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UNIT DESCRIPTION
The Creative Electronics model ELT 1091A ELT tester was designed for use by aviation
maintenance technicians and others who have the need to routinely test ELTs and PLBs to
determine that they will work properly when called on to do so. As such it was not designed to
be used as a laboratory test instrument to obtain the original certification of such devices. The
tester will however determine if the ELT/PLB is working properly, and decode and display the
message it is sending. The tester has been designed to be simple and intuitive to use and
provide a thorough test of the ELT/PLB and supply a simple go / no go indication along with the
message information generated by the ELT/PLB. It is up to the user of the tester to make sure
that the sent HEX code and country of registration are correct. (SEE PAGES 12 & 14)
The tester consists of two receivers, one for 121.5 Mhz. and the other for 406.0 to 406.1 Mhz.,
a dedicated MCU, a clock timing reference source, an 80 character display, 4 bicolor LED’s, an
audio amplifier with speaker and a substitute 50 ohm antenna load.
The ELT 1091A tester incorporates a power switch which is used to determine which of the two
operating modes is desired, POWER METER or FIELD STRENGTH. The other switch, a spring
loaded center off toggle switch is primarily used to cycle thru the various display pages as well
as control several other functions to be described later. The results of the various tests are
provided by 3 red/green LEDs and the 80 character LCD display arranged with 4 lines of 20
characters each.
Power is supplied by 8 AA batteries. A special monitoring circuit turns the tester off if there is
no activity for 15 minutes to conserve the batteries. If the battery voltage gets below a level
that will affect the accuracy of the tester, the BATTERY LED will turn red, and the display will
display a message to replace the batteries, and the tester will become disabled. An additional
circuit monitors the internal temperature of the tester and will disable the tester if the
temperature is out of the normal operating range that would affect the accuracy of the tester.
The display will display either a temperature too high or too low message. The tester will
remain disabled until the internal temperature is returned to the normal operating range.
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