Glenayre Electronics Inc. GL-T8311SA Manual Do Utilizador
Glenayre Document Number: 9110.00166
GL-T8xx1 Transmitter System
Revision K: 08/30/99
THEORY OF OPERATION
t526.
b94
Copyright © 1999 Glenayre
Page: 6-1
6
THEORY OF OPERATION
6.1
Metering Board
Refer to Figure 6-1 and Figure 6-2 for detailed circuit information.
6.1.1
Dc-Power Distribution
The +lug on the metering board is the main distribution point for dc power within the trans-
mitter chassis. The following connections terminate at the +lug:
mitter chassis. The following connections terminate at the +lug:
• dc power from main power supply
• dc power to rear-mounted fans
• dc power to exciter
• dc power to PA compartment (through pc traces on board)
There are several current sources for stages within the PA compartment. Each separate
circuit contains a fuse, metering resistor, and associated circuitry for measuring and
reporting circuit currents. Table 5-1, Metering Board Fuses, Indicators, and Test Points,
shows the circuits which are protected by the various fuses. Note that some transmitters do
not use every fused circuit. Table 4-7, Detail of J1 Connections (DB-25) between Metering
Board and PA RF Compartment, shows the functions of the connections between the
metering board and the PA compartment.Table 4-4, Exciter J6-to-Metering Board DB-15
J6 Pin Functions, shows detail of the connections between the metering board and the
exciter.
circuit contains a fuse, metering resistor, and associated circuitry for measuring and
reporting circuit currents. Table 5-1, Metering Board Fuses, Indicators, and Test Points,
shows the circuits which are protected by the various fuses. Note that some transmitters do
not use every fused circuit. Table 4-7, Detail of J1 Connections (DB-25) between Metering
Board and PA RF Compartment, shows the functions of the connections between the
metering board and the PA compartment.Table 4-4, Exciter J6-to-Metering Board DB-15
J6 Pin Functions, shows detail of the connections between the metering board and the
exciter.
6.1.2
Control-Signal Distribution
6.1.2.1
Transmitter Keying
The transmitter may be keyed remotely by the transmitter controller or locally by the VDT.
The exciter receives the key signal and activates internal circuitry which causes its RF
output to become active. The exciter also sends a key signal to the PA RF compartment.
The exciter signal is wired to metering-board J6-7. Metering-board circuitry relays the
signal to the PA RF compartment and the IPA second amplifier stage via J1-7. The AGC
reference signal from the exciter is passed to metering-board circuitry when the key signal
is active.
The exciter receives the key signal and activates internal circuitry which causes its RF
output to become active. The exciter also sends a key signal to the PA RF compartment.
The exciter signal is wired to metering-board J6-7. Metering-board circuitry relays the
signal to the PA RF compartment and the IPA second amplifier stage via J1-7. The AGC
reference signal from the exciter is passed to metering-board circuitry when the key signal
is active.
6.1.2.2
Power-Output Control
A reference signal from the exciter determines the nominal output power. Depending on the
exciter interface, the level may be remotely adjustable. The REF PWR dc reference signal
(J1-5 and J6-8) is also routed to the exciter for use in determining acceptable output power
and for generating alarms.
exciter interface, the level may be remotely adjustable. The REF PWR dc reference signal
(J1-5 and J6-8) is also routed to the exciter for use in determining acceptable output power
and for generating alarms.