MP12
9V P
ro
[171 HIGH POWER TX MODULATOR AT27696
TR4
TIP42B
4
COMPONENT SIDE
R6
RI
27K
R3
820
TR3
BFR80
TR1
2N4289
TR2
2N4286
68
C1
I11
100n
R5
1C2
68
T4n7
TR4
--{
56 I—
R3 I-
b'
c
.—.
e
2
R4 I
RI
2
4
3
5
5
An output is available at pin 3 connected in turn to SKB6, for use with a facility module. A
parallel microphone connection is taken directly to SKB 3.
High Power Transmitter Modulator Module (17)
This module accepts the amplified and filtered microphone signal at the emitter follower TR1.
Voltage amplification takes place at TR2 and the signal is applied to the modulating transistor TR4,
via the emitter follower TR3. The modulation output is fed to the PA Module (11) to modulate
carrier and back to the Low Power Tx AF Module (9) to operate the compressor.
The emitter follower TR1 is supplied from the 10V regulated supply, TR2 and TR3 are
connected to the 14V supply.
*Transmitter Oscillator (Part of Receiver and Transmitter Oscillator Module)
The transmitter oscillator can provide one, six or twelve channels according to the module
fitted. Channel selection is made by the Channel switch (not fitted to single channel equipments)
which selects the appropriate crystal operating in the series mode at the 3rd overtone. The
frequency of operation can be adjusted by the inductive crystal trimmer appropriate to the
selected (see also Netting Procedure).
*NOTE: The Receiver and Transmitter Oscillator Module (1, 6 and 12 channel versions
are fully described under MODULES SHARED BY RECEIVER AND
TRANSMITTER).
3.12
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