4-34 888-2408-002
WARNING: Disconnect primary power prior to servicing.
Overall System Theory
4.7.1.2.1 Manual Power Control
It is possible to shut off the APC by opening dip-switch S1-10 (Open = OFF) on the
Master Controller Board. This switch opens the APC Loop, disconnecting the APC
voltage from the IPAs. When S1-10 is opened, MANUAL PWR REF R25 on the
Life Support board controls the transmitter power output. R25 also serves as the
power control for Life Support Mode which means the Master Controller Board has
failed. If the Master Controller fails, U5 pins 1-2 are opened, removing the APC
voltage from the IPAs, breaking the APC loop. In Life Support Mode, R25 is set to
operate the transmitter at 25% of rated power. Proper setting of R25 requires an
external wattmeter and is covered in Section V, Maintenance under “Setting Life
Support Power Level.”
!
CAUTION:
IN LIFE SUPPORT MODE THERE IS LIMITED OVERLOAD PROTECTION
AND NO FOLDBACK FUNCTIONS. ADJUSTING R25 TO MORE THAN 25%
RATED POWER WILL CAUSE THE TRANSMITTER TO SHUT OFF AND
COULD DAMAGE THE TRANSMITTER. REFER TO SETTING LIFE
SUPPORT POWER LEVEL IN SECTION V, MAINTENANCE.
4.7.2 Calibration Factors and A/D Values
The configuration menus in the Diagnostics Display contain the calibration factors
and A/D values used by the transmitter for calibration, operation and protection.
The cal factors are calculated by the micro when the transmitter is calibrated. The
A/D readings are the decimal equivalents of the forward and reflected power sample
voltages. The following is a listing of their nominal values:
Calibration Factors:
• Forward Factor - 0.007697
• Reflect Factor - 0.000306
• APC_Factor - 7.58
• EXC_Factor - See Factory Test Data (Frequency dependent)
• IPA_Factor - See Factory Test Data (Frequency dependent)
A/D Readings
• DAC_APC_REF - 660 (nominal)
• A/D_FWD_PWR - 806 (nominal @ 5kW)
• A/D_RFL_PWR - 700 (nominal @ 150W reflected)
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