JRC JRL-2000F User manual

HF LINEAR AMPLIFIER
JRL-2000F
Service Manual
( .J RC) dapan Radio Co., .fld.

IPreface
This manual provides information required for maintenance and troubleshooting proce-
dures of the JRL-2000F. Refer to the instructions manual for operation.
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I Contents
Preface ______________________________ -_ ________ _; __ ;.. _____________ ..:_;.. _______ ~---'--------------------~-----1
1. Specifications -------------------------------------------------------------------------------------3
2. Ci rcu it Description -------------------------------------------------------------------------------4
2.1 Gonfiguration and Outline -------------------------------------------------------------------4
2.2 NAH-232 Power Amplifier Unit
--------------~----------------------------------------------4
2.2 .1 CAH-377 Power Amplifier ---------------------------------------------------------------4
2.2.2 CCB-367 PA Control ---..:------------------------------------------------------------------6
2.2.3 CFF-361 Power Combiner---------------------------------------------------------------9
2.3 NBL-169 Power Supply Unit----------------------------------------------------------------9
2.3.1 CSA-222 Relay Circuit--------------------------------------------------------------------1 0
2.3.2 CBB-13 Power Factor Corrector -------------------------------------------------------1 0
2.3.3 CBG-68 Main
PS Unit --------------------------------------------------------------------11
2.3.4 CFR-1 02 Noise Filter ---------------------------------------------------------------------12
2.4 CFG-111 Matehing Circuit ------------------------------------------------------------------12
2.5 CSC-433 Antenna Switch -------------------------------------------------------------------14
2.6 CDJ-1143 Control Crcuit --------------------------------------------------------------------15
2. 7 Automatie Tuning-----------------------------------------------------------'-------------------17
2.8 CML-334 Display ------------------------------------------------------------------------------20
2.9 CSD-387 Switch Panel ----------------------------------------------------------------------20
3. Troubleshooting ----------------------------------------------------------------------------------21
4. Cantirrnation of Operation and Readjustment --------------------------------------------26
4.1 Outline -------------------------------------------------------------------------------------------26
4.2 Adjustment of 2 PA Units--------------------------------------------------------------------26
4.2.1. Adjustment of Heat Sensor--------------------------------------------------------------26
4.2.2 Adjustment of ldling Current ------------------------------------------------------------27
4.3 Adjustment
of Power Supply Unit ---------------------------------------------------------28
4.3.1 Adjustment of Output Valtage ----------------------------------------------------------28
4.4 Total Adjustment ------------------------------------------------------------------------------28
4.4.1 Adjustment of Meter-----------------------------------------------------------------------28
4.4.2 Adjustment of APC Circuit ---------------------------------------------------------------29
4.4.3 Adjustment of ALC Circuit ---------------------------------------------------------------29
4.4.4 Adjustment of the VSWR Meter--------------------------------------------------------29
5. External View --------------------------------------------------------------------------------------30
6. Block Diagram ----------------------------------------------------''"-------------------------------34
7. Connection Diagram ----------------------------------------------------------------------------37
8. Print Circuit Board Layout ---------------------------------------------------------------------55
9. Replacement Parts List ------------------------------------------------------------------------72
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1. Specifications
Operating frequency
bands :1.8 MHz band 1.800 to 2.000 · MHz
3.5 MHz band 3.500 to 4.000 MHz
7 MHz band 7.000 to 7.300 MHz
10 MHz band 10.100 to 10.150 MHz
14 MHz band 14.000
to 14.350 MHz
18
MHzband 18.068 to 18.168 MHz
21 MHz band 21.000 to 21.450 MHz
24 MHz band 24.890
to 24.990 MHz
28 MHz band 28.000 to 29.700 MHz
Rated output power :SSB 1
kW PEP* 100% duty cycle; 24 hour.
CW 1
kW* 100% duty cycle, 24 hour.
FSK/SSTV 1 kW* 100% duty cycle, 1/4 hour.
Output impedance
:50 Q unbalanced, VSWR 3.0 (16.7 to 150 Q)
Harmonics :-60 dB or less
Intermodulation
distortion (IMD) :-35 dB or less below PEP (at 1 kW output)
Input impedance :SOQ unbalanced
Exciting power :1 OOW max.
Frequency switching
time : Less than 0.1 sec.
