Eddystone 990R - Mechanical Construction; General; Internal Layout

M
ECHANICAL
CONSTRUCTION
General
.
The
990R Receiver
in
its
standard
form
is
suitable
for
bench-mounting
only.
Rubber
feet
are
fitted
to
raise
the
controls
into
a
convenient
operating
position.
Receivers
are
available
for
rack-mounting
and
are
designated
Model
99OR/RM.
Dimensions
and
fixing
are
arranged
to
suit
standard
19-inch
Post
Office
racking.
Conversion
kits
can
be
supplied
to
allow
conversion
of
standard
receivers
already
in
service.
A shock-
absorbent
mounting
is
available
if
required.
Dimensions.
19s-
lb.
(8.8
kg.)
20 lb.
(9
kg.)
Internal
Layout
.
Printed
wiring
techniques
are
employed
throughout
with
the
exception
of
the
Power
Supply
Unit
which
is
built
on
a
small
metal
sub—
chassis
located
at
the rear
of
the
set
adjacent
to
the
IP
Pre-amp./
Filter
Unit
in
the
rear
right-hand
corner.
The
various
printed
boards
employed
are
as
follows
s
-
1.
RP
TUNER
UNIT
(TRI-TR4)
.
One
main
board
plus
four
small
boards
carrying
the
coils
and
trimmers
for
the
various
stages.
2.
CRYSTAL
OSCILLATOR
UNIT
(
TR5-TR7
) .
One main
board
plus
one
small
board
carrying
the
coils
and
trimmers
in
the
Crystal
Oscillator
Stage.
The
crystal
holders
are
mounted
on
the
main
board
and
are
accessible
after
removing
the
rear
cover.
3.
CRYSTAL
CALIBRATOR
UNIT
(TR8
&
TR9)
•
Mounted
on
top
of
RP Tuner
Unit.
4.
IF
PRE-AMP
.
/FILTER
UNIT
(TR10-TR14)
.
Access
is
through
a
removable
cover in
the
right-hand
side-plate
.
8.
MAIN
IP
BOARD
(TR15-TR29).
The
two
Emitter
Follower
Units
(TR13 &
TR18A)
and
the
CW
Detector/BFO
Unit
(TR23-TR25)
are
in
separate
screened
assemblies
and
are
mounted
directly
onto
the
main
board.
6.
VIDEO
AMPLIFIER
(TR30
&
TR3l).
7.
LOW-LEVEL
AUDIO
AMPLIFIER (TRJ2
&
TR33).
8.
HIGH-LEVEL
AUDIO
AMPLIFIER
(TR34-TH38).
-
12
-
7
Separate
boards
located
at
rear
j of
receiver
.
Weight
*
Bench-mounting
version
Rack-mounting
version