User Manual Model HL-500V
User Manual
Solid-State 144MHz Band
500W Linear Power Amplifier
Model HL-500V
 HL-500V is a solid-state VHF/144MHz band linear power amplifier with the
maximum output power of 500W.
Switching type AC to DC power supply is
built in. It is great for 2m DX communications as well as EME QSO.
 AC voltage is automatically selected between AC 100V and 240V. No rewiring
of AC primary voltage is required, if you change operating AC line voltage.
Only the AC plug change is needed to fit your particular operating location.
 A pair of the latest RF MOS FET , MRF151G’
s , designed by Motorola, are used
at the power amp stage to achieve a stable output of 500W max. Broad band
design has eliminated the troublesome tuning operation as is needed with a tube
type linear amplifier. Turn the AC power switch and you will be on the air. With
the duct structure for cooling air flow, an ideal cooling effect has been achieved.
 RF key circuitry is built in. When the RF driving power is detected, the amp will
be automatically keyed. Also the STBY ( stand-by ) terminal is located at the
rear panel with which the amp is keyed through the radio.
 Various protection circuits have been built in such as power supply, antenna, RF
power amp board etc. for the safety.
 A large analog meter monitors the forward and reflected power always.
 There are high voltages running inside the cabinet, such as AC100V, 200V,
DC50V etc. High RF voltage is also generated during the transmission. Do not
open the top cover carelessly.
 Rugged antenna with god SWR ( 1.5 or less )must be used to withstand 500W
continuous power.
 Do not exceed driving power of 20W ( and/or 50W, if selected so ).
( 144 ∼148 MHz Amateur Band )
VHF 2m Band
RF Drive Power
20W and/or 50W ( Switch selectable )
RF Output Power
In/Out Impedance (Zin/out)
50 ohms
Final RF Power Transistor
MRF151G x 2 ( by Motorola, M/A COM. )
Amp. Circuitry
Accessory Circuits
: ① Meterings for Pf & Pr
CW ,
( unbalanced )
Parallel Push-pull
② RF key circuit ( Carrier operated send/receive
switch )
③ Protection circuits for antenna open/short,
current/Idc, PA unbalance, over drive, over heat )
AC Power
AC 100V ~ 240V ( Auto select ) ,
In / Out connectors
345 x 145 x 390 mm ( WxHxD )
Approx. 12 kgs. ( 26.5 lbs.)
Accessory Parts
Coax Jumper Cable ( 69 cm ) x 1
RCA plug
Spare fuses
25A x 1 ,
2A x 1
AC power cord
Cooling Method
Forced Air with Book Fan
1.2kVA max.
4. Front and Rear Panels
This is a power switch to turn on and off AC main power. At off
position, the signals to and from the antenna will bypass the linear
② OPER. /STBY : At OPER. Position, T/R switching circuit is turned on and the amplifier
will become ready to work.
At STBY, the amplifier will be on stand-by mode, and amplifier will
be at through state.
③ METER Pf / Pr : As this switch is pushed, meter scales of “
Output power”(Pf) and
Power”(Pr) are changed.
④ DRIVE 50W/20W : This switch will select the driving power from the transceiver i.e.
50W or 20W.Pushing the switch, LED lamp of either 50W or 20W
will light reciprocally.
SSB / FM : This switch changes the time lag from TX to RX , when using RF
key circuit. At FM, TX to RX switching is made instantly. At SSB,
time lag will be approx. one second. For CW operation using RF
key, set this switch at SSB.
⑥ LED Lamps
Pf / Pr
Lamps will light as the METER switch ③ is pushed to either Pf or
Drive Power : Lamp of corresponding power level of either 50W or 20W will light.
PROT ( Protection ) : There are protection circuits for “
Over drive “
power from antenna “
Over heat ( inside of amp. ) ”
PA over
current “
, and “Unbalance of PA units “
. When either one of these
works, PROT LED will light indicating that protection circuit has
shut down the amplifier. Turn off the POWER switch and turn on
again to reset the protection. LED will go off.
SSB / FM Mode : Lamp will light as either FM or SSB is selected.
LED will light when the amplifier is transmitting.
Lamp will light when OPER/STBY switch ② is turned on.
Meter will read each power of to and from the antenna , Pf and Pr.
Rear Panel
N connector. Connect the cable from the antenna. The antenna
must have a
power handling capability of 500W ( continuous ) minimum.
⑨ TX
RF input N connector. Connect to the radio with the supplied coax
jumper cable.
