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2.
Circuit Description
2.1 Configuration and Outline
The cabinet of the JRL-2000F consists of a front panel, a top cover, a bottom cover, a
rear panel and a main chassis.
.
The equipment of the cabinet consists of the following five units:
The operation of each unit will be described below. Refer to the External View (page
30) for the general configuration and Print Circuit Board Layout (page 55) for the parts
layout of the unit, respectively.
Unit Name
Power amplifier
Power supply unit
Matching circuit
Antenna switch
Control
Switch panel
Display
2.2
NAH-232
Power
Amplifier Unit
Installation Position
At the bottom of the main chassis on the righted side
At the bottom of the main chassis on the left-hand side
Upper part of the main chassis
Upper part of the rear panel
Upper part of the main chassis
Front panel
This unit is attached to the lower part of the main chassis on the righthand side. It
amplifies the drive input power sent from the exciter up to the rated output power by
the wide-band linear power amplifiers.
This unit consists of two CAH-377 power amplifiers attached to each heat sink respec-
tively, a CCB-367
PA
control circuit attached to the upper side of the heat sink, a
CFF-
361 power combiner circuit attached to the bottom side of the heat sink, and a cooling
fan.
2.2.1
CAH-377
Power
Amplifier
CAH-377 power amplifier consists of two identical wide-band linear amplifers which
operate independently of each other on the printed circuit board. Each wide-band
amplifier has 12 RF power MOSFETs and amplifies a 20 W PEP input power to 250W
PEP.
The RF power MOSFET is new generation's power device which has excellent resis-
tance to thermal stress and reflected power, a high linearity and a low high-order
intermodulation distortion(lMD), as compared with the conventional bipolar transistor.
As the two wide-band linear amplifiers have the same circuit, the circuit operation will
be described for the left part of the connection diagram on page
39.
The input power signal from J1 is sent to the input transformer T I , and divided into
two signals with 180" phase difference.
4
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