Tokyo Hy Power Labs HL-550FX 550W HF LINEAR AMPLIFIER User Manual
Tokyo Hy-Power Labs, Inc. 550W HF LINEAR AMPLIFIER Users Manual
Users Manual
Users Manual
Solid-State HF/50MHz Band
550W Linear Power Amplifier
Model HL-550
FX
1
1. Introduction
Thank you for purchasing the HL-550
FX
.
This compact and lightweight desktop HF linear power amplifier has a maximum input
power of 1.2kW. Our solid-state broadband power amp technology makes it the smallest
and lightest in the industry in its class.
Typical output power is 550W (SSB, CW) with the drive power of 65-90W.
It is best suited for the DX-pedition use due to its light and compact design.
2. Cautions
2-1 The amplifier is cooled by forced airflow. Several inches of clearance on the top
and the rear wall are necessary to allow for smooth air intake into the fan. Do not
block the air vents on the top cover.
2-2 Keep the amplifier out of direct sunlight, in a cool dry environment.
2-3 Internal high voltages (AC, DC and RF), are present at all times, ON AIR or OFF.
Internal access should be limited to avoid injury.
2-4 Turn off the AC main power immediately upon any unusual sounds, sights, or
odors. Check the multimeter readings of Vd and Id, the fuses and all cable
connections around the amplifier. Please notify the dealer or the factory of any
problems.
2-5 For your safety, do not operate the amplifier without adequate grounding. A
proper ground connection will result in peak performance and stability, in
addition to reduced RF strays or noises.
2-6 To eliminate the RF interference to such home appliances as TV, FM radio,
telephone sets, and etc., it is recommended that clamp-on ferrite cores be
inserted at both ends of the remote control cable, ALC cable, coaxial jumper cable,
and antenna cables, as needed. Also, a common mode AC line filter (near the AC
outlet), and in-line low pass filters on the antenna coaxial cable (as necessary),
are recommended.
2
2-7 The amplifier has fast acting sophisticated protection circuits. Please note,
however, any such actions that cause the same fault to occur repeatedly, will lead
to failure of the valuable final power FET transistors.
2-8 Before checking inside the amplifier, be sure to wait a few minutes for the high
DC voltage to discharge (monitor Vd meter reading). The potentiometers for RF
power detector, protection circuits, FET bias voltage circuit, etc., are precisely
adjusted at the factory, and should not be altered. Doing so, would require
readjustment with precision measuring instruments.
2-9 The DC power supply section consists of most efficient and sophisticated
switching mode circuit. It accepts the wide AC line voltages ranging from AC
100V up to 260V. Since the line voltage is detected and selected automatically,
you do not have to worry about the tap change of internal power transformer
whichever country you will travel. Be sure to verify capacity of AC line fuse
before you plug the AC power cord into the outlet.
2-10 Before starting the amplifier, be sure to connect a dummy load (50 ohms, 550W
min.) or a well-adjusted antenna to the output terminal. Operating without any
load will cause extreme stress to the RF power FET’s, although protection
circuits should work under critical conditions.
2-11 Required drive power is slightly less than 100W to obtain the full 550W output.
Do not attempt to operate with excessive drive from a high power transceiver.
2-12 Keep the aluminum heat sink and air openings free from dust and blockages.
Periodic cleaning will prevent degraded cooling efficiency.
2-13 For long continuous operation in RTTY/FM modes, it is recommended that you
reduce the RF drive levels by 20% to 30% lower output than CW/SSB modes.
2-14 To prevent damage to the precision electronic components, avoid extreme
physical shock to the amplifier. If factory service is required, the amplifier should
be shipped using the original box and packing materials.
3
3. Features
3-1 Our solid-state broadband design engineers worked to make the HL-550FX, the
lightest and most compact 550W out portable HF/50MHz amplifier in the
industry. This world-class compact 550W HF amplifier is the easiest to handle
and operate anywhere in the world.
3-2 The amplifier’s main PA section includes 4 high power MOS FET VRF150,
resulting in 550W (SSB/CW max.) on HF and 50MHz bands. The amplifier’s
broadband characteristics require no further tuning once the operating band is
selected.
3-3 The amplifier allows operation in full break-in CW mode due to the use of the
amplifier’s high-speed antenna relays (made by Panasonic).
