1 kW TTS1000B TRANSMITTER IPA ASSEMBLY
PUB96-30 rev 1: Jul 1, 2010
30-7
1 kW IPA Assembly VHF
2.Turn
both
bias
potentiometers
to
their
maximum
resistance
for
minimum
bias.
Short
C6
with
a
clip
lead.
This
zero
‐
biases
the
"B"
half
so
it
does
not
interfere
(via
L9)
with
the
"A"
half
being
adjusted.
3.Apply
the
supply
to
the
B+
terminals
and
adjust
R1
bias
‐
adjust
potentiometer
for
600
mA
drain
current
on
side
"A".
Turn
off
the
supply,
change
the
clip
lead
to
short
C2
instead
of
C6,
turn
on
the
supply
again,
and
adjust
R7
bias
‐
adjust
potentiometer
for
600
mA
drain
current
on
side
"B".
These
will
be
the
starting
points;
the
bias
current
settings
and
L9
will
be
readjusted
during
system
test,
for
minimum
intermods
and
FM
noise.
Disconnect
the
clip
lead
after
adjusting
bias
currents.
4.Connect
a
30
dB
20
W
attenuator
to
the
output
of
the
amplifier.
5.Apply
B+
to
both
supply
connections
of
the
amplifier.
6.Apply
a
low
level
sweep
to
the
module
and
measure
the
DC
input
current
(about
1.2
amps)
and
gain.
Amplifier
gain
by
itself
should
be
15
to
17
dB,
and
with
preamp
included
and
R5
at
maximum,
overall
gain
should
be
between
33
and
37
dB.
Sweep
response
should
be
flat
within
1
dB
over
the
band
as
shown
in
the
sweep
diagram
from
page
4,
repeated
below.
Note
that
the
sweep
curves
are
applicable
to
the
push
‐
pull
FET
amplifier
only
and
the
preamp
is
not
included.
