stuff we like best. We're constantly being sent the latest support equipment
manufacturers have to offer. If we think a product is good—something special that will make your modeling
experiences a little easier or just plain more fun—we'll let you know here. From retracts and hinges to glow
starters and videotapes, look for it in "Product Watch."
• Selecting any dial positions from 1 to 4 allows the modeler to make
servo neutral point and endpoint adjustments to the servos using a
combination of transmitter stick positions and the Increase or
Decrease buttons. With the control stick in the neutral position, you
can adjust the neutral point of the selected servo, and with the stick
in the extreme left or right position, the endpoints can be adjusted.
• Selecting positions 5 to 8 allows servo-reversing. As before, these
adjustments are made using the transmitter stick position (neutral)
and the buttons.
You can reset the MatchBox to the factory default settings by turning
the selector to position 9 and then simultaneously pressing the
Increase and Decrease buttons.
The MatchBox comes with detailed instructions, a short wire lead to
connect to the receiver and a battery power shunt. If you would like to
add a greater degree of servo adjustment to your next model, for
$69.99, the JR MatchBox is a handy little device to have around. I've
used it, and I like it! I think you'll like using it, too. —Gerry Vanish
JR; distributed by Horizon Hobby Inc., 4105 Fieldstone Rd., Champaign,
IL 61822; (800) 338-4639;
www.horizonhobby.com.