MGL Avionics GF-1 Operating Manual

Introduction

The GF-1 is a 2 1/4” G-force meter capable of measuring G-forces exerted in an aircraft up to +-10g. The forces acting on
the aircraft are easily seen on a large backlit graphic display both numerically and graphically. The GF-1 also has the
facility to record maximum G-forces obtained in permanent memory as well as a temporary memory to record G-forces
reached from the time of power up. It also features 2 independent cycle counters to capture the amount of times a preset
force has been exceeded. The GF-1 is able to measure G-forces even if the instrument is not mounted exactly on the
vertical axis of the aircraft.

1 Features

• Typical, accurate range up to 20g (from -10g to +10g)

• Records maximum measured forces in permanent memory (both positive and negative G-forces), with
password protected reset facility

• Two independent cycle counters record the number of times a preset force has been exceeded

• Temporary memory for maximum positive and negative G-forces encountered (typically during a flight)

• Clear, large readable G-force numerical value (10G positive and negative)

• Scalable graphic analog display of force acting on the aircraft

• 2 axis design of the instrument allows mounting in sloped panels (i.e. panel not exactly vertical)

• Quick calibrations function for operation at temperature extremes using Earth’s gravity

• Bilingual support (English or French)

• Standard 2 1/4” aircraft enclosure (can be front or rear mounted)

• Rotary control plus 2 independent buttons for easy menu navigation and user input

• An external alarm output as well as a red LED illuminates every time the aircraft exceeds a preset G-force

• Large backlit graphic LCD with adjustable contrast

• Wide input supply voltage range of 8 to 30V DC with built in voltage reversal and over voltage protection
for harsh electrical environments

• Light weight design

• 1 year limited warranty

GF-1

+-10g Tilt Compensated dual range
aviation G-force meter

Operating Manual – English 1.05

GF-1 Operating Manual Page 2

2 GF-1 Layout

3 Main Display

Backlit Graphic LCD Display:

Contrast and backlight can be adjusted
in the menu system

Harness:

Harness connects
to power

Up/F1 Button:

Up button in menu system
Reset cycle counter values
in normal mode

Down/F2 Button:

Down button in menu
system
Reset temporary
(current flight) G-force
maximum values in
normal mode

Rotary Control (Up/Down) & Enter Button:

Press the rotary control during normal mode to access the menu
system. Rotate anti/clockwise for up/down menu scrolling. During
normal mode rotating the switch will display the permanent memory G­force maximum values.

LED Alarm:

The red LED will illuminate if any of
the G-force cycle counters have
been exceeded

Maximum value
reached during current
flight indicator

Maximum positive force
recorded during a flight

Maximum negative
force recorded during a
flight

Digital G-force
display

Number of times the
positive limit has
been exceeded

Number of times the
negative limit has
been exceeded

Analog G-force
meter bar graph

Programmable G­force scale

GF-1 Operating Manual Page 3

3.1 Reset cycle counters display

This display can be accessed by pressing the F1 key during the normal display mode. Pressing the F1 key again will
reset the cycle counters. Pressing any other key will cause the GF-1 to return to the normal display mode.

3.2 Reset current flight/temporary maximum G-force values display

This display can be accessed by pressing the F2 key during the normal display mode. Pressing the
F1 key will reset the temporary/current flight maximum values to the current G-force value. Pressing
any other key will cause the GF-1 to return to the normal display mode.

3.3 Permanent maximum G-force values display

This display can be accessed by turning the rotary control either clockwise or anti-clockwise. Pressing the F1 key will
reset the permanent maximum values to the current G-force value. Pressing any other key will cause the GF-1 to return to
the normal display mode. If the max G-force reset code is not equal to 0000, then the code entry screen will be displayed.
To avoid false recordings, the maximum G-force function is only activated 10 seconds after the instrument has powered
up.

4 Menu System

Pressing the rotary control button during the normal display mode will cause the GF-1 to enter the menu system. Use the
up/down keys or the rotary control to navigate through the menu system.

Note: The permanent maximum values are
stored in non-volatile memory and are recalled
on power-up.

Note: The cycle counter values are stored in non-volatile
memory and are recalled on power-up.

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4.1 Exit Menu

Pressing the rotary control on this menu item will cause the GF-1 to exit the menu system. All
changes made during navigation of the menu system will be saved in non-volatile memory on exiting
the menu system. If you remove power before exiting the menu the instrument will not save any
changes.

