Codan NGT 2010 RF Technical & Service Manual page 116

NGT—Technical description (2010)
Pre-driver stage
Drawing
ALTERNATIVE TEXT
The levelled RF from the gain control stage is passed via T201 to the Class A push-pull
amplifier formed by V204 and V205. L202 and C207 provide a small amount of high
frequency gain peaking to ensure the overall gain is flat with frequency.
Drawing 04-03369, or
ALTERNATIVE TEXT
Drawing
The levelled RF from the gain control stage is passed via T201 to the Class A push-pull
amplifier formed by V204 and V205. L202 and C207 provide a small amount of gain
peaking to ensure the overall gain is flat with frequency.
Driver stage
Drawing
ALTERNATIVE TEXT
The signal from the pre-driver stage goes via T202 to the driver stage. The driver is a
Class B push-pull amplifier that provides a voltage drive to the output stage.
Each side of the amplifier has three transistors in parallel (V207, V208 and V209, and
V210, V211 and V212). These transistors have resistors on their emitters to force them to
share the load.
The bias for the driver stage, provided by the emitter follower V206 and set by R222
(DR. BIAS), is applied to the centre tap of T202.
Drawing
ALTERNATIVE TEXT
The signal from the pre-driver stage goes via T202 to the driver stage. The driver is a
Class B push-pull amplifier that provides a current drive to the output stage.
V207 and V208 have collector to base feedback to flatten the gain. R273 balance control
varies the gain slightly in V208, which is used to balance the second harmonic (see
page 185, Adjusting balance
The bias for the driver stage, provided by V214 and V206, and set by R222 (DR. BIAS),
is applied to the centre tap of T202.
Drawing
ALTERNATIVE TEXT
The signal from the pre-driver stage goes via T202 to the driver stage. The driver is a
Class B push-pull amplifier that provides a current drive to the output stage.
V207 and V208 have drain to gate feedback to allow balance adjustment to the second
harmonic (see
The bias for the driver FET is provided to each gate individually via R222 (DR BIAS 1)
and R235 (DR BIAS 2) from the temperature-compensated reference IC201/A.
82
04-03169
04-03542
04-03169
04-03369
control).
04-03542
page 185, Adjusting balance control).
NGT Transceiver System Technical Service Manual