Garmin GTR 225 User Manual

190-01182-02 GTR 225/GNC 255 TSO Installation Manual
Rev. F Page 6-13
6.4.3.4 COM Update Page
The COM UPDATE page loads the COM software to the GTR/GNC. See section 6.8 for instructions on
loading COM software to the GTR/GNC.
Figure 6-18 COM Software Update Page
6.4.4 Audio Configuration Group
6.4.4.1 COM Sidetone Page
COM sidetone is the audio spoken into the COM microphone. The COM SIDETONE page adjusts the
volume, mode and pilot control of the COM sidetone. This setting only affects the volume of the sidetone
for the GTR/GNC COM during PTT. To adjust the COM sidetone volume, turn the inner knob to the
desired value. This field is adjustable in the range of 0 to 100. The default is 50. See table 6-13 and
table 6-14 for descriptions of each selection.
NOTE
The COM sidetone volume set in configuration mode is the value used when the FIXED
COM sidetone mode is selected in normal mode.
Figure 6-19 COM Sidetone Page
Table 6-13 COM Sidetone Mode Selections
(Software Version 2.10 or Later)
NOTE
When INTERNAL is selected, the audio signal has higher dynamic range and has a more
full sound. However, transmitted audio quality issues may not be noticed by the pilot until
notified by air traffic control (ATC). Some pilots prefer the sound quality of the internal
sidetone versus the external sidetone.
Selection Description
EXTERNAL (DEFAULT)
The COM sidetone audio that the pilot hears is the demodulated audio
signal that is actually going to the antenna to be transmitted.
INTERNAL
The COM sidetone audio that the pilot hears is the audio signal from the
headset microphone before it is filtered for transmission.

Garmin GTR 225 Specifications

General

Input Voltage	11-33 VDC
Operating Voltage	11-33 VDC
Operating Temperature	-20°C to +55°C
Frequency Range	118.000 MHz to 136.975 MHz
Channel Spacing	25 kHz
Transmit Power	10 W
Current Consumption	1.5 A (max transmit)