Garmin GNC 420 Maintenance Manual page 78

5.7.3.6 Receiver Quieting
1. Apply a -86 dBm RF level to the RF input.
2. Apply a Standard VOR Audio Test signal at 108.00 MHz.
3. Measure at the 500
outputs.
4. Verify the Audio SINAD or SNR is greater than 25 dB.
Audio SINAD________> 25 dB
5.7.3.7 Ident/Voice Tone Ratio
1. Apply a -67 dBm RF level to the RF input.
2. Apply a Standard VOR Audio Test signal with modulation frequency of 1020 Hz at
108.00 MHz.
3. Measure at the 500
outputs, set to 7.07 Vrms.
4. Toggle between IDENT mode and VOICE mode and verify the ident/voice ratio is greater
than 20 dB.
Ident/Voice Ratio __________ > 20 dB
5. Apply a Standard Localizer Audio Test signal with modulation frequency of 1020 Hz at
108.10 MHz.
6. Measure at the 500
outputs.
7. Toggle between IDENT mode and VOICE mode and verify the ident/voice ratio is greater
than 20 dB.
Ident/Voice Ratio________> 20 dB
5.7.3.8 Harmonic Distortion
1. Apply a -53 dBm signal amplitude modulated 30% at 1 kHz (IDENT Mode Selected).
2. Measure at the 500
outputs, and set to 7.07 Vrms.
3. Verify the total harmonic distortion is less than 5%.
THD______< 5%
400 SERIES MAINTENANCE MANUAL
P/N 190-00140-05
VOR/ILS AUDIO HI J6-16 and 500
VOR/ILS AUDIO HI J6-16 and 500
VOR/ILS AUDIO HI J6-16 and 500
VOR/ILS AUDIO HI J6-16 and 500
VOR/ILS AUDIO LO J6-17
VOR/ILS AUDIO LO J6-17
VOR/ILS AUDIO LO J6-17
VOR/ILS AUDIO LO J6-17
Page 5-27
Rev. C