Garmin APOLLO GX SERIES, Service Manual

Page: 70 / 166

Garmin AT Rev --
7-32 GX Service Manual © 2004 Garmin AT
1. Transmitter Tests Using the HP8920 Test Set
This test will require MON and Test Mode adjustments. Record MON and Test mode settings
before proceeding. See the Service Data Sheet located in chapter 21 of this manual.
Flip/Flop Input (Not present on GX50/55)
Description:
The frequency flip/flop input is a discrete input intended for connection to a
momentary button to aircraft ground.
Setup:
Connect the unit to nominal input supply. Connect a momentary switch from the
flip/flop input to ground.
Operation:
After powering the unit on, press the COM smart key to see the frequencies.
Ensure that the active and standby frequencies are not the same. Push the
flip/flop momentary switch several times.
Verification:
Verify the frequencies flip/flop when pressing the momentary switch.
TX Power
Step General Instruction Specific Instructions Expected Results
1 Set all test
equipment as
specified in Test
Equipment Setup on
page 7-17.
No Modulation.
2 Key transmitter. On the test box press, the PTT
switch to TX.
3 Record power. Record TX Power from HP8920. TX PWR >8 watts with no
transmitter audio at 25°C + 4°.
TX PWR >7 w at –20°C and at
+55 °C.
Optional:
repeat this
test with DC input voltage
between 10 VDC and 40 VDC.
The battery protection circuit is
on below 13.75 V.
At 10 VDC input the transmitter
power should be 6 watts. At 9
VDC the PTT should lock out.
4 On the test box, press the PTT
switch to RX.
5 Repeat this test at frequencies
118.0 MHz and 136.975 MHz.