4.2 Display Setup

Move the highlight over the “DONE” menu item and press the rotary control to return to the main
menu.

Select this menu option to adjust the display contrast.

Select this menu option to turn the backlight on or off.

Select your preferred language for the GF-1. English or French.

4.3 G-Force Setup

The G-force menu allows the user to adjust all the G-force related parameters

Note: (ADC Values and Calibrate Menus are only visible when powering up the unit and pressing the
Rotary Control). The text “CALIBRATE” will appear on the intro screen when entering this mode.

Warning: The Calibrate Menu is for technical personnel only. Changing any values in this menu may
cause the instrument to display incorrect information, and may require the instrument to be returned to
the factory for recalibration.

GF-1 Operating Manual Page 5

Move the highlight over the “DONE” menu item and press the rotary button to
return to the main menu

Set the maximum G-force value that you would like the analog bar graph to display

Set the positive G-force limit above which the cycle counter should increment
This would typically be set to the maximum allowable G-force rating of your aircraft (positive G­force)
The cycle count is retained if power is removed

Set the negative G-force limit above which the cycle counter should increment
This would typically be set to the maximum allowable G-force rating of your aircraft (negative G­force)
The cycle count is retained if power is removed

This function allows a quick calibration of the Z-axis G-force sensor. You would typically use this
function to set the G-force reading to exactly 1.0g (Earth’s gravity) in cases where the instrument is
operated at temperature extremes (very hot or very cold). Temperature has a slight effect on the
sensor and this function helps you to maintain best possible measurement accuracy should you
operate at temperature extremes. In order to use this function, the instrument faceplate should be
vertical to the Earth’s surface within 10 degrees.

Use up/down keys or the rotary control to increase or decrease the reading. Approximately four key
presses are required for 0.1g. Ensure that the instrument is in fact exposed to a force of 1g (Earth’s
gravity) in the vertical direction. Do not use this function in flight. Do not use this function if the
instrument is more than 10 degrees from the vertical.

This menu option allows you to change the permanent maximum G-force values reset code. You will
first be prompted to enter the current code followed by entering in a new code followed by re­entering the new code. If the new code and the re-entered code is the same, then the maximum G­force reset code is changed. Default code is 0000.

4.4 ADC Values

Note: This menu item is for technical personnel only, and is not displayed during the normal

operation of the instrument. Please see section 4 above on how to access this menu item.

This menu displays the ADC values that have been read from the 2-axis G-force sensor

GF-1 Operating Manual Page 6

4.5 Calibrate

Note: This menu item is for technical personnel only, and is not displayed during the normal

operation of the instrument. Please see section 4 above on how to access this menu item.

Move the highlight over the “DONE” menu item and press the rotary button to return to the main
menu

Calibration procedure :

The above 2 menu functions allow the unit to be calibrated using the Earth’s gravity as a reference. Follow the steps
below when performing a calibration. The order of these steps is important:

Step one:

Place the instrument such that the faceplate is exactly vertical (normal operating orientation, normal side up as it would be
installed in an aircraft). Select the Calibrate 1g menu option. You will see a message confirming the action.

Step two:

Place the instrument such that the faceplate is exactly horizontal with the display on top. If placed on a table, you would
be looking down onto the display from above. Select the Calibrate 0g menu option. You will see a message confirming the
action.

Step three:

Place the instrument in the vertical position again (same as in step one). Select the Calibrate 1g menu option again.

You have now calibrated both the horizontal and vertical G-force using Earth’s gravity as the reference.

5 Loading Factory default settings

Pressing and holding the F1 and F2 keys simultaneously on power up will cause the GF-1 to load pre-programmed
factory default settings. The following screen will be displayed:

GF-1 Operating Manual Page 7

6 Operating the alarms

The red LED will illuminate and the alarm contact will close when the G-force exceeds any of the G-force cycle counter
thresholds. The alarm contact will remain closed until any button is pressed to acknowledge the alarm or until the G-force
has returned below the G-force cycle counter thresholds. The alarm output can be used to switch an external alarm
indicator. The external alarm contact is an open collector transistor switch to ground with a maximum rating of 0.5A DC. It
is possible to wire the alarm contacts of several Stratomaster instruments in parallel should this be desired.

7 Cleaning

The unit should not be cleaned with any abrasive substances. The screen is very sensitive to certain cleaning materials
and should only be cleaned using a clean damp cloth.

8 GF-1 Specifications

Operating Temperature Range -10ºC to 50ºC (14ºF to 122ºF)
Storage Temperature Range -20ºC to 80ºC (-4ºF to 176ºF)
Humidity <85% non-condensing

Power Supply

8 to 30Vdc SMPS (switch mode power supply) with built in 33V over voltage
and reverse voltage protection

Current Consumption Approx. 39mA @ 13.8V (backlight on) 10mA @13.8V (backlight off)

Display

114x64 graphic LCD display. Contrast and backlight is user configurable,
green/yellow backlight

ADC 12bit over sampled successive approximation
Dimensions See Infinity series dimensional drawing
Enclosure 2 1/4” ABS, black in color, front or rear mounting
Weight Approx. 104 grams
Alarm contact current rating Open collector transistor switch to ground. Maximum rating 0.5A DC
Non-volatile memory storage 100000 write cycles
G-force range +-10g typical
Maximum error over full range Less than 1% of full scale when operated at calibration temperature
Temperature drift 0.002g / degree C or less

Warning: The GF-1 is not waterproof. Serious damage could occur if the unit is exposed to water

and/or spray jets.

GF-1 Operating Manual Page 8

9 Installation

The instrument must be installed exactly horizontal (when viewed from the front) so the force sensor is correctly aligned
with the yaw axis of the aircraft (Z axis). The faceplate alignment should be such that it is at less than +-20 degree tilt
relative to the Z axis. The instrument is tolerant of sloped aircraft panels but in order to use the quick calibration function
the slope relative to the Z axis should not exceed +-10 degrees. More acute slopes can be tolerated, but performance
should be checked on an individual basis.

9.1 Connection Diagram

The use of an external 1A fuse is recommended. Connect the supply terminals to your aircrafts power supply. The GF-1
can be used on both 12V and 24V without the use of any pre-regulators. Ensure that the supply voltage will not drop
below 8V during operation as this may result in incorrect G-force readings.

9.2 GF-1 DB9 Cable connections

DB 9 Pin Color Function

1 Black Ground
4 NC Airtalk communication (Not connected)

Used for firmware upgrading
6 Red 8-30Vdc power
9 White Alarm Output

GF-1 Operating Manual Page 9

10 Warranty

This product carries a warranty for a period of one year from date of purchase against faulty workmanship or defective
materials, provided there is no evidence that the unit has been mishandled or misused. Warranty is limited to the
replacement of faulty components and includes the cost of labour. Shipping costs are for the account of the purchaser.

11 Disclaimer

Operation of this instrument is the sole responsibility of the purchaser of the unit. The user must make themselves familiar
with the operation of this instrument and the effect of any possible failure or malfunction.

This instrument is not certified by the FAA. Fitting of this instrument to certified aircraft is subject to the rules and
conditions pertaining to such in your country. Please check with your local aviation authorities if in doubt. This instrument
is intended for ultralight, microlight, homebuilt and experimental aircraft. Operation of this instrument is the sole
responsibility of the pilot in command (PIC) of the aircraft. This person must be proficient and carry a valid and relevant
pilot’s license. This person has to make themselves familiar with the operation of this instrument and the effect of any
possible failure or malfunction. Under no circumstances does the manufacturer condone usage of this instrument for IFR
flights.

Other instruments in the Stratomaster Infinity series

ALT-1 Precision encoding altimeter and vertical speed indicator
ALT-2 Precision encoding altimeter and vertical speed indicator with a serial RS232

transponder output

ASI-1 Airspeed indicator (ASI) with automatic flight log
ASX-1 Encoding aviation altimeter with serial output and airspeed indicator (ASI)
AV-1 Artificial horizon and magnetic compass indicator
BAT-1 Battery voltage and current monitor
E-3 Universal engine monitor
FF-1 Fuel Computer (single or dual fuel tanks)
GF-1 +-10G tilt compensated dual range G-force meter
MAP-1 Manifold pressure and RPM Indicator
RV-1 Universal engine RPM and rotor RPM Indicator
RV-2 Universal turbine RPM / RPM factor display
RTC-2 Aviation real time clock (RTC) and outside air temperature (OAT) display
TC-1 4-Channel thermocouple indicator
TP-1 Universal temperature and pressure gauge

Note: Product warranty excludes damages caused by unprotected, unsuitable or incorrectly wired

electrical supplies and/or sensors, and damage caused by inductive loads.

The manufacturer reserves the right to alter any specification without prior notice.