BEI Electronics LLC 7EPTX-AM5E Manuale Utente

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1-40.

The binary power level 2 command from latch U17 is routed to:  1) BCD-to-decimal

decoder U18 and 2) multiplexer U39.  U18 is designed to decode the binary number from

U17 and output a HIGH on the appropriate control line to indicate the selected power

level.  With the power level 2 selected, a HIGH from BCD-to-decimal decoder U18 is

applied to AND gate U20A. With antenna 1 switch S1 programmed to operate with power

level 2, a  HIGH from OR gate U12A is also applied to U20A.  U20A will respond by

routing a HIGH to OR gate U21C.  U21C will output a HIGH to OR gate U13B.  U13B 

will output a HIGH to U22B.

1-41.

AND gates U69B, U71B, and U71D monitor the status of the external interlock, the

remote control failsafe input, and the external/exciter mute commands.  The circuit

functions to determine if all the interlocks are closed, the remote control unit is

operational, and the exciter is operational.   If the external interlock is closed and the

remote control unit is operational, U71D will output a HIGH to U22B.  If no external or

exciter mute commands are present, U13C will output a LOW to inverter U25A.  U25A 

will output a HIGH to U22B.  With a HIGH antenna interlock signal from U13B

indicating a proper antenna/power level selection, U22B will output a HIGH operate

command to the power control circuit, an exciter/power supply mute circuit, and a high

reflected power circuit.

1-42.

The HIGH operate signal is routed to the power control circuit to allow the transmitter to

be energized.  If the remote control unit fails, or the external or exciter mute signal is

activated, U22B will output a LOW operate command.   The LOW operate command

mutes: 1) the exciter PWM signal and 2) the power supply circuit board(s).  If the cabinet

or external interlock is opened,  AND gate U71B will output a LOW cabinet command.  A

LOW cabinet command configures the power control circuit to operate the transmitter to

off.  U71D will output a LOW to:  1) extinguish the interlock indicator and 2) generate a

LOW operate command.  A LOW operate command mutes:  1) the exciter PWM signal and

2) the power supply circuit board(s).

1-43.

POWER CONTROL CIRCUIT. 

 Binary power level information from latch U17 is applied

to multiplexer U39.  U39 decodes the power level number and selects a reference voltage

from a potentiometer network.  Potentiometers R2 through R6 provide a voltage reference

proportional to output power for power levels 1 through 5.    For example, power level 2

selected for operation.  With power level 2 selected, U39 will select a reference voltage 

from potentiometer R5.  The voltage is routed through buffer U40B to digital-to-analog

converter U42.

1-44.

U42 is designed to output a reference voltage to a power control driver circuit.  U42 is

controlled by up/down counters U30 and U31, multiplexer U27, priority encoder U28, and

divider U26.  The up/down counters, multiplexer, and priority encoder function to output

clock signals to U42 in response to fault conditions.  U42 will respond by

increasing/decreasing the power reference voltage in response to foldback and release

commands from U27.  With no foldback or release signals,  U42 will output the power 

level 2 reference voltage without change to a power control driver circuit.