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mechanical
installation
a)
HEAT DISSIPATION
(VENTILATION):
In
common
with
other electronic
equipment,
the
HF~
12
produces consider-
able heat
in
normal operation. Unless continuous
and ade-
quate
air
flow
is
obtained around
the
heat producing ele-
ments, these
elements
will
over-heat and
their useful
life
will
be
greatly curtailed.
It
is
useful to
understand the process
of
convection
where-
by heat
is
removed
in
judging the
suitability
of
a
location.
Air
heated by
the
heat-producing elements expands
and
rises;
cool
air
is
drawn
from beneath
to
take the place
of
the
heated
air.
In
this
manner,
a stream
of
air
Is
set in
motion
which
continually
removes heat
from the
ampli-
fier.
(In
particular,
we
are
mainly concerned with
the
major heat-producing elements;
the
two EL84
output tubes
and
the
EZ81
rectifier
tube.)
If
there
is
any impediment
to
or constriction
of the
air
flow, the
essential
process of
heat
removal
will
be
adversely affected.
Adequate
ventilation
will
be provided
if
the amplifier
is
installed
in
an open-back
console provided
that the top
of the
amplifier
is
spaced
at
least
two
inches
below any
shelf
mounted above
it.
If
the cabinet
is
enclosed
at the
rear,
provide
several large holes or
slots
as
low
down
and
as
high
up
in
the
cabinet
back
as possible.
As
an
alter-
nate, holes
may
be provided
in
the
sides,
bottom,
or top
of the
cabinet.
The
important
thing
to
remember
is
that
effective ventilation requires provision
for
cool
air to
en-
ter
at the
bottom and
hot
air
to
leave
at the top.
If
the amplifier
Is
not
installed
in
a
console,
it
may
be
situated
on an
open
surface or
on
a
shelf of
a bookcase.
Four rubber feet are also
provided
so that
the amplifier
wi
1
not
mar
the surface of furniture
on
which
It
is
placed.
b)
EASY
ACCESS
TO CONTROLS:
Mount
the amplifier
at a
height
which
will
permit easy manipulation of
the
con-
trols.
Tuner
controls
should
be
located nearby.
c)
ACCESSABILITY
TO
PARTS:
Tubes
are the
most
fre-
quently replaced Items
In
electronic
equipment.
If
the
amplifier
is
installed
in
a console,
sufficient
space
should
be
alloted
to
reach
and remove any
tube
in
the amplifier.
Furthermore, input
and output
terminals of the amplifier
should
be
accessible
to
permit easy interchanging
of
sys-
tem
components
for
comparison, and connection
or dis-
connection
of a portable
tape recorder
which
is
stored
a-
way when
not
in
use.
If
antennas
are strung
around
the
back
of the
console
in
which
the amplifier
is
installed,
arrange
them
so
they
will
not
interfere
with access
to
the
amplifier.
d)
ACOUSTICAL
ISOLATION:
If
amplifier
and
speaker
are installed
in
the
same
cabinet
(not
recommended),
pro-
vide
sufficient
separation
to
minimize mechanical
speaker
vibration
reaching
the amplifier.
The
minimum
separation
Is
about
one
foot.
CONSOLE
MOUNTING
a)
Operations on console
front
panel preliminary
to
am-
plifier
mounting
:
(1)
Tape
the
panel template provided
to
the
face
of the
console
so that the
top of the
mounting
surface
line
on
the
template
is
level
with
the top of the
amplifier
mounting
shelf.
(2)
Use an awl
or a
nail
to
pierce the centers
of the four
5/8" diameter
holes
for
the
controls, the
3/8"
hole
for
the
viewing
of the
pilot
lamp,
and
the
two
small holes
for
mounting
the control plate,
to
transfer their
locations
to
the
console panel beneath.
(3)
Remove
the panel template.
(4)
Drill
the holes
for
the
panel
controls
and
the
pilot
viewing
hole
(the
two
small
holes
which have been marked
are
for
wood
screws).
b)
Amplifier
mounting
in
console
:
(1)
Pull off
the
con-
trol
knobs.
(2)
Remove
the control plate,
which
is
at-
tached
to
the
bezel
by two
screws.
(These
may
be
dis-
carded
since they are unsuitable
for
attaching
the control
plate
to
the
console panel
and two
^4X3/8
wood
screws
have been
supplied
for
this
purpose.)
(3)
Fasten the
con-
trol
plate
to
the
console panel with the 2 ^4
X
3/8
wood
screws.
(4)
If
the rubber feet
have been
inserted
in
the
bottom
plate,
remove
them. (They
may
be
pried
out with
a
thin
screwdriver.
)
(5)
Remove
the four screws that fasten
the
bezel
to
the side pieces
and remove
the
bezel,
which
is
not used
in
console mounting.
(6)
Place
the unit
on
the
mounting
shelf
and
slide
it
as far
forward
as possible, so
that the controls
penetrate
the
panel
holes as
for as
pos-
sible.
(7)
Place
a
knob on each
control, pressing
each
knob
toward
the
chassis firmly so that
each
control shaft
enters fully into
its
knob.
(8)
Draw
the
chassis
back evenly
and
carefully
until
the
back
rims of
all
the
knobs
are equally
spaced
from
the control plate
about 1/8".
(9)
With
a
sharp pencil,
draw
the outline of the side
and
rear
bottom
edges
on
the chassis
shelf.
As
the
bottom
plate
falls
short
of the
full
width by 3/16" on each
side,
draw
new
side
edge
lines
3/16"
inside the original side
edge
lines.
(10)
Now
remove
the
knobs
and
take the
chassis off the shelf.
(11)
Remove
the
6
screws
which
fasten the
bottom
plate
to
the
chassis.
(12)
Place
the
bottom
plate
exactly
in
the
outline
drawn on
the shelf
and mark
the position of the
center hole
on
the
left
side
and
the
center hole on
the
right side.
(13)
Remove
the
bottom
plate
and
drill
each
of the
marked
holes
on
the shelf
to
a diameter
of
1/4".
(14)
Refasten the
bottom
plate
to
the
chassis,
with
the
four of the
six
*8
X
3/8
screws previously
removed,
using
the
two
holes at the rear
and
the
two
holes at the
front
of
the
chassis. (15)
Replace
the chassis
on
the
shelf,
position-
ing
it
exactly
in
the outline
previously
drawn, and
restore
the knobs.
This
time
make
sure that the indicator dot
on
each knob
agrees with
the control position. (16)
From
the
bottom
side of the
shelf, insert
a^8X
1"
screw, with a 1/2"
flat
washer
against the
head, through
both
the
left
and
right side
center
holes.
These screws
engage
the
stamped
nut over
each
hole on
the chassis
flange
and
when
tightened
secure the
chassis
to
the
shelf.
3
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Table of Contents
Troubleshooting
