A fuse holder is mounted on the rear panel with a 3 amp 3AG
fuse provided. Do not use a larger capacity fuse or the amplifier
transformer
and power supply may be .damaged .due to simple
secondary component failure.
The AC line in the amplifier is bypassed and the lack of a ground
will result in a "shock hazard". Make sure the chassis is connected
to ground or other equipment.
The chassis should be connected to a good earth ground. Water
pipes and other house fixtures are not recommended.
Also, lack of a good ground can result in improper operation in
several respects, including TVI problems.
The
Linear
Amplifier
will
work
with
the common
antenna
systems designed for the 25-54 MHz* range, provided the antenna
has a resistive input impedance between 40 and 70 ohms. The
SWR should be kept to a minimum 2: 1 or less.
The output connector provided is an SO 239. For connection of
your antenna you will need a PL 259 plug.
ON-OFF Switch
Controls 120 VAC power to amplifier
Standby-Operate Switch
.....
Activates the automatic antenna
relay circuit
AM-FM
&
SSB-CW Switch
.. Adjusts time constant of automatic
antenna relay
Green Indicator Light
Visual indication of applied
120 V AC power
Red Indicator Light
Visual indication of RF energy output
Tune Controi
Adjusts resonant frequency of
output circuit.
Load Control·
Adjusts coupl ing of output circu it
to antenna
WARNING
WHEN THE AMPLIFIER IS USED IN THE BUSINESS BAND, AD-
JUSTMENTS MUST BE MADE ONLY BY A FCC LICENSED
TECHNICIAN.
The 480
Linear
Ampl ifier
is factory
adjusted for the range
25-32 MHz. Operation
over the range 32·40 MHz requires a
change in the number of turns in L 1 (RF Tank Coil). A shorting
tap is placed on the end of the coil, from the left·hand side as
viewed from the front panel (see fig. 2) to the first turn, counting
from the left side.
This Amplifier
must be used with
a transmitter
or transceiver
capable of at least one watt output.
Install
knobs supplied
in separate
parts pack.
Fully
mesh
both the Tune and Load Capacitors,
then install
the small
knob
on the
Tune and the big knob on the Load capacitor
shaft,
insuring
that the marking on the knobs are horizontal
and pointing
to the left when viewed
from the front.
Before applying any RF power to the linear, pretune the tune
control
to the desired frequency at which you wish to operate.
See illustration.
.~
~.
For example, if your desired operating frequency is 31 MHz then
set the tune knob at midpoint between 29 and 33 as shown.
For operation on the 50 to
54
MHz band set tune control to the
29 MHz position.
Then refer to 50 to
54
MHz Operation.
I
FIGURE I TUNE CONTROL KNCB
r?'"\
Fitst place the function
switch in the AM-FM position. Set
"L
tune control
in accordance with the warning
in "Operation"
section.
The load control
should
be positioned
so that
the
capacitor is fully
meshed.
Now push the ON·OFF Switch to ON, the green visual indicator
will light.
After
warm-up, push the Stby-Oper to OPER. This will energize
the automatic antenna relay control circuitry.
Apply
drive
power
by
keying
the
excfter
(transceiver)
microphone
and quiCkly adjust the tune control
for maximum
brilliance of the red visual output indicator.
Remove drive power
after adjustment.
Do not apply drive power for more than five seconds without
adjusting the tune control or damage to the tubes can result.
Reapply drive power and advance (clockwise)
the load con-
tro~' note the increase
in brilliance
of the red output
in-
dicator.
Adjust
the load control
for maximum bri lIiance
of
the output
indicator.
Now, go back to the tune control
and
reset for maximum output.
Remove drive
power.
Readjustment
of the tuning and loading controls several times
will produce maximum
output.
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