Garmin AT
Rev --
7-52
GX Service Manual
© 2004 Garmin AT
Receiver Dynamic Range
Step
General Instruction
Specific Instructions
Expected Results
1 Set
all
test
equipment as
specified in Test
Equipment Setup on
page 7-17.
2
RF Out to Dupl. Sig.
Gen. Mod Lvl. To
30%.
Amplitude to 1000
µV.
On the HP8920:
1. Set RF OUT/Dupl.
2. Set AFGen1 to AM 30%.
3. Set AMPLITUDE to 1000
µV.
4. Set Ext. Load R 4 ohms.
3
Move RF cable.
On the HP8920, move the
RFIN/OUT cable to DUPLEX out
connector.
4 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.
5
Open squelch.
On the Comm radio, pull the
Squelch knob out (disable
squelch).
6
Find 6 dB SINAD
reading.
On the HP8920, set the value
field in the SINAD meter reading
to average (AVG) at 10.
Set AMPLITUDE using the
↑
↓
arrows until the SINAD meter
reads 6 dB SINAD.
Reference signal level
≤
2 µV
(hard) for 6 dB S+N/N with 30%
modulation at 1000 Hz.
7
Add 107dB.
On the HP8920:
1. Select the AMPLITUDE field.
Press the GHz/dBm key.
2. To calculate upper dynamic
range, add 107dB to
reference signal level.
Converts µV to dBm.
Example: –107 dBm +107 = 0
dBm.
8
Set HP8920 to 224
mV.
On the HP8920:
1. Set the AMPLITUDE field to
upper dynamic range.
2. Select the SINAD field and
change to Distn.
Dynamic range is 107 dB with
<5% distortion.
9
Record as pass or fail.
Summary of Contents for APOLLO GX SERIES
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