4-64
888-2586-001
9/15/06
WARNING: Disconnect primary power prior to servicing.
Platinum Z16HD+
Section 4 Overall System Theory
VDP which is the PA voltage plus 4 volts and VDN which is the PA voltage minus 4
volts. Basically U22 is a small switching supply providing a fl/-supply for the
op-amps U18 and U21.
4.8.7.1.10 Forward Power Sample
The forward power sample from the directional coupler enters the Life Support Board
at J2. The sample is detected by CR8 and buffered by U1-14. The DC voltage at TP8 is
directly proportional to the forward power output of the transmitter. This is sent to the
Master Controller where it is used for monitoring, display, automatic power control or
APC and calibration.
CPLR_DISC_FAULT
This is an interlock fault which will mute the transmitter if the cable to the forward
directional coupler is disconnected. The fault line is pulled up through R1 to +5V. If the
coupler is connected, the line is pulled low and no fault occurs. When disconnected, the
line will pull high and the Master Controller will mute the transmitter.
4.8.7.1.11 Reflected Power
The reflected power sample enters the board at J3. It is detected by CR10 and buffered
by U1-1. The voltage at TP7 is directly proportional to the amount of reflected power
coming back to the transmitter from the antenna or transmission line. This DC sample
voltage is sent to the Master Controller, via J1-A19, for VSWR protection and
monitoring when the Master Controller is operational. The VSWR fault comparator
output at U3-2 will only be able to effect transmitter operation in Life Support Mode.
4.8.7.2
Life Support Mode
The following contains all pertinent circuit information for operating in the Life
Support Mode. This is when the Master Controller has failed and the Life Support
Board has taken over control of the transmitter.
4.8.7.2.1 Master Controller Failure
The Master Controller has what is referred to as a “Watchdog Timer”. As long as the
micro-controller on the Master Controller board is working and executing its program
normally, the Watchdog Timer will be sending out a pulse every 1.0msec. These pulses
are detected by 1/2 of U4 on the Life Support Board (U4-4), a re-triggerable one-shot
with a 2msec time-out, which will stay triggered (SET) as long as the Watchdog Timer
pulses continue. If the Watchdog Timer pulses are interrupted (which means the Master
Controller has failed), U4 will time-out and go to the RESET mode. The Q output will
Summary of Contents for Platinum Z16HD+
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