3-4 With the unique duct structure design and the powerful blower fan, the
aluminum heat sink block for RF PA module (and other components), are
effectively cooled. The fan’s quiet operation allows for even the weakest DX
signals to be heard.
3-5 The amp utilizes a sophisticated circuit to run the various high speed protection
circuits such as overdrive, high antenna SWR, DC overvoltage, band miss-set etc.
3-6 This amplifier is compatible with wide AC line voltage ranging from AC 100V to
260V. Although AC line voltage is automatically selected, be sure to install proper
fuse into AC line fuse holder.
3-7 For the safety of the operator, an Interlock system is employed. The AC power is
shut down if the top cover is removed, and the automated safety interlock is
activated.
3-8 An analog multimeter allows the operator to monitor Pf (Forward output power),
Pr (Reflected power), Vd (Drain voltage of power FET), Id (Drain current) etc.
4
4. Specifications
Frequency Band 1.8~50 MHz all amateur bands including WARC bands
Mode SSB, CW (RTTY)
RF Drive 65~90W typ. (100W max.)
Output Power 550W typ. (RTTY 400W max.)
Drain Voltage 42V
Drain Current 30A max.
Input Impedance 50Ω (unbalanced)
Output Impedance 50Ω (unbalanced)
Final Transistor VRF150 x 4
Circuit Class AB parallel push-pull
Cooling Method Forced Air Cooling
Output Power Pf 1kW
Reflected Power Pr 100W
Drain Voltage Vd 60V
Multi-meter (F.S.)
Drain Current Id 50A
Input/Output Connectors
UHF SO-239
AC 200~260V, 50/60Hz 7.5A max. AC Power
AC 100~130V, 50/60Hz 15A max.
AC Consumption 1.3kVA max. when TX
Dimension 232 x 145 x 392 mm, 9.1 x 5.7 x 15.4 inches (WxHxD)
Weight Approx. 9.2kgs. or 20.3lbs.
Accessories AC Power Cord x 1
Coax Jumper Cable (with PL259’s) x 1
RCA Plug x 2
Spare Fuse 8A x 2 (for AC200V line)
Spare Fuse 15A x 2 (for AC100V line)
Spare Fuse 15A x 2 (for F202, F203 of PC1662V power amp board)
Spare Fuse 1A x 1 (for PC1662V power amp board) (miniature fuse)
Spare Fuse 3.2A x 1
(for PC1819 sub AC control board) (miniature fuse)
Users Manual
5
5. AC Line Voltage
5-1 Although the amplifier is designed to work with both AC 115V (100-130V) and
AC 230V (200-260V), for stability we recommend operation from AC 230V.
5-2 The correct AC plug (not included in the package) must be obtained locally due
to the AC plug variations worldwide.
5-3 The AC line fuse has been factory preset for 115V use (or as requested by the
customer at the time of order). If you wish to change to AC 230V, change the fuse
to 8A. For your safety, before making this change, be sure to pull the AC plug
from the AC outlet to avoid injury.
NOTICE
Please note the followings when you are using
AC100V line (AC100V~120V).
NEVER EXCEED OUTPUT POWER OF 500W,
WHEN RUNNING THE AMP FROM AC100~120V LINE.
Otherwise, over-current protection completely shuts down the drain voltage power
supply for five minutes before it gets resettable.
When this protection works, O.DRIVE lamp lights and HL-550FX will enter the through
state, the reset of the amp being disabled for five minutes.
To restart the amp, turn the POWER switch OFF, and wait for 5 (five) minutes. Then
turn the power ON.
If the protection works too often, please take one or all of the following measures.
① Lower the drive power of the transceiver.
② Connect the ALC line. Adjust the ALC Output Adjustment Knob on the rear panel
so that the drain current (ID) will never exceed 25.0A on any frequency.
③ Change to AC200~240V line.
6
6-A. Front Panel Description
P
PP
PO
OO
OW
WW
WE
EE
ER
RR
R
O
OO
OF
FF
FF
FF
FS
SS
ST
TT
TB
BB
BY
YY
Y
O
OO
OP
PP
PE
EE
ER
RR
R.
..
. O
OO
ON
NN
N A
AA
AI
II
IR
RR
R O
OO
O.
..
.D
DD
DR
RR
RI
II
IV
VV
VE
EE
EO
OO
O.
..
.V
VV
VO
OO
OL
LL
LT
TT
TF
FF
FU
UU
US
SS
SE
EE
E O
OO
O.
