Garmin APOLLO GX SERIES, Service Manual

Page: 72 / 166

Garmin AT Rev --
7-34 GX Service Manual © 2004 Garmin AT
Step General Instruction Specific Instructions Expected Results
4 Adjust audio level
input to obtain 85%
modulation ± 1%. Using the CURSOR CONTROL
knob or the
↑ arrows adjust the
AFGen1 Lvl until 85% modulation
is viewed on the HP8920 (AM
Depth). NOTE: Always approach
the desired modulation from
lowest audio input level and stop
when desired modulation is
obtained. It may be necessary to
set INCR +divide10, or INCR
SET or INCR X10 to obtain a
reading of I=0.00100 for fine
adjustment.
NOTE: Due to the 35-second
time out, the PTT switch may be
toggled from RX to TX to
maintain TX power during
adjustment.
Confirm the AF Freq. meter
reads 1 kHz at 85 % modulation
± 1%.
5 On the test box, press the PTT
switch to RX.
6 1. On the HP8920, set the AF
Anl. In to Audio In.
2. Set AC Level to W.
7 On SL display, press and hold
the NAV button (about 3
seconds) until SW VER X.X is
displayed. Rotate the LARGE
knobs until the SIDTONE LVL
reading is displayed. Record this
reading. Example: 45.
8 NOTE: Use the Service Data
Sheet to record and display
factory and customer defaults
before proceeding.
9 On the test box press the PTT
switch to TX.
10 On the Comm radio, adjust the
small knob on the right side until
the AC Level reads 0.280 watts. ≥ 0.280 watts output into 100
ohm load.
11 On the HP8920, select the AC
Level in the W field. Select the
SHIFT (BLUE KEY) REF SET.
Push CURSOR CONTROL. Set 1 kHz tone to reference
reading 0.00 dB.
12 On the Comm radio, adjust the
small knob on the right side until
the AC Level reads 10 dB down. Adjust Sidetone level until the
output level is –10 dB down into
100
Ω load.