Power supply valtage : 85 to 264 V AC, single-phase
Power consumption :2.5 kVA or less (at 1 kW output)
Input power factor :95% or more (at 1 kW output)
Temperature range :-1
ooc to 40°C
Protection circuits :PA excess current;
PA overheat; PA abnormal Ioad;
AC power supply excess valtage; power supply overheat;
PA failure; excessive antenna VSWR; exciting power
excess; and antenna matehing anomaly.
Dimensions :430(W) X 300(h) X 402(0) mm
Weght : Approx. 28Kg
* Note :Rated output on 200 to 240V AC. The rated output power on 100 to 120V AC is 750W PEP.
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·12. Circuit Description
2.1 Gonfiguration and Outline
The cabinet of the JRL-2000F consists of a front panel, a top cover, a bottarn cover, a
rear panel and a main chassis.
The equipment of the cabinet consists of the following five units:
Unit Name Installation Position
Power amplifier At the bottom of the main chassis on the righted side
Power supply unit At the bottom of the main chassis on the left-hand side
Matehing circuit Upper part of the main chassis
Antenna switch Upper part ofthe rear panel
Control Upper part of the main chassis
Switch panel
Display Frontpanel
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
Iayout of the unit, respectively.
_, 2.2 NAH-232 Power Amplifier Unit
This unit is attached to the lower part of the main chassis on the righthand side. lt
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 bottarn 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-b~md 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 tothermal stress and reflected power, a high linearity and a low high-arder
intermodulation distortion(IMD), 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 inputpower signal from
J1 is sent to the input transformer T1, and divided into
two signals with 180° phase difference. 4
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C1,-C2, es, R1 and R2 compose of a circuit which matches an input imped~nce.-
T11 and T21 are transformers which insulate the exdtation signal from ground Ievei.
Thetwo excitation signals are consumed by R17 to R20 and R27 to R30 which are the
gate terminating resistors of the RF power MOSFET.
As a RF has the insulated gate, it can be assumed that only the equivalent
inpuf
capacitance exists between gate·and source~
The gate terminating resistor shunts this input capacitance.
The RF power MOSFET
TR11 to TR16 are connected parallel. They are excited by
the signal voltage at both ends of the gate terminating resistor and they amplify the
output currentin a half cycle. On the other hand, TR21 to TR26 amplify the output
current in another half cycle. Theseoutput currents
of half-cycles are fed to the pri-
mary winding
of the output transformer TS and the current waveform of full-cycle is
composed. These output currents flow to the Ioad circuit via output terminal J4. ·
As a result, the upper part of the output voltage waveform is amplified by
TR11 to
TR16,and the lower part by
TR21 to TR26. -
The SEPP circuit, in contrast to the transformer-coupled push-pull circujt, seldom
generates a phase difference when composing output waveforms. Therefore, a wave-
form with less distortion can be obtained.
The transformer T3 provides a gate-bias voltage to the RF power MOSFET for the
operation in class AB.
A
DC bias valtage of approx. 2.5 V is provided through T3 to each RF power MOSFET
from CCB-367 PA control circuit. The resistors
R61 and R62, connected betweenthe
third winding
of T3 and the second winding of the input transformer T1, work as a
negative feedback.
(Note): The chips with same charasteristics are packaged to the RF power MOSFET
2SK408 and 2SK409. However, the Iead Iayout differs.
2SK408
2SK409
IDimensions in mml
2SKUJ8
2SK409
(JEDEC T0-220AB)
l.C:.te I.
Orai"
2. :ioura Z. Source
l. CaiA!
Fig.1
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2.2.2 CCB-367 PA Control
CCB-367 PA control is attached to the upper s.ide of the power amplifier unit and is ·
equipped with a bias voltage control circuit for,the two power amplifiers, a cooling fan
control circuit, protection circuits and an inputpower splitter.
1)Power Amplifier Bias Voltage Control Circuit -
As the RF power MOSFET
of CAH-377 power amplifier operates in class AB, the DC
bias voltage which determines the operating point current (idling ct.irrent) is
ess~ntial.
The gain of the power amplifier can be changed by changing the DC bias voltage.
