FAX 5/10/20/30/40KW
October 28, 2013
4
‐
3
888
‐
2720
‐
001
WARNING:
Disconnect
primary
power
prior
to
servicing.
Copyright
©2013,
Harris
Broadcast
Figure 4-2 FAX10/20/30/40 Drive Chain
The
block
diagram
in
Figure
4
‐
2
shows
the
FAX10/20/30/40
RF
flow
from
the
exciters
to
the
output
of
the
IPA
switch
that
drives
the
power
block
splitter.
The
dual
exciters
are
shown
feeding
an
exciter
selector
switch.
The
exciter
selector
switch
relay
is
located
on
the
System
Interface
Control
Module
located
to
the
right
of
the
Power
Supply
Modules.
In
a
dual
Exciter
system,
the
system
controller
will
automatically
switch
when
the
on
‐
air
exciters
RF
power
drops
below
a
preset
level.
This
level
can
be
set
by
the
user.
The
output
of
the
Exciter
switch
relay
goes
to
the
IPA
Switch
Board
input.
The
input
of
the
RF
Switch
board
has
a
3
dB
pad
for
isolation
between
the
exciter
and
the
IPA.
The
IPA
switch
has
2
relays
one
on
the
input
to
the
IPA
and
one
on
the
output
of
the
IPA,
these
switch
in
tandem.
For
protection,
the
transmitter
will
be
muted
while
switching
occurs.
The
RF
Switch
board
also
contains
the
IPA
RF
output
level
detector.
The
IPA
switches
when
the
detector
output
drops
below
0.5
VDC.
4.1.2
FAX5 RF Block Diagram
The
FAX5
utilizes
the
same
chassis
and
hardware
as
the
FAX10.
However,
it
uses
fewer
PA
modules
and
Power
supplies
and
also
has
a
slightly
different
RF
Chain.
In
the
10
kW
transmitter
there
are
14
FET’s
to
achieve
10
kW,
so
in
a
FAX5
seven
FET’s
are
required.
In
this
case
there
are
3
PA
modules
and
one
IPA/PA
module.
Refer
to
Figure
4
‐
3,
the
exciters
now
have
two
different
paths
and
only
1
IPA.
The
other
FET
in
the
IPA
slot
runs
continuously
as
a
PA.
Exciter
A
is
a
high
power
exciter
and
bypasses
the
IPA
and
drives
the
7
‐
way
splitter
directly.
This
requires
the
exciter
to
output
approximately
60
Watts
which
is
the
normal
IPA
power.
If
Exciter
A
power
out
drops
below
the
preset
level
(0.5
VDC
on
the
detector)
and
the
transmitter
switches,
Exciter
B
then
drives
the
IPA
and
runs
at
approximately
3
Watts.
The
RF
Switch
that
was
used
for
IPA’s
now
is
the
exciter
switcher
in
the
FAX5.
The
Exciter
switch
that
resides
on
the
System
Interface
board
is
not
used.
All
other
circuits
in
the
FAX5
work
identical
to
the
FAX10.
Exc A
Exc B
Rear
Panel
J4
J5
IPA
Module
RF Switch Bd
System Interface
Board
J12
J13
J4
J3
J2
J7
IPA RF Level
To Sys Inf
To 14-Way
Splitter
PA BackPlane
RF Switch Bd
RF Switch Bd relays switch in
tandem. For FAX20/30/40 All IPA’s
will be on A or B
3 dB Pad provides isolation between
Exciters and IPA and helps prevent
overload of IPA
IPA RF Level Detected on
RF Switch board, it is DC
voltage used for IPA RF
Fault and switching
A
B
Exciter power displayed
on FAX is a DC Voltage
from Exciter. There is
no RF detector for
Exciter Power
J4
J5
J6
Summary of Contents for Flexiva FAX 5KW
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