q
it
rl
t1
l!
Unwanted Sideband
Suppression:. .
.
.
In excess
of
30 db.
Carrier Suppression:.
. . .
Power
Requirernents:. .
. .
In
excess
of
40 db.
350
VDC, 85
MA
(Average)
30
MA
(Standby)
140 MA
(Transmit)
6.3 VAC, 3.5 AMP
2
L/2",
200
ua movement,
indicates
carrier
null
and
relative
power
output.
10"
high
,
6 3/ 4,
'
wide,
13"
deep.
10
lbs.
14 Ibs.
C
ARRI
ER
Meter:.
. .
.
Cabinet:.
Net Weight:.
Shipping
Weight:.
Before
proceeding
with
the
circuit
description
of
the SB-
10, it
may
be desirable
to explain the
nature
of an
SSB
signal,
giveabrief
history, and
discuss
the advanteges
of SSB operation
plus
methods
of
generating
a SSB
signal.
INTRODUCTION
The
SB- 10 is designed
specilically
as
a matching accessory
unit
to the Heathkit
"Apache"
Model
TX-l Transmitter
to
provide
a capability for
SSB operation
on the 80, 40,20, L5,
and
10 meter
amateur
bands.
While
the SB-10 can be
plugged
directly into
the
"Apache",
with slight modifi-
cations it
can
be used
with the Heathkit
DX- 100 and
DX-
100E}
transmitters. The
primary
feature
of the
SB-10
is that
it allows utilization of all
RF circuitry in
the companion transmitter, thus
making
use oI
the operator's investment in
AM
gear
and enabling him to retain his high level
AM
capability.
This feature
brings
the
cost
of an SSB capabitity within the budget of
all amateurs
and
will
afford them
the opportunity to experience
the advantages of SSB operation,
The
SB-10 obtains
power
fromthe companion
transmitter. It features
a built-in electronic voiee
control
with anti-trip
circuitry to
prevent
the
receiver audio output
from
keying
the transmitter
during Iistening
periods.
A
sensitive tuning
meter
is
provided
for
accurate carrier
null
and
indication
of relative
power
output.
Panel controls
include
the bandswitch, balanced modulator
and output
tuning,
two carrier
null controls, sideband selector
(upper,
lower, AM), function
switch
(VOX,
standby, manual), audio
gain,
and the
microphone
connector. Two
controls on the
rear
apron
provide
VOX
and anti-trip sensitivity adjustment. Relay contacts are
provided
for
receiver
muting, keying
the exciter stages of the transmitter, and operating an antenna
relay.
The
power
plug
plus
the input and
output connectors
are
also located on
the
rear apron.
E
Figure
1
The normal
10076
ampiitude rnodulated RF
car-
rier
presents
a
frequency
spectrum like that
shown
in
Figure
1.
For illustrative
purposes,
we will.
assume
that the
-"u"itla?
""*""*i
of a
single
tone. Speech
modulation,
of course, will
produce
side frequencies occupying
identical
bands on the upper and
lower sides
oI the
carrierl
thus the term
sidebands. The
carrier itself conveys no intelligencel
ail intelligence
is
contained in the sidebands. Furthermore, since
thelower andupper sidebands
are identical.
one sideband
can
also
be
e
liminated
leaving
only
that
part
of the signal necessary
to
convey intelligence,
a sing-te sideband. The carrier
can
be
re-inserted
at the
receiver
for demodulation purposes,
IfrffiTffii6iiig
the
picture.
What
is
gained
by this
process?
U'
t-
--.1
o
h
e.
Page
3
To Next Page
Loading...