!he normal bias voltage is about 2.5V DC. However, the bias voltage varies accmd-
ing to the KEY signal state or.
the. temperature change of the heat sink to get the
optimum gain of the power amplifier. · ·
IC4(1/4 to 4/4) and IC5(1/4 to 4/4) are DC amplifiers which send out a bias voltage to
the RF power MOSFET block of each SEPP circuit. This
biasvoltage can be adjusted
with variable resistors
RV11 to RV14 and RV21 to RV24. The reference voltage for
this bias voltage
is obtained from the developed voltage between the base and the
emitter of
TR1 and TR2. TR1 and TR2 are attached to the side part of the heat sink of
CAH-377 power amplifier. As the base-emitter is driven by a constant current, the
base-emitter voltage depends.on the temperature of the heat sink. .
The base-emitter voltage is amplified by the DC amplifier IC3 (4/4) and sent to each
poweramplifier block
as abias voltage.
As the RF power MOSFET, employed in the JRL-2000F, has a negative thermal.
coefficient, the gain decreases when the temperature of the heat sink rises. To com-
pensate this,
TR1 and TR2 check the temperature of the heat sink and operate to
keep the gain constant, regardless of the temperature change,
by controlling the bias
voltage. ·
The comparator IC3 (3/4) controls the bias voltage by referencing the KEY signal.
Fig.2 shows each waveform of the signal voltage.
KEY &
PTI signal ®from outside, passes the time-constant circuit composed of C1
and R2, and is switched by the comparator. The comparator output @, sent out from
No.14 pin of IC1, passes the time-constant circuit composed of
RS, CD14 and C2, and
the DC amplifier IC3 (4/4) and then is formed to a signal voltage waveform
@.
The signal voltage waveform ©is applied to the DC amplifiers IC3 (3/4) and IC (4/4),
and controls the bias voltage
of each power amplifier bloq_k. The bias voltage @varies
according to the KEY & PTT signal.
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'. /
OFF
OFF
0- H I
r-
KEY &PTT signal L
ON
ON
@ No.14 pin of IC1 (3/4)
SV
L
ov
~--~-~-
SV
@ No.8pinofiC3(1/4) ( \ ( L
ov
2.SV
@ Bias voltage of ( ( L
each PA
ov
Fig.2
2)APC (Automatie Power Control) Circuit
The APC circuit prevents excessive output by controlling the bias voltage of the power
amplifier when the output
of the linear amplifier exceeds the rated value.
The outputpower signal Vf, detected by the CFG-111 matehing circuit, is fed to the
comparator
IC1 (4/4) and compared with the reference voltage adjusted by the vari-
able resistor RV3.
When the Vf signal exceeds therated value, the comparator is turned on and the
comparator output voltage controls IC3 (3/4) and IC3 (4/4) (DC amplifier to control the
bias voltage). As a result, the bias voltage drops and the outputpower is controlled to
be constant in
cas-e of excessive output.
When the comparator
is on, the OVER DRIVE signal is sent to the switch panel via
diode CD1, and lights up the DRIVE LED in red.
3)Temperature Detector Circuit.
The base-emitter voltage of the temperature detector transistor
TR1 and TR2 attached
-to each of the two heat sinks is compared by the comparator IC6 (1/4) and IC6 (2/4),
and IC6 (3/4) and IC6 (4/4), respectively.
-.
As TR1 and TR2 have a negative temperature coefficient of about -4.5 mV/ oc (de-
gree centigrade) the base-emitter voltage drops when the temperature ofthe heat
sink rises.
Variable resistors
RV1 and RV2 set the reference voltage of the comparators IC6 (2/4)
and IC6 (4/4) to the base-emitter voltage which corresponds to the temperature of 80
oc of the heat sink.
At this time, the reference voltage of the comparators IC6 (1/4) and IC6 (3/4) is the
same as that which corresponds to the voltage when the temperature of the heat sink
is 50 oc. Therefore, when the temperature of the heat sink exceeds 50 oc, the com-
parator IC6 (1/4) or IC6 (3/4) is turned on, and "High" Ievei voltage is applied.
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to turn onthe transistor TR3 and the eooling fan starts to rotate. ·
When the temperature of the heat sink exeeeds 80
oc, the eomparator IC6 (2/4) or
IC6(4/4) turns on.
At this time a Low Ievei PA HEAT alarm
signai is sent to the CDJ-1143eontrol eireuit
via diode CD?.
When the PA HEAT alarm is issued, the JRL-2000F displays "A3".
4)PA UNBL Alarm Deteetor Cireuit
The CFF-361 power eombiner is equipped with a sensor R7 whieh deteets unbalaneed
power when the power is eombined.