..
.H
HH
HE
EE
EA
AA
AT
TT
TP
PP
PR
RR
R
B
BB
BA
AA
AN
NN
ND
DD
DM
MM
ME
EE
ET
TT
TE
EE
ER
RR
R
P
PP
PR
RR
RO
OO
OT
TT
TE
EE
EC
CC
CT
TT
T
F
FF
FA
AA
AN
NN
N
I
II
ID
DD
D
F
FF
FX
XX
X
M
MM
MO
OO
OD
DD
DE
EE
EL
LL
L
T
TT
TO
OO
OK
KK
KY
YY
YO
OO
O H
HH
HY
YY
Y-
--
-P
PP
PO
OO
OW
WW
WE
EE
ER
RR
R
S
SS
SO
OO
OL
LL
LI
II
ID
DD
D S
SS
ST
TT
TA
AA
AT
TT
TE
EE
E L
LL
LI
II
IN
NN
NE
EE
EA
AA
AR
RR
R A
AA
AM
MM
MP
PP
PL
LL
LI
II
IF
FF
FI
II
IE
EE
ER
RR
R
1
11
12
22
2 3
33
3 4
44
45
55
5 6
66
6 7
77
78
88
89
99
9
1
11
10
00
0
1
11
11
11
1
1
11
12
22
2
1
11
13
33
31
11
14
44
4
H
HH
HL
LL
L5
55
55
55
50
00
0
①
①①
①POWER
POWERPOWER
POWER : Main power switch to turn AC power on and off.
②
②②
②POWER
POWER POWER
POWER
(LED)
(LED)(LED)
(LED)
: Green LED lights when power is turned on.
③
③③
③OPER
OPEROPER
OPER.
..
. : OPERATE/STAND-BY switch. At OPERATE, the amplifier is ready to
go into ON AIR (TX) mode and at STBY, it is on STAND-BY mode.
④
④④
④ON AIR
ON AIRON AIR
ON AIR
(LED)
(LED)(LED)
(LED)
: Green LED lights when the amplifier is in transmit (TX) mode.
⑤
⑤⑤
⑤O.DRIVE
O.DRIVEO.DRIVE
O.DRIVE
(LED)
(LED)(LED)
(LED)
: When overdrive or band miss-set is detected, LED lights to indicate
the protection circuit has worked.
⑥
⑥⑥
⑥PR
PRPR
PR
(LED)
(LED)(LED)
(LED)
: LED lights when reflected power from antenna exceeds 70W to
indicate protection circuit has worked.
⑦
⑦⑦
⑦O.VOLT
O.VOLTO.VOLT
O.VOLT
(LED)
(LED)(LED)
(LED)
: When the DC drain voltage of the FET (Vd) is too high, the LED lights
to indicate the protection circuit has worked.
⑧
⑧⑧
⑧FUS
FUSFUS
FUSE
EE
E
(LED)
(LED)(LED)
(LED)
: LED lights when the 15A glass fuse has blown from excessive Id.
(Two fuses are on the PC1622V PA board.)
7
⑨
⑨⑨
⑨O.HEAT
O.HEATO.HEAT
O.HEAT
(LED)
(LED)(LED)
(LED)
: When the PA module temperature reaches 80 deg.C, the LED lights to
indicate the protection circuit has worked. (It is necessary for the
cooling fan to operate for several minutes to cool the PA module.)
(Turn the main POWER switch to off, and then on again to reset the Protection Circuits.)
(Turn the main POWER switch to off, and then on again to reset the Protection Circuits.)(Turn the main POWER switch to off, and then on again to reset the Protection Circuits.)
(Turn the main POWER switch to off, and then on again to reset the Protection Circuits.)
⑩
⑩⑩
⑩BAND
BANDBAND
BAND
: Select the desired operating frequency band.
⑪
⑪⑪
⑪METER
METERMETER
METER
: To change the multi-meter scales. Meter reads Pf, Pr, Vd, and Id.
⑫
⑫⑫
⑫ID
ID ID
ID
(LED)
(LED)(LED)
(LED)
: LED lights when the input drain current is over 20A. This does not
mean that any damage occurred to the amplifier, but is useful for the
user to notice any stress influencing the final FET caused by high drain
current, load impedance trouble, etc. We recommend that you note the
usual condition of the lighting. When any unusual symptoms are
noticed, the user may lower the drive power from the transceiver, check
the antenna SWR, etc.