⑩ FUSE 25A
25A fuse holder for final amp unit. ( This is not a fuse for AC power
line. )
Ground terminal.
2A fuse holder for power supply of control circuit.
The terminal to be grounded through ACC and/or REMOTE
terminal ( or called “
SEND”, “TX GND “depending on the
radio manufacturer ) of the radio to key this linear amp. NOTE :
BOARD ( See following page. ) For RF keying, do not remove
this plug. Connecting STBY terminal to the radio, TX/RX
switching will be very smooth for ssb and cw modes.
ALC jack. Connect to external ALC input pin of the radio. See the
radio manual. With this connection, output power will be
maintained at certain level even if the amp is over driven by the
( Note : ALC connection is not necessarily required for
modern well controlled radio. )
Connect the supplied AC cord here. The internal AC to DC power
supply will automatically select 110/115/120V and 220/230/240V.
You will not have to change or select any of AC primary voltage.
Potentiometer to adjust ALC output level of negative DC voltage.
When the ALC cable is connected to the radio ( see ⑭ above ),
turn this potentio- meter counter clock wise, and output power of
the linear amp will start to decrease. ( See the manual of the radio
for the proper external ALC voltage level. Variable DC voltage of
0 to negative 9V is available at this jack for 500W is produced. )
5. Connection
① Referring to the illustration at page 8, confirm if all the connections are made correctly.
Turn on the power of the transceiver. Keep the power switch of this linear amp at OFF
position. Also set OPER./STBY switch at STBY position.
On reception, signals from the antenna pass through the linear amp and received signals
will be heard from the radio.
② Check the SWR of your antenna system choosing the frequency channel not occupied with
other stations. SWR must be made relatively low , 1.5 or lower if it is too high.
③ Turn on the power switch of the linear amp.
④ Push the drive power level switch to select the proper level of either 20W or 50W in
accordance with your radio.
⑤ Push the MODE switch to select either SSB or FM. When the STBY terminal is connected
to Remote or ACC terminal pin of the radio, please select “
FM”rather than SSB. And TX to
RX switching will be made with no time lag that will make smoother SSB communication.
⑥ Turn the OPER./STBY switch to OPER. position. If you key the transceiver, this amplifier
will also be keyed with either rf key or hard key of the radio. Amplified high power signal
will be emitted form thee antenna. Power meter will be deflected according to the
transmitting power ( Pr ), and will indicate the reflected power as well ( Pr ) if the meter
switch is turned to Pr. Pr ( reflected power ) may increase depending on the power handling
capacity of the antenna.
⑦ If you are going to run the radio without a linear amplifier ( on barefoot ), please turn the
power switch off , leaving all the cables connected as they are. ( Or you may simply turn the
OPER./STBY switch to STBY position, and signals to and from the radio will bypass the
linear amplifier. )
6. About The Protection
This linear amplifier has four protection functions as follows. If the limit of the certain
parameters are exceeded, protection circuit will shut the amplifier for the safety and PROT
LED will light..
6-1. Temperature
When the internal temperature of the cabinet reaches 40 deg. C, the cooling fan starts to
work. Furthermore “
PROT”LED lamp lights when it reaches 90 deg C.
( Solution : Wait for a while at stand by mode until PROT lamp goes off. )
6-2. Over Drive Protection
If the driving power from the radio exceeds the rated input power of either 20W or 50W
( or approximately 120% of rating ), “
PROT”LED will light.
( Solution : Check the output of your radio.
Even if the high power radio is adjusted for
lower output of 20W, it may emit high output momentarily, when keyed. This causes the
over drive.)
6-3. Reflected Power Protection ( Pr )
When the reflected power from the antenna reaches 50W, “
PROT”LED will light.
( Solution : Check the antenna for SWR and maximum power rating as well. )
6-4. Over Current Protection
When the total DC current flowing into the MRF151G’
s , MOS power FET, exceeds the
rating of 22A, “
PROT”LED will light. If the antenna SWR is relatively high, total drain
current of power amp will vary according to the condition.
( Solution : Check the antenna SWR. )
** When the “
PROT”has worked, turn off the POWER switch once to correct the possible
If the POWER switch is turned on again, PROT will be reset and LED lamp will go off.
When the “
STBY ⑬”is going to be connected to the radio, jumper plug J14 must be pulled
off the control pc board as shown in the following illustration. Be sure to pull the AC Main
power plug off the wall and remove the top cover of the amp to locate J14.
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