This sensor deteets the unbalaneed power and when the terminal valtage of the sen-
sor inereases, the eomparator
IC1 (2/4) turns on, and the PA BL alarm signal is gener-
ated.
When the PA BL alarm
is issued, the JRL-2000F displays "A4".
S)PA LOAD Alarm Deteetor Cireuit.
The CFF-361 power eombiner is equipped with a cireuit whieh deteets Vf and Vr
of
the PA output terminal.
Vf and Vr are eompared
by the eomparator IC2 (2/4).
When the VSWR value exeeeds 3.0 at the PA outputterminalbeeause of a poor
matehing situation with the matehing eireuit, the ratio
VrNf exeeeds 0.5 and the eom-
parator IC2 (2/4) ehanges from Low Ievei to High Ievei.
This eomparator output signal triggers the flip-flop cireuit eomposed of IC2 (3/4) and
IC2 (4/4), and turns over the output voltage to issue the PA
LOADalarm signal.
When the PA LOADalarm is issued, the JRL-2000F displays "A9",
IC2
(1 /4) and the peripheral deviees eompose of a cireuit whieh resets the flip-flop.
6)PA OFF Cireuit
When one of the three alarm signals of the PA eontrol beeomes Low Ievei, or when
PA OFFsignal whieh foreedly turns off the power amplifier beeomes Low Ievei be-
eause of the operation of the other proteetion eireuit, a Low Ievei signal is sent to the
· inputterminal of the eomparator
IC1 (4/4) via CD4 or CD6 diode OR eireuit and the
output of
IC1 (1/4) turns from Low Ievei to High Ievei. '
This signal is applied to the DC amplifier whieh eontrols the bias voltage ofthe power
amplifiers IC3 (3/4) and IC3 (4/4), and the bias voltage of the power amplifiers is set to
-9V.
lfthe bias voltage beeomes -9V, the RF power MOSFET of the power amplifier is eut
off and the output power beeomes 0
W, regardless of the existenee of the exeitation
power.
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: .... _ ... )
?)Power Splitter Circuit
The excitation power supplied to J201 terminal from the exciter is applied to the
RF
transformer T1 via -2dB attenuator circuit. ·
T1 is an impedance convert transformer (50 ohms : 12.5 ohms).
The excitation power
is distributed to each t~rminal P21 to P24.
2.2.3 CFF-361 Power Combiner
The CFF-361 power combiner is attached to the bottarn of the power amplifier unit.
. This circuit generates a 1kW PEP
by combining the output power from the power
amplifier of the four SEPP circuits.
These power amplifier output currents are combined by the RF transformers
T1 and
T2, and finally combined by T3.
As the output impedance of T3 is 12.5 ohms, the step-up transformer T4 is converted
to 50 ohms.
Resistcrs
R1, R2 and R3 absorb the unbalanced power generated at both ends of
each combining transformer.
R3 is equipped with a sensor R7 which detects temperature.
When a large unbalancing power is generated among these four power amplifier,
R3
produces heat to increase the resistance of R7 and the PA BL alarm circuit is acti-
vated.
The circuit, consisting
of a current transformer T5, diedes CD1 and CD1, capacitors
C1 to C4 and resistors R51 to R54, detects Vf and Vr of the poWer combiner output
terminal.·
Vf and Vr issue the PA LOADalarm when the VSWR of the power combiner output
terminal
is 3.0 or more.Relay K4 is turned on when the PA switch is on, and the com-
bined power
is sent to the matehing circuit through this relay .
2.3 NBL-169 Power Supply Unit
The NBL-169 power supply unit is a regulated switching power supply whose power
output of DC 80 V is generated using AC 100 V to 240
V. Because the pulse-shaped
current flows to capacitors in a smothing circuit in a power supply unit with a capaci-
tor-inputtype smothing circuit, the power factor of AC input is, in general, about 0.5 to
0.6.
The JRL-2000F has employed
apower factor corrector circuit in the formerstage of
the switching regulator circuit to obtain a power factor of approx.1. ·
The CBB-13 power factor corrector is attached to one side of the heat sink which is in
the center of the unit, and the CBG-68 main PS unit
is attached to the other side. The
unit also incorporates a switching power supply unit which generates a
DC +12 V (4A)
power supply for the control circuit.
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