User's Manual Part 6
673)
!7
Refer to Figure 8.14.4, Figure 8.14.4 and the circuit diagram.
#$
Flat or de-emphasised audio from the receiver is selected by links to DET-AF-OUT or
RX- LINE-OUT. Receiver audio passes through a mute element to a buffer amplifier, and
then to three stages of low pass filtering. Two responses are selectable by links: 2 pole or
6 pole roll-off beyond 4kHz.
The filtered signal passes to a second mute element and level control before passing to
the line output drive amplifier. Line output impedance and attenuation are selectable by
links. Line output can be linked to line input for a shared line in, line out.
'' , 8 & &: 5
#$
The line input has terminations for two line impedances which are link selectable. The
line input level can be attenuated, if required, before passing to the line sensitivity con-
trol. Protection diodes are fitted to prevent the following amplifier stage from being
overdriven.
The amplifier provides gain and buffers the signal, which is split into two paths for
either pre-emphasis or flat response. The pre-emphasis path is via a mute element and
options linking. This signal drives TX-LINE-IN, which will override the microphone
signal. Normally, the microphone is muted on line derived PTT.
The flat response path is amplified and then passes to a mute element which drives
TX-SIG-IN. This input requires a high signal level, due to the high input impedance.
The amplifier is disabled by links, when not used, to prevent the possibility of crosstalk
and leakage to other circuitry.
Control Logic
External
Logic
T2000
Logic
Power
Suppliers
Line
Driver
Attenuator
Attenuator
Mute
Element
Mute
Element
Mute
Element
Mute
Element
Line Out
Level
Link2
BA
N=4N=2
Gain
Stage
Buffer
Amp
Line
Sensitivity
Line Out
Line In
T2000
Control PCB
Via Option
Connectors
RxAF
De-Emph.
RxAF
Flat
TxAF
Pre-Emph.
TxAF
Flat
External Circuits
Via HD D-Range
Connector