Icom IC-725 Instruction Manual page 30

3
MAINTENANCE
AND ADJUSTMENT
8-7
ADJUSTMENTS
Your
IC-725 has been thoroughly adjusted
and checked
at
the factory before being shipped.
All adjustable
trimmers and
coils
should be adjusted by
an
authorized
Icom
Dealer or Service Center. Your
transceiver
warranty does not cover problems caused by unauthorized
internal adjustments.
(1)
MAIN
DIAL
BRAKE ADJUSTMENT
The
tension of the
MAIN
DIAL may
be adjusted to
suit
your
operating requirements.
•
ADJUSTMENT
POSITION
1
)
The
brake adjustment screw
is
located
on
the
left
side
of the
MAIN
DIAL.
2)
Turn
the brake adjustment screw clockwise
-or
coun-
terclockwise
to a
comfortable
tension
level
while
turning the
MAIN
DIAL
continuously and
evenly
in
one
direction.
(2)
PA UNIT
IDLING
CURRENT
The
PA
unit operates
with
a linear amplifier
and
requires
some
idling
current to flow through the
driver
and
final
transistors
to obtain bias voltage.
»PA UNIT
PA UNIT
•
DRIVER TRANSISTORS
IDLING
CURRENT
Ammeter
>
FINAL
TRANSISTORS
IDLING
CURRENT
Ammeter
1)
Preparation:
[POWER]
switch
->
OFF
[MIC]
control
-+
Max. counterclockwise
[RF PWR]
control-*
Max.
counterclockwise
Microphone
-»
Disconnect
Ammeter
100
m A
range for driver
transistors
500
mA
range for
final transistors
2)
Unsolder points indicated by
*1
and
*2.
3)
Properly
connect
test
leads to points.
See diagrams
for
the
driver
and
final
amp.
adjustments.
4)
Turn
transceiver
power ON.
5)
Push the [SSB] switch to
select
LSB
or
USB
mode.
6)
Push
the
[TRANSMIT]
switch IN to transmit.
7)
Adjust
R8
to
set
50
mA
for
the driver
amp.
Adjust
R19
to
set
300
mA
for
the
final
amp.
8)
Turn
transceiver
power OFF.
9)
Re-solder the de-soldered
points.
C28,
EP21