.  Hill Country Research Innovations in Telecommunication and Automation   Aircraft Radio Tester .

This tester has been developed to help A&P mechanics, avionics technicians and pilots troubleshoot communication problems.  It helps determine if the airplane has a transmitter, antenna, microphone or cable problem.

The device receives radio frequency signals, processes them and displays them on two LED bars.  The left row of green LEDs shows the carrier field strength and the right row of yellow LEDs shows the modulation level.  A sound varying with field strength and modulation level is played at the same time.

After turning the system on it goes through a audible and visual test cycle.  Then unit is ready for operation.  The red LED blends in about every ten seconds and reminds the operator that the unit is switched on.

On airplanes with multiple antennas the unit can also be used to test which antenna is transmitting.  For close range the device can be wrapped partially in aluminum foil to attenuate the signal.

When unit is switched on and the transmitter is off, no green or red LEDs should be on.  If some stay on there might be another radiation source in the vicinity (cell phone, wireless camara, etc.) which could compromise the measurements.  In this case move to another location or find and turn off radiation source.

The unit runs on a normal 9 V battery.  If the initial test cycle appears in the middle of a measurement or if LEDs stay lit after turning  the transmitter off,  the battery is weak and should be replaced.

The range is about 100 feet.  An optional external antenna extends the range.

The unit can also be supplied with a built-in 125 MHz transmitter.  This allows for testing the receiver of the aircraft radio too.
 

The price for the standard unit is $ 185.00, with built-in transmitter $225.00.