Southern Avionics Company SD100 Manual Do Utilizador

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1.0

PRELIMINARY SET-UP

1.1

Successful alignment of this PCB requires a fully functional system and a previously 
aligned  RF section. 

1.2

Verify that all ac and dc power switches are turned off 

1.3

Adjust R5 fully CW

1.4

Connect a PC to the Controller / Monitor local port with an RS232 null modem cable. 

1.5

Turn the PC on and Load and Run the USER  Software supplied with the System

1.6

Turn on AC main power switch

1.7

Turn on the Controller / Monitor AC Distribution power switch

1.8

Turn on the Transmitter 1 AC Distribution power switch

1.9

On the PC click on Open Port

1.10 Click on ID CONFIG and set up for the normal frequency of operation.

1.11 Click POWER ON

1.12 Set the RF POWER level to Zero

1.13 Set Mode to CARRIER

2.0

PULSE WIDTH MODULATOR ALIGNMENT

2.1

 Scope  TP2 and adjust R9 for a 75,000  ±500 Hz,  +4 VDC to -4 VDC triangle-wave.

2.2

Scope TP3 and observe a 75000 Hz square wave that is +12Vpk and less than 50% duty 
cycle. 

2.3

Adjust R28 for an exact 45% duty cycle square-wave at TP3. Note that this setting is critical 
and is the basis for modulation purity and all subsequent power alignment. Calibration of 
the RF section is based on this waveform.

2.4

Set the RF POWER to the maximum allowed power or 100 watts whichever is LEAST

2.5

Measure the output power with a calibrated scope at the dummy load. 

2.6

If the power output is not within 2% of the power setting then the output of the controller/
monitor must be verified and the calibration pot on the PA Power supply PCB must be re-
adjusted. This is easy to do. It must be stressed that tweaking of the duty cycle to achieve 
alignment is not acceptable.

2.7

Set up the scope attached to the dummy load for monitoring the modulation envelope.

2.8

Set the RF POWER to 25 watts.

2.9

Set the Mode to CONTINUOUS

2.10 Set the Modulation to 100%

2.11 Adjust  R30 until the modulation envelope is indicating 100% modulation

2.12 Set the RF POWER level to the maximum power allowed.