Cubic SWAN SS-15 User Manual

RCVR
MIX
-
The
receiver
mixer
arnplifier
also
uses
a
dual
gate
MOSFET
translrt"i-qibO.
ift"
outputs
from
the
RF amplifier
and
the
VFO
are
mixed
do
convert
the
received
RF
signal
to
the
IF
frequency
of
i,S
UHr.
ffre
VfO
signal
is
switched
and
controlled
by
the
VFo
SELECTOR
switch.
NOISE
BLANKER
-
A
portion
of
the
receiver
mixer-output
is
connected
to
the
noise
blanker
circuiis.
th"t"
circuits
detect
noise
pulses
and
amplify
and
shape
a Ufanfcing,Pgll-e-:-
This
blanking
pulse
is
used
by
the
FILTER
bRfVrn
Aflo
n6fbE
SWITCH
(described
in
the
fol-
lowing
paragraph)
to
atteTuate
the
unwanted
-noise
ahead
of
the
IF
amplifier.
Tha
lircuits
i".i"a"a
in
the
noise
blanker
are
a
dual
gate
MgSFET
IF
anplifier
q+Oi,
"
FqT
pulse
detector
Q405
and
a
bipolar
transistor
puls"_:ttlgi:-"r,d
rirl:e
driver
Q406.
The
level
established
b;";[;
'nilllrrn
lbvrl
control
a1lows
the
noise
blanker
to
detect
3ust
the
unwanted
noise
signals
received.
FILTER
DRIVER
AND
N0ISE
SWITCH
-
The
blanking-pulse
'
as
described
above,
'cause;
;;
t"i"rr."a
series
connectea
Fgt
transibtors Q402
and
Q405
to
:t;p-
conductilg..
-
. Fi;::
tl:-t"
two
transistor
circuits
are
connected
iir'series
wiEtr
the
IF
signar,
t 50.db
attenuation
of
the
IF signal
ii
ir"ut"a
"".tt
tine
the-FET
transistors
stop
con-
ducting.
The
blanking-pulse
and
the
subsequent
switching
of
the
FET
transistors
is
as
fast
as
the
unwanted'noise
pulse'
The
end
result
is
complete
attenuatio"
or
itt!
a
single
noise
pulse
or
a
series
of
.roi!"-prrf
r"r.
fft"-*""i"a
signals
6etween
the
noise
pulses
ISSB
or
CiV)_are
p"tt*a
on
to
th;
IF
amplifiers
without
attenuation.
rf
the
noise-is
ihort
duration
pulses.with
low
per-
centage,,on
timerr,
then
ttt"-d"iirea
signals
appear
to
the
ear
to
be
unaffected-
XTAL
FILTER
which
is
wide
narrow
enough
Thecrystalfilternarrowsthe-IF.passbandtoz.TKHz
enough
to
affli-t"pioauction
of
tha,
hunan
voice
and
i"'riit"i
adj
acent^
frequency
interference
'
IFAMP-TwodualgateMOSFETtransistorsareuse{.tomakeupthe
receiver
IF
amplifiercyrt"*.
The
first
IF
arynlifier
Q407
is
AGC
controlled
and
a
portio'
oi"'itt
o"tq"!
is
used^
to
'
rate
the
rrsrl
merer.
The second
IF
anplifi.t
qtOb
is
not
AGC
co
'olled
but
a
portion
of iti-ouiput
is'"i"J
to'develop
the
AGC
v'ltage
'
It
should
be
nored
here
that;h;
ii."t
IF
inplifieT.lt
tl:'_lt?l
1n
the
transmitt;;
and
a
description
of
its
transmitter
usage
ls
found
later
in
this
section'
-22-

Cubic SWAN SS-15 Specifications

General

Brand	Cubic
Model	SWAN SS-15
Category	Transceiver
Language	English