Specifications
The SPR-4 audio amplifier may be used with an
external
audio source
such
as a tuner.
The level of the external source must be approximately
.08
volts into a 3
K
load .
The received signals
may
be eliminated by
turning the RF GAIN control counter-clockwise or by removing the mute
plug
l
2.8.9 DIAL LAMPS
The DIAL LAMPS switch may be used to tum off the three dial
lamps .
Since
the power required to operate the dial lamps is somewhat greater
than the power required by the rest of the SPR-4, the operating time for a
battery power supply may be extended by turning the lamps off. The on
and off positions of the switch are interchanged when operating with a
DC power
cord
.
2.8.10
ANTENNA JACK
The antenna
jacks
mate with a standard phono fitting. A
special
antenna
fitting (a pin with a spring clip
attached
) is supplied with the SPR-4 and
may be used by inserting it into the antenna
jack.
The antenna
lead
-in
is then
connected
to the clip.
2.8.11 ACCESSORY CRYSTAