Garmin AT
Rev --
© 2004 Garmin AT
GX Service Manual
7-49
Headset Distortion
Step
General Instruction
Specific Instructions
Expected Results
1 Set
all
test
equipment as
specified in Test
Equipment Setup on
page 7-17.
2
On
the
HP8920:
1. Ext. Load R 100 ohms.
2. AFGen1 to AM 85%.
3. AMPLITUDE to 1,000 µV.
3
Move test cable.
On the test box, connect the
HP8920 audio in cable to HDPH.
4 Adjust
volume
control on Comm
radio for 280 mW.
On the Comm radio, adjust the
volume control until the AC Level
reads 0.280 watts.
5
On the HP8920, from the one of
many field, select Distn.
Headset at 1000 Hz, distortion
should be < 5%.
6
NOTE: Option 019
required for the
HP8920A.
If Option 019 (the notch filter
option) is not installed, an
external variable notch filter will
be required to complete the
following tests.
7
On the HP8920, push the SHIFT
(blue key) CONFIG keys under
SCREEN CONTROL. Select
Notch Coupl. Set to AFGen1.
Push the PREV key under
SCREEN CONTROL to return to
RX TEST.
Lock notch filter to AF Gen1
Freq.
8
Notch filter freq. to
350.
On the HP8920, set the AFGen1
Freq to 350 Hz.
9
Record distortion.
Will be <12% distortion at 350
Hz.
10
Repeat steps 7 to 9 for every 200
Hz until 2500 Hz.
Audio frequency distortion will
be <12% at AM Depth of
modulation of 85% at 350 Hz to
600 Hz and < 5% from 600 Hz
to 2500 Hz.
Summary of Contents for APOLLO GX SERIES
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