4-34
888-2406-002
WARNING: Disconnect primary power prior to servicing.
Overall System Theory
Example 3
The following is an example of how the entire loop would work. For our example
the power output of the transmitter goes down due to a failed PA. This would
decrease the output of the forward power directional coupler and the voltage at the
input to the difference amp at U5-6 on the Master Controller Board. Since U5 has
almost infinite gain, the loop will try to force the forward power sample input to U5
to be the same as the APC_REF input. This will increase the APC voltage at TP3
and on the front panel APC reading. The increased APC voltage will pass through
the U5 analog switches (on the Life Support Board) bringing the input to U15-3 less
negative. This less negative voltage is sent to the IPA, increasing its output. More
drive to the PA will increase the transmitter RF output to compensate for the failed
PA.
If the RF power output were to increase, the APC loop voltage would be reduced,
lowering the IPA and PA output.
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:
Summary of Contents for Platinum Z2 CD
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Page 70: ...3 14 888 2406 002 WARNING Disconnect primary power prior to servicing Operator Guide ...
Page 130: ...4 60 888 2406 002 WARNING Disconnect primary power prior to servicing Overall System Theory ...
Page 194: ...6 38 888 2406 002 WARNING Disconnect primary power prior to servicing Troubleshooting ...
Page 196: ...7 2 888 2406 002 WARNING Disconnect primary power prior to servicing Parts List ...