⑬
⑬⑬
⑬FAN
FAN FAN
FAN
(LED)
(LED)(LED)
(LED)
: LED lights when fan is running at high speed. When the heatsink
reaches 50℃ the cooling fan will switch to high-speed mode to cool the
heatsink.
⑭
⑭⑭
⑭
MULTIMETER
MULTIMETERMULTIMETER
MULTIMETER
: Pf (Forward output power), Pr (Reflected power from antenna), Vd
(FET drain voltage), and Id (FET drain current) are shown on the scale
as selected by ⑪METER select switch.
8
6-B. Rear Panel Description
A
AA
AL
LL
LC
CC
C
A
AA
AL
LL
LC
CC
C A
AA
AD
DD
DJ
JJ
J
S
SS
ST
TT
TB
BB
BY
YY
Y
G
GG
GN
NN
ND
DD
D
A
AA
AN
NN
NT
TT
T
A
AA
AC
CC
C
F
FF
FU
UU
US
SS
SE
EE
E
I
II
IN
NN
NP
PP
PU
UU
UT
TT
T
⑭
⑭⑭
⑭AC POWER
AC POWERAC POWER
AC POWER
: AC Mains Socket. Socket for the AC power cord. (Socket is EMI
filtered.)
⑮
⑮⑮
⑮STBY
STBYSTBY
STBY : RCA Jack. Connect the control cable from the ACC terminal (or SEND,
TX GND etc.) of the transceiver. The center pin is to be shorted to
ground through the relay circuit of the transceiver. The DC current
necessary is 5V, 1mA only.
⑯
⑯⑯
⑯ALC
ALCALC
ALC
: RCA Jack for ALC Voltage Output. Negative DC voltage appears at the
center pin, which is fed back to the ALC terminal of the transceiver.
ALC is used to keep the amplifier output power at certain limits. Also it
is useful when the transceiver output power is higher than 100W.
(See page 12, 8.ALC Connection). Also consult your HF/50MHz
transceiver’s user manual.
⑰
⑰⑰
⑰GND
GNDGND
GND
: Ground Terminal
⑱
⑱⑱
⑱ALC ADJ
ALC ADJALC ADJ
ALC ADJ
: Potentiometer to adjust ALC voltage level. Minus 10V is available at
maximum, when turned full counter-clockwise.
Factory setting is 0 volts, with the pot turned full clockwise.
⑲
⑲⑲
⑲FUSE
FUSEFUSE
FUSE : A pair of fuses for AC mains. 15A glass pre-installed fuse. (Change to
8A fuses if 230V line is used.)
⑳
⑳⑳
⑳IN
ININ
IN
PUT (TX)
PUT (TX)PUT (TX)
PUT (TX) : RF Input Connector. Connect the coax jumper cable from the
transceiver.
○
○○
○
21
2121
21
ANT
ANT ANT
ANT (OUTPUT)
(OUTPUT)(OUTPUT)
(OUTPUT) : RF Output Connector. Connect the coax cable to the antenna.
9
Inner Layout of
Inner Layout ofInner Layout of
Inner Layout of HL
HL HL
HL-
--
-550
550550
550FX
FXFX
FX
Upper View
Upper ViewUpper View
Upper View
① RF Power Detector and Send-Receive Switching Relay
② Inter-lock Switch
③ LPF Board
④ Main Power Source Unit
⑤ Sub-Power Source Unit
⑥ Control Board
⑦ Power Amp Unit
⑧ Frequency Detector Board
⑨ Cooling Fan
⑩ AC Fuse
10
7. Connection and Operation
This section explains a one-antenna system connected to the transceiver and an external
SWR/POWER meter.
7-1 Connect AC cord and coax cables as illustrated above. Connect the cable from
“SEND” to ACC or the remote terminals of transceiver, where it is marked
“SEND” or “TX GND”. These terminal pins are shorted to the ground when the
transceiver is in TX/ON AIR mode. If these connections are not made, the
amplifier will not go into TX (amplification) mode. For a temporary check to the
amp, ground the STBY center pin by inserting an RCA plug whose center pin has
been soldered to the outer case of the plug with a small piece of wire.
7-2 At first, turn the ALC knob full clockwise to avoid ALC voltage being fed to the
transceiver. Application of ALC will be covered in the following Section 8. ALC
CONNECTION.
