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Heathkit SB-401 - HETERODYNE OSCILLATOR

Heathkit SB-401
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Gegrnsrexit
EQUIPMENT
REQUIRED
The
following
test
equipment
is
required
for
alignment
of
the
Transmitter,
1,
A
50
Q
nonreactive
dummy
load
(such
as
Heathkit
Model
HN-31
Cantenna),
2,
An11
megohm
input
VTVM
(such
as
Heath-
kit
Model
IM-11),
3,
An
RF
probe
for
the
VTVM
(such
as
Heath-
kit
Model
309-C),
4,
A
Ham
band
or
good
general
coverage
receiver
with
calibrated
S
meter
(such
as
Heathkit
Model
SB-303).
5,
A
CW
key
plugged
into
the
KEY
jack,
CAUTION:
Do
not
depress
the
key
until
specifically
instructed
to
do
so,
|
Refer
to
Figure
2-2
(fold-out
from
Page
93)
;
for
test
point
and
adjustment
locations,
“8.6
MEGAHERTZ
TRAP
(_)
Preset
the
variable
capacitor
on
terminal
board
#1
as
it
is
shown
in/Figure
2-2,
if
it
was
not
aligned
previously
using
the
SB}303
Receiver.
'
21
MEGAHERTZ
TRAP
The
21
MHz
trap
(RFC1)
was
presct
at
the
factory.
Do
not
change
the
setting
of
this
trap.
HETERODYNE
OSCILLATOR
(_
)
Sci the
transmitter
panel
controls
as
follows:
FINAL
(Knob)
80
(Lever)
50
9,
LEVEL
counterclockwise
FREQ.
CONTROL
UNLOCKED
METER
REL.
PWR.
FUNCTION
OFF
BAND
3.5
MODE
CW
_
—
Plug
the
line
cord
into
a
120
V
AC
wall
outlet,
Turn
the
FUNCTION
switch
to
STBY,
Nee
a
Connect
the
DC
probe
of
the
VTVM
to
the
oscillator
test
jack.
Page
97
( )
Adjust
the
slug
of
the
3.5
HET
OSC
coil
for
a
maximum
indication
on
the
VTVM
(negative
DC),
CAUTION:
Be
sure
the
alignment
tool
is
fully
seated
in
the
coil
before
attempting
to
turn
the
coil
slug,
It
may
be
necessary
to
turn
the
coil
slug
several
turns
counterclockwise
to
start
the
oscillator,
(_
)
Turn
the
slug
1/4
turn
counterclockwise
to
insure
positive
starting
of
the
oscillator.
(_)
Turn
the
BAND
switch
from
3.5
to
7.0
and
back
to
3.5
to
see
that
the
oscillator
starts
oscillating.
If
it
does
not,
turn
the
slug
slightly
until
positive
operation
of
the
oscillator
is
obtained.
(Readings
of
approximately
—3
volts
or
higher
are
normal.
They
will
vary
from
band
to
band.)
NOTE:
When
adjusting
this
coil
in
one
direction,
the
oscillator
output
voltage
will
change
rapidly;
when
adjusting
the
coil
in
the
opposite
direction
from
the
peak,
the
output
voltage
will
change
slowly.
Adjust
the
coil
in
the
direction
that
gives
the
slower
change
in
output
voltage.
(
Place
the
BAND
switch
in
the
7,0
position,
(
—
ee
Adjust
the
slug
of
the
7.0
HET
OSC
coil
for
a
maximum
indication
on
the
VTVM,
(
)
Turn
the
slug
1/4
turn
counterclockwise
to
insure
positive
starting
of
the
oscillator,
Turn
the
BAND
switch
from
17,0
to
3,5
and
back
to
7,0
to
check
for
positive
oscillator
operation
on
the
7,0
band,
(
~
~
Repeat
the
same
procedure
for the
14,0,
21,0,
28.0, 28.5,
29,0,
and
29.5
positions
of
the
BAND
switch,
and
adjust
the
cor-
responding
HET
OSC
coil,
Check
each
band
for
proper
oscillator
operation
by
switch-
ing
to
a
different
band
and
back
again,
(
(_
)
Return
the
BAND
switch
to
the
3,5
position,
(
~
Disconnect
the
DC
probe
of
the
VTVMfrom
the
oscillator
test
jack,
CARRIER
GENERATOR
Set
the
FUNCTION
switch
to
TRAN,
Rotate
the
LEVEL
control
fully
clockwise,
ad
(
(
(
—
~~
ww
Connect
the
VTVM
RF
probe
to
the
E
pin
on
the
top
of
the
carrier
generator
cir-
cuit
board,
Depress
the
key,
This
should
close
both
relays,
(
~~

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