Audio Pwb Adjustment; Antenna System Changes - SAC SS-800AVS Manual

c. Modulation Limit.
Remove the AM Oscillator PWB from its connector. Install an
Extender PWB in the AM Oscillator PWB connector and install
the AM Oscillator PWB in the Extender PWB.
6.
Place Recycle PWB switch Sl in the CARR (carrier only) position.
7.
Apply AC power to the transmitter. Adjust the RF DRIVE control
~ (R39) CW until the oscilloscope indicates approximately 50
~. volts p-p across the dummy load.
8~
Place Recycle PWB switch Sl in the CONT (continuous tone)
position.
Adjust the pi-filter inductor (LI) on the AM Oscillator PWB
for a maximum RF voltage on the oscilloscope. Caution: Use
only a non-ferrous adjustment tool with LI.
i0.
Adjust the MODULATION ADJUST control (R3) CW for 95% modulation
or as desired.
6.2.2 Audio PWB Adjustment
i. Place the IDENT/CARRIER/CONT switch in the CARRIER position.
2. Apply a 1000 Hz tone to the transmitter audio input from an
audio oscillator and adjust the audio level using the audio
oscillator control and/ or R6 on the Audio PWB for 1 VRM s at
TP1 of the Audio PWB.
3. Rotate Modulation Limit Control R44 located on the Audio PWB
fully CW to defeat the~ limiter action.
4.
Adjust Voice Modulation Adjust Control R20 located on the Audio
PWB CCW until 85% modulation is measured at TB4 terminal 1.
5. Rotate Modulation Limit Control R44 CCW until the modulation
percentage is reduced to 80%.
6.2.3 Antenna System Changes
After changing the transmitter frequency, the procedure to follow
generally is to repeat the tune-up procedure in the Antenna Tune-Up
section. However, if the change involves changing the transmitted
frequency from below 415 KHz to above 415 KHz or vice-versa, simply
following the tune-up procedure will not work if the Mast Antenna
is being used. The SAC Mast Antenna is centerloaded to be resonant
at approximately 500 KHz for operation between 200 and 415 KHz and
at approximately 900 KHz for operation between 400 KHz and 625 KHz.
The resonant frequency of the antenna is chosen by selecting one
112
Southern Avionics
SS-800AVS
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