7-3 Keeping the POWER (AC mains) switch off, check the SWR of your antenna by
keying the transceiver to TX mode (CW or RTTY mode). Monitor the SWR with
an external SWR/Power meter. If SWR is 1.5 or higher at band center, the
A
AA
AL
LL
LC
CC
C A
AA
AN
NN
NT
TT
T
(
((
(S
SS
SE
EE
EN
NN
ND
DD
D,
,,
,T
TT
TX
XX
X G
GG
GN
NN
ND
DD
D)
))
)
A
AA
AC
CC
CC
CC
C
I
II
IN
NN
NP
PP
PU
UU
UT
TT
T
A
AA
AN
NN
NT
TT
T
S
SS
ST
TT
TB
BB
BY
YY
YA
AA
AL
LL
LC
CC
C
A
AA
AC
CC
C
T
TT
TX
XX
XA
AA
AN
NN
NT
TT
T
T
TT
T R
RR
R A
AA
A N
NN
N S
SS
S C
CC
C E
EE
E I
II
I V
VV
V E
EE
E R
RR
RA
AA
A N
NN
N T
TT
T E
EE
E N
NN
N N
NN
N A
AA
A
H
HH
H L
LL
L -
--
- 1
11
1 .
..
. 1
11
1 K
KK
K F
FF
F X
XX
X R
RR
R E
EE
E A
AA
A R
RR
R S
SS
S I
II
I D
DD
D E
EE
E
S
SS
S W
WW
W R
RR
R /
//
/ P
PP
P O
OO
O W
WW
W E
EE
E R
RR
R M
MM
M E
EE
E T
TT
T E
EE
E R
RR
R
K
KK
K
F
FF
F
X
XX
X
R
RR
R
E
EE
E
A
AA
A
R
RR
R
S
SS
S
I
II
I
D
DD
D
E
EE
E
K
KK
K
F
FF
F
X
XX
X
R
RR
R
E
EE
E
A
AA
A
R
RR
R
S
SS
S
I
II
I
D
DD
D
E
EE
E
HL
HLHL
HL-
--
-550FX REAR SIDE
550FX REAR SIDE550FX REAR SIDE
550FX REAR SIDE
11
antenna has to be adjusted for lower SWR. As an alternative, an antenna tuner
may be inserted.
7-4 Turn the POWER switch on. Turn the BAND switch to a desired operating
frequency band. Turn the STAND-BY switch to OPER (operate) position and the
amplifier is ready to go. If you key the transceiver with the carrier level set
relatively low (such as 20-30W), you will achieve an amplified output signal of a
few hundred watts. Monitor this output with the multimeter (at the Pf position)
or with an external power meter. Increase drive level to roughly 50W and see if
the antenna SWR stays constant. (As higher RF currents flow, some antennas
may show a changed SWR value due to heated connector junctions and trap
coils.)
7-5 You can now increase the drive level to nearly 80-90W to achieve maximum
carrier output power of 550W (CW) from the amplifier. If you change to SSB
mode, average voice power of a few hundred watts will be observed on the panel
meter, Pf scale, while peak voice power reaching a little over 550W. For high duty
cycle transmissions like RTTY mode, it is recommended that you reduce the drive
power by some 30%.
7-6 With a high power transceiver in SSB mode, you can overdrive the amplifier
resulting in a distorted output signal. This can occur if you speak too loud or if
you set the microphone gain too high. Speak into the microphone properly to
reduce the possibilities of splattering into the neighborhood. The ALC is effective
in preventing the output signal from being distorted or to limit the carrier level to
within rated output levels. It is strongly recommended to make ALC connection,
especially when 200W out high power radio is used to drive.
7-7 Protection circuits may work during operation depending on the conditions. If the
protection circuit has shut down the amplifier, check the antenna SWR, Vd, AC
line voltage, or try to reduce the drive level. To reset, turn off the POWER switch
once, then back on again. The power transformer has an overheat protection in
the coil layer. If this temperature switch activates, the amplifier will put you in
receive mode with the cooling fan operating until the transformer has cooled off.
It may take ten to fifteen minutes to cool, depending upon room temperature. For
more details on this protection circuit, see Section 9. PROTECTION CIRCUITS.
12
8. ALC Connection
ALC voltage is available at the terminal marked ALC (RCA phono jack) on the right lower
corner of the rear panel. Negative maximum DC voltage of ten volts (-10V) is produced at
this terminal when the amplifier is fully driven. This voltage is adjustable with the ALC
ADJ. knob located above the ALC jack. Setting ALC voltage properly fed back to the
transceiver, we recommend you to keep the maximum output power constant or hold the
power at a certain level. Also ALC is useful in avoiding your SSB signal from being
distorted when overdriven. Depending upon the manufacturer of the transceiver, the
suitable ALC voltage differs. ICOM may need 0~-4V, and Yaesu may need 0~-5V range.
Kenwood may need -6~-8V maximum. Check your transceiver manual.
8-1 Prepare an ALC control cable using RCA plug supplied in the package. Solder a
single wire or (more preferably) a shielded single wire to the center pin of RCA
plug and solder the shield braid to the outer side of the plug. Connect the control
cable to the “ALC (or EXTERNAL ALC)” jack of the transceiver. External ALC
input is sometimes available at one of the pins of the “ACC” socket of the
transceiver as well.
8-2 At first, turn ALC ADJ full clockwise. Drive the amplifier in CW/RTTY mode to
full output power. Then turn the ALC ADJ counter-clockwise. Observe the
SWR/Power meter at the output, (or Pf of the multimeter). Stop turning the ALC
ADJ at the point the power starts to decrease. Or if you wish to further reduce
the power, keep turning ALC ADJ until the desired level is achieved. If you
further try to increase the drive power you will now see the output power become
rather saturated, from these adjustments.
(Maximum ALC voltage produced is -10V when the amplifier output power is
over 200W.)
REAR PANEL ALC POT.
S
SS
ST
TT
TB
BB
BY
YY
YA
AA
AL
LL
LC
CC
C
A
AA
AL
LL
LC
CC
C
A
AA
AD
DD
DJ
JJ
J
A
AA
AC
CC
C
MAX MIN
T
TT
To
oo
o T
TT
Tr
rr
ra
aa
an
nn
ns
ss
sc
cc
ce
ee
ei
ii
iv
vv
ve
ee
er
rr
r
13
9. Protection Circuits
There are five major protection functions in this amplifier. If the amplifier has shut down
for some reason, before re-setting, correct the possible cause of the shut down. Turn off
the POWER once and back on to reset.
9-1 O. DRIVE (Over Drive / Band Miss-set)
When the drive power exceeds the 100W level, the amplifier will shut down to
STAND-BY mode (or receive) in order to protect the input side of the power FET’s.
This protection might also activate if the band is set wrong. This usually occurs,
when the amplifier band setting is lower than that of the transceiver.
9-2 O. HEAT (Over Heat)
When the temperature of the aluminum heat sink in the power amplifier reaches
80 degrees C, the amplifier defaults to RECEIVE mode to protect the power FET’s.
9-3 O. VOLT (Over Voltage)
If there is a sudden AC line voltage spike, the FET drain voltage may rise above
acceptable levels, and O. VOLT protection may trip.
9-4 FUSE (Fuse Blown)
If either of the glass fuses (15A) on PC1662V fails, “FUSE” lamp lights. Under
normal usage of the amplifier, this failure should rarely (if ever) occur. If it occurs,
there is a possibility that the power FET’s have failed together. If the amplifier
cannot be reset, consult with the dealer or the service center.
9-5 PR (Reflected Power Protection)
If reflected power from the antenna reaches approximately 80W, the PR protection
may trip. If it does, one solution is to reduce the drive power from the transceiver.
Or you may need to check that your antenna match (SWR) is still OK. If the match
cannot be corrected and the antenna system isn’t faulty, use an antenna tuner.
As noted above, the amplifier is equipped with several kinds of fast acting protection
circuits using the latest in analog technology. However, if the amplifier is operated in
such a manner that multiple protections work repeatedly over a long period of time, the
amplifier can be seriously damaged.
14
10. Explanation of Major Circuits
Four major circuit blocks are explained in their basic form and using signal flows.
10-1 Main DC Power Supply
10-2 Power Amp/ L.P.F.
10-3 RF Power Detector/ TX-RX Switching
10-4 Control Board
10-1 Main DC Power Supply
The main DC power supply feeds the 42V DC power to the final PA stage. It is a
state of art, switching power supply with high efficiency. A part of 42V line is
converted to 24V using a DC-DC converter and is supplied to the cooling fan.
10-2 Power Amp (PA PC1662V) / L.P.F. (PC1817)
The RF PA is the heart of this amplifier and is composed of four VRF150 MOS
FET’s made by Microsemi of USA. The amplifier is a parallel push-pull, class AB
amplifier. The gate bias supply circuit is regulated for the best stability and is
thermally compensated.
The PA has a 6dB attenuator on the input for gain reduction and to enhance the
stability of the wide band power PA. The heat sink has two different thermal
sensors to detect temperatures of 50 deg.C, and 80 deg.C, respectively. At 50 deg.C,
the cooling fan shifts into high-speed mode. At 80 deg.C, the amplifier will lock the
amplifier into RECEIVE mode to protect the power FET’s.
In the L.P.F. (output low pass filter) circuit, there are seven band filters that are
selected by the manual band switch. Each L.P.F. is used to reject harmonics so that
the amplifier meets international telecommunication equipment standards,
including FCC rule.
10-3 RF Power Detector / TX-RX Switch (PC1821)
As illustrated in the block diagram, there are two RF power detectors on this
board. One detects the drive signal level from the radio and the other monitors the
outgoing power and the reflected power from the load (antenna).
The TX-RX switch (Send-Receive switching) will switch the flow of drive
power/output power and the incoming signal from the antenna with two
high-speed relays mounted at the input and output sides of the PA.
15
10-4 Control Board (PC1818)
This is the heart of the control signal processing for the HL-550FX. It judges the
operating condition of the amplifier, as well as issuing the commands to the
peripheral circuits. Various analog signals are processed such as RF drive from the
transceiver, RF power signals at various points, DC power supply information, etc.
There are ope-amps, various three terminal voltage regulators, GAL logic device
etc. Warning signals are processed by the logic IC for Over Heat, Over Voltage, Pr,
Band Miss-set etc. Ope-amps produce the necessary DC signals to drive the Pf, Pr
meters. Also there is a control circuit that issues the drive shut down command in
case of the over drive, band miss-set and high antenna SWR conditions.
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11. Trouble Shooting
Failure Possible Cause Solution
AC mains not
operating
① AC fuses blown
② AC cord not plugged in
③ Interlock switch lifting
④ Wrong tap used on
power transformer
primary
① Replace with new ones.
② Plug in securely.
③ Screw bolts tightly on the top cover.
④ Correct primary wiring.
Can’t enter
Transmit
mode
① Remote control cable
not connected
② Protection circuits ON
① Check the cable and connect properly.
② Check the drive power, antenna SWR.
Reset with AC POWER switch.
O.Drive lights
① RF overdrive
② Band miss-set
① Decrease drive.
② Match the BAND correctly.
PR lights ① Reflected power high,
Antenna SWR high
② Poor connection to coax
cables
① Check/adjust antenna
(Or decrease drive.).
② Check the coax cable connectors.
O. Volt lights ① Drain voltage of power
amp extremely high
① Check AC line stability.
FUSE lights ② Fuse blown
③ Antenna SWR high
④ Short circuit
② Replace F202 and F203 (15A) on the
PA board (PC1662V).
③ Adjust the antenna.
④ Contact the distributor, or service
center.
O.Heat lights ① Internal Temperature
above 80 deg.C
Cool off until LED turns off. Check for air
intake blockages. Also check air vent on
top cover.
TVI, FMI ① Overdrive
② RF leakage from coax
cable, grounding wire,
AC power cord etc.
① Decrease the drive. Check ALC
setting.
② Insert common mode filters on
antenna cable or AC line. Add
clamp-on ferrite cores (TDK, Amidon,
Palomar) on various cables.
17
12. Parts Layout
12-1 Top View (Detailed)
12-2 Top View & Side View
12-3 PA Unit (PC1662V)
12-4 LPF Unit (PC1817), Sub AC Unit (PC1819)
12-5 Frequency Detector Unit (PCS1733), RF Power Detector Unit (PC1821)
12-6 Control Unit (PC1818)
13. Schematic Diagrams
13-1 PC1662V PA (Power Amplifier) Unit
13-2 PC1821 RF Power Detector Unit
13-3 PC1817 LPF (Low Pass Filter) Unit
13-4 PCS1733 Frequency Detector Unit
13-5 PC1818 Control Unit
13-6 Overall Block Diagram