DRAKE MN2700 Instruction Manual - Page 11
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Print PageCHAPTER Ill
OPERATION
3-1.
FRONT
PANEL
CONTROLS.
(Figure
1-1)
VSWR
SET
Control:
Varies
the
sensitivity
of
the
VSWR
sensing
circuitry.
Meter:
Displays
either
forward
power
in
watts
or
VSWR
as
selcted
by
meter
switches.
VSWR
SET
Switch:
Used
to
calibrate
the
meter
for
VSWR
measure
ments.
VSWR
READ
Switch:
Causes
meter
to
indicate
VSWR.
200
and
2000
Watt
Switches:
Causes
meter
to
indicate
forward
power,
either
200
or
2000
watts
full
scale.
ANTENNA
Switch:
Selects
the
desired
antenna
and
grounds
all
unused
antenna
terminals.
Positions
are
provid-
ed
for
Dummy
Load
(which
can
also
be
used
for
an
additional
antenna
or
as
a
grounding
posi-
tion
for
antennas
1
through
4),
2
coaxial-fed
antennas
(1,2)
and
two
long-wire
antennas
(3,4
without
accessory
balun).
With
accessory
B-1000
balun,
balanced
feedline
capability
or
1:l
and
41
match
to
long-wire
antennas
are
available.
BAND
Switch:
Selects
the
fixed
capacitors
and
inductors
for
each
band.
In
the
DIRECT
position,
bypasses
the
matching
network
and
connects
the
RF
through
the
meter
circuitry
directly
to
the
antenna
selected.
REACTIVE
Tuning:
Tunes
out
the
series
reactive
component
of
the
antenna
impedance.
Reactive Range
Switch:
Switches
in
additional
fixed
capacity to
provide
additional reactive
tuning
range.
RESISTIVE
Tuning:
Varies
the
resistive
component
of
the
MN-2700
output
impedance
to
match
the
series
resistive
component
of
the
load.
Resistive
Range
Switch:
Switches
in
additional
fixed
capacity
to
provide
additional
resistive
tuning
range.
3.2
REAR
PANEL
CONNECTIONS.
(Figure
3-2)
XMTR
Jack:
50-239
socket
for
input
from
the
transmitter
DL
Jack:
50-239
socket
for
the
connection
of
a
dummy
load
(or
another
coaxial
fed
antenna).
ANT
1-and
ANT
2:
50-239
sockets
for
2
separate
coaxial
fed
antennas.
LW3
and
LW4:
Screw
terminals
for
two
longwire
antennas,
when
used
without
the
accessory
balun
(1:l
im-
pedance
ratio
to
matching
range
of
network).
Numbers
correspond
to
ANTENNA
selector
switch
position.
3.3.
USE
OF
THE
DRAKE
B.1000
ACCESSORY
BALUN
Installation:
Remove
the
three
screws
at
terminals
marked
LW3,
LW4,
NC
and
then
reinstall
these
screws
through
the
holes
in
the
balun
board
to
the
matching
terminals
on
the
MN-2700.
Also,
in-
stall
the
two
mounting
screws
in
the
other
two
corners
of
the
balun
board
to
the
MN-2700.
Balanced
Feedlines:
The
two
wires
of
the
balanced
feeders
are
con-
nected
on
the
top
of
the
balun
board,
under
the
heads
of
terminal
screws
marked
BAL
and
BALlLW(1:l
or
4:l).
The
ANTENNA
selector
switch
is
placed
in
position
3
when
this
antenna
system
is
used.
Long-Wire
Antenna
Using
Balun:
(Cannot
be
used
when
balanced
feeders
are
at-
tached.)
Connect
the
longwire
to
the
terminal
marked
BALILW
(1:1
or
41).
In
ANTENNA
switch
position
3,
the
antenna
will
be
matched
with
a
1:l
impedance
ratio.
In
position
4,
the
antenna
will
be
matched
with
a
4:l
impedance
ratio,
providing
for
a
higher
impedance
range
matching
capability.
It
is
absolutely
necessary
to
have
a
good
RF
ground.