Garmin APOLLO GX SERIES, Service Manual

Page: 84 / 166

Garmin AT Rev --
7-46 GX Service Manual © 2004 Garmin AT
Intercom/Monitor
Step General Instruction Specific Instructions Expected Results
1 Set all test
equipment as
specified in Test
Equipment Setup on
page 7-17.
On the HP8920:
1. Set AMPLITUDE to 1000
µV.
2. Set Ext. Load R 4 ohms.
3. Set AFGen1 Freq. to 500
Hz. Set AFGen2 Freq. to
2000 Hz.
4. Set AFGen2 To field to
Audio out at 50 mV.
2 Adjust volume
control on Comm
radio for 12 W.
On the Comm radio, adjust the
volume control until the AC Level
reads 12 watts. ≥ 12 watts output into 4 ohm
load (mounted in test fixture) at
a volume level from 0 to 12
watts.
3 Mute speaker test. On the test box, set INT/OFF
switch to INT. The speaker audio out will be
0 W.
When the Intercom switch is on,
the speaker is disabled.
4 Check headset. On the test box:
1. Move the SPKR OUT cable
to the HDPH test jack.
2. Set the TEST HDPH/LOAD
switch to TEST HDPH.
When the Intercom switch is on,
the Comm radio signal is routed
to the headphones.
5 Check headset
volume.
On the HP8920 set:
1. EXT LOAD TO R to 100
ohms.
2. Adjust the volume control on
the HP8920 to monitor the
0.500 kHz tone.
The HP8920 AF Freq. meter
will read 0.500 kHz ± 15 Hz.
6 On the Comm radio, adjust
volume control to read 0.280
watts on the HP8920 AC Level
meter.
7 Set to reference. On the HP8920, select the AC
Level Field (W), then press
SHIFT REF SET and push
CURSOR CONTROL knob. The Comm channel is set as
reference audio level.
8 Check if microphone
mutes radio.
On the test box move the
TEST/MIC1 switch to MIC1. The HP8920:
1. AF Freq. meter will read
1500 Hz ± 15 Hz.
2. The AC Level Meter will
read 1 dB greater than
reference.