SOUTHERN AVIONICS COMPANY
Model SA100 Dual4-30 Installation and Operation
4.8.1 Code Tone Modulation Adjustment
1. Check that MONITOR is in DSBL.
2. Set RF METER switch to SET and adjust METER SET control to the SET line.
3. Set RF METER switch to READ and set MODE switch to CONT. Adjust MOD for the desired
modulation percentage.
4.8.2 Voice Modulation Adjustment
1. Switch RF OFF.
2. Place the Meter Switch in the AUDIO position.
3. Apply the normal audio line signal to the 600 ohm balanced audio line input terminals on the
transmitter rear panel. This may be applied from an oscillator or from a recorder, telephone
pair, or other device.
4. Rotate the Audio Input Level control (R6) on the Audio PWB CCW to increase the meter
deflection until the average meter deflection is between half and full scale. Disconnect the
audio line signal before going to the next section.
4.8.3 VSWR
Check that MONITOR is in DSBL. Place the MODE switch in CONT and note the REFL
reading. VSWR shutdown will be set to shutdown the system at some value of reflected
power greater than this "normal" operation value. The value of reflected power that will
occur in "normal" operation depends on the antenna, the frequency, and how much the
antenna environment changes under "normal" conditions. A reasonable setting for most
conditions is two times the "normal" value read above. As a guide to determine this set-
ting, the following table shows VSWR as a function of percent reflected power.
Reflected Power VSWR
1 percent 1.22
5 percent 1.58
10 percent 1.92
20 percent 2.62
1. Set the MODE switch to CONT, turn RF LEVEL fully CCW and turn RF OFF.
2. Disconnect the RF cable to the Antenna Coupler.
3. Re-apply power with RF switch.
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