While
tuning 8l I tube
type amplifiers
always
limit
the transmitting
time to no more
than
5
seconds with
a
l0
second
cool down.
It
is best
to use CW,
FM,
RTTY Mode
or a
Tuning
Pulser when
tuning an amplifier. This
will make it
easier to see
the
peak
of the
meters
while
adjusting the
plate
and
load
controls. A wattmeter
should
be used to
properly
tune
an amplifier.
Preset
the
plate,
load
and band-switch knob
according to the manual.
Then
set the
transceiver's
power
to
a desired drive level. It is
always best to
start at
low
drive.
(about
20
watts).
While transmitting
adjust
the
plate
control for
peak
output
power
by
watching
the
power
meter.
(Limit
5
seconds)
Then
adjust the load
control
for
peak
output
power.
(Never
exceed 5
seconds
of transmission time). tf
the amplifier is
producing
the
desired amount
of output
power
then
re-peak
the
plate
control to make
sure
it is
still at its
peak
for
output
power.
Make
sure the
plate
and
grid
current meters
never
go
beyond
the maximum rated
values.
If more
power
is
desired from
the amplifier and
the
grid
and
plate
currents
are below
the
maximum values,
increase
the transceiver's
power
until the
grid
meter
reaches
the
maximum
level for
the tubes. Then retune
the
plate
and
load
control for
peak
output
power.
Do not
transmit for more
the
5
seconds.
(When
the output
power
is increase
it will
cause the tubes
to
heat
up
faster
than
at
low
power.)
On
the final
tune make
sure the
load
control is
on the clockwise direction
of the
peak.
It is
always
good
to
reduce
the transceiver's
power
about
5
watts after tuning.
Then
switch transceiver
to SSB mode.
Never
increase
the
transceiver's
power
after
tuning the
amplifier. The
power
that was
being
produce
in the tune mode is
still the
same
for
SSB
just
the
meters
on
the
amplifier are not fast
enough to respond
to
voice
peaks.
The
output is
usually about 20
%
higher
because
the
high voltage is
closer to
no
load
voltage
Depending
on the voice,
and the amount
of speech compression,
the
meters
on
the amplifier
will read
only about l/3
to
Yz
of the real current. This is
also
true with
wattmeters.
Wattmeters
usually read
only about 50
% of
the PEP
power
when
operating
on SSB
Bird
Model 43
type meters may
only read
about
l0%
of the
output
power.
Some
wattmeters
are
label peak
and average
but only
read
average
peak
when
in
the
peak
position.
Wattmeters
that read
true
power
usually have
to
have
a
power
source
of some
kind to make
the meter work
and should
be
label
as True PEP
or
Active readins.
When
tuning
and operating the
amplifier make
sure the VSWR does not
go
high
on the
antenna No
more
than
2.1
for
fulI
power
or
3.1
for half
power.
The transceiver's
internal
tuner
cannot
be
used when
using
an amplifier. An external tuner
will
have
to be
used
between the
antenna and the amplifier
when the
antenna's
VSWR is
too high.
IMPORTANT ADDITIONAL INFORMATION
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