PAGE
2
EICO
MX99
IN
ST R U CTION BOOK
SECTION I. GENERAL DESCRIPTION
*
The new
EICO
MX-99 Multiplex
Autodaptor
employs
an
original
method of zero
phase shift, filterless
detec-
tion
of multiplexed signals.
The unit automatically
delivers
stereo on a stereo
broadcast signal,
and mono
from a mono signal
without spurious signals
in either
case. The
stereo signal is automatically
gain-balanced
and the mono
signal
is
automatically equal
from
both
outputs without
adjustment. An indicator lamp
turns
on when the station selected is
broadcasting multiplex
stereo.
The design features
freedom from phase
distorting
filters
in either the main
or sub channel
paths which
cause loss of separation.
Nevertheless this
design
provides
the required,
or better-than-required,
sup-
pression of all
spurious signals including
SCA
(67kc)
background
music carrier, reinserted
38kc sub-car-
rier, 19kc
pilot carrier,
and
all
harmonics
thereof.
This is achieved partly
through an original
technique
for deriving
the left and right signals,
and partly
by
sharp
ultrasonic filters after the
signals are
derived.
All
of
the foregoing
is
very
important for high quality
tape recording,
where spurious
signals can beat
against
the tape recorder
bias oscillator and
result in audible
spurious
tones
in
a recording.
This adaptor will
syn-
chronize with
any usable output
from
the
FM
tuner
and will demodulate
without significant
distortion tuner
(composite signal)
as high as 5 volts
peak-to-peak.
The MX-99 is self
powered, and includes low
impedance
cathode follower outputs. External
controls
include
an oscillator
turn-off switch to
permit inter-
ference-free
listening to mono
stations having low
sub-carrier
frequency SCA store-casting
and a separ-
ation control.
A separation
of
30db
between
channels
is typical and an overall
gain of unity is provided from
input to output
on
both
stereo and mono.
The MX-99
is designed
for all
EICO FM
equipment
(HFT90, HFT92,
ST96), and any other component quality,
wide band
FM
tuner provided with
a
multiplex
output.
Tubes:
2-12AU7, 1-12AT7, 1-6AU6,
1-6D10, 1-6X4
and 6 diodes
Size
(HWD):
3-7/8"
x
9-1/8"
x
6-3/8"
Weight:
7
lbs.
Cover: OPTIONAL
*
Patent
Pending
SECTION II.
CABINET
INSTALLATION
2-1.
GENERAL
1.
Mount
horizontally
on a
well-braced
shelf. The
stock thickness of the wood panel
may not exceed
3/4".
2.
Do
not
remove feet for mounting. Air
must be
allowed
to enter through the
perforations in the bottom
plate
to avoid overheating.
3.
To
avoid over heating when stacking
components
mount the tuner below
the
amplifier
with the
MX-99
alongside the tuner.
Any
shelf above the
MX-99 must
be spaced at least 2 inches
away.
Allow
at
least
a
1-
inch
tolerance
on
either side
of
the
unit.
4.
Leave the back of the
cabinet entirely
open.
2-2.
PREPARATION
OF
UNIT
1.
Loosen the left and right
side pairs
of screws
(4
in all) that
fasten the bottom plate
and cover
to the
chassis,
just enough to permit the
cover and
bottom
plate
to slide backward
or forward in
the
3/4"
chassis
slots.
2.
Push both
cover and bottom plate
back
as far
as
they
will
go (3/4"). The
screws that have
been
loosened will
move from the
front to the rear
ends of
the
slots in the
chassis.
3.
Detach the knob from
the separation
control
shaft. Then
remove
the 2 screws, that
fasten the panel
to the
chassis, one at the left
of the
NORMAL-MAIN
CH
switch
and the other
at
the
right of the
ON-OFF
switch.
Take panel
off and set it
aside. The unit
is
now prepared for
cabinet installation.
2-3.
PREPARATION
OF
CABINET
1. Two
templates are provided,
one for the cabinet
shelf
and the other
for the
cabinet panel.
The shelf
template
is
used to
locate
exactly
two holes
that are
to
be drilled in
the shelf.
The panel template
is used
to locate exactly
the required
rectangular
cut-out.
The
two templates
must be used
together as indicated,
as
there
is an exact
relationship
between the
locations of
the shelf holes
and panel cut-out.
2. To
use the shelf template,
cut it
or
fold
it back
exactly along the
dashed line.
Remove the shelf
from
the cabinet
and line
up
this
dashed line
on
the
template
with
the front edge
of the shelf, positioning it
also along
the edge
to leave
at least
1
clearance
on each
side.
Tape the template in position
and
use a center punch
to
mark the
centers of the two
holes to
be
drilled.
If
the
shelf can not be removed, place
the template in
a
similar manner on
the top side of the shelf if
there
is
room to drill from the
top side, or on the
under side
of shelf if
there is room only to drill
from the under
side.
If the template is
used on the underside
of the
shelf,
mark the rear
edge of the shelf
at
the
points
where the extended heavy lines
on the template
hit the
rear shelf
edge. After the
holes are
center-punched,
remove
the
template
and drill
carefully through
the
punched centers
to a
diameter
of
1/4”.
If the shelf
has been removed
for the drilling
operation, now re-
mount it. Finally,
replace the
shelf-template in exactly
its former
position on the top-side
of the shelf
and
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