EDDYSTOHE
VHP
RECEIVER
MODEL
99QR
The EDDYSTOHE
Model
990R
is
a
fully
transistorised
single-conversion superhet
for
CW,
AM
and
Fid
reception
in
the
VHF band
27-240
MHz. It
is
suitable for use
over
the
temperature
range
0-50°C
and
can
be
supplied
with a
matching panoramic display
unit
when
visual
signal
analysis
is
an
additional
requirement.
Operating voltage
can
be
either 12V
DC
or
any
standard
AC supply.
Advanced
circuit
techniques
are employed
throughout,
performance
is
of
a high
order
and the
design
will
be
found
suited to
many
varied
applications
including
normal
comm-
unications
work,
interference
checking
and
noise
measurement.
Field use is facilitated
by
the
ability
to
operate
direct
from
low-voltage
supplies
with low
current drain.
The
complete
tuning
range
is
covered
in
four
switched bands
which
give
adequate
bandspread
even
at
the
higher
frequencies.
Local oscillator
arrangements permit
oper-
ation
with crystal
control
(up
to
eight
switched
channels),
external
frequency
control
or
normal
continuous
tuning.
Selectable
bandwidths
of
30
kHz and
200 kHz
are provided,
using
a
crystal
filter
in
the
narrow
position.
Alternative
crystal
filters
are
avail-
able
to
order
when
other
bandwidths
are
required.
Two separate
outputs
are
available
from
the
10.7
MHz
intermediate
frequency channel.
The first
is a
low-level
wide-band
output
(also
usable
as
IF Input) and
is
mainly
intended for
driving
the
companion
Panoramic
Display
Unit (Model
EP17R)
via
an
external
IF
Converter.
Bandwidth
at
this
output
is
of
the
order 1
MHz
at
the higher
frequencies
in
the tuning
range.
The
other
output
is
taken
from
the
final stage
in the
IF
Channel,
bandwidth
being
determined
by
the
setting
of
the panel
selectivity
switch. Video
out-
put
is available
on
both
AM and
Fid.
Audio facilities
include
outputs for
external
speaker,
telephones and remote
lines,
the
latter
being
restricted
to
permit
direct
connection to Post
Office
circuits.
A
separate level
control
is
used
for
the line
amplifier
which
is
totally independent
of
the local monitor
channel.
Frequency
response
is
maintained within
6dB
up
to
10 kHz
and
a
built-in monitor
speaker is
fitted for
convenience
in rack-mounted
installations.
Other
standard
features
include
an
internal crystal
calibrator (modulated
10 MHz
markers), a
tuning
meter
and
a
carrier-controlled
muting system.
Panel controls
comprise
Tuning
(gear-drive,
flywheel-loaded
with
a
ratio
of
approximately 100
si),
Range
Switch, System
Switch
(NOIvMAL
-
CRYSTAL
-
EXT OSC), and
a
combined Mode/Supply
Switch.
Separate
switches
are
provided
for
Selectivity,
AGC, Muting,
Calibrator
and
Monitor
Speaker? a
mechanical
cursor
shift
is
fitted
for
correcting scale errors when
calibrating.
Pre-set
Line
Level,
Meter
Zero and
Muting controls are located at
the
rear
of
the
set
together
with
a
miniature
toggle
switch for closing
down
the front-end
converter when
using
the
IF
Input facility.
The
receiver
is
equally
suited to
bench
or
rack-mounting and though weighing
less
than 20
lb
is
extremely
robust
constructionally.
Printed wiring techniques are employed
for
most
parts
of
the
circuit,
using
high-grade
components throughout. Internal
layout
is
arranged
for
easy
access
in
the
event
of
servicing
being
necessary.
External
appear-
ance is
in keeping
with
modem
trends and
finish
is
to
the
highest standard.
Sole
Manufacturers
s -
EDDYSTOHE
RADIO
LIMITED
,
ALVSCHURCH
ROAD, BIRMINGHAM
31,
ENC-LAHD.
Issue
1 .
August
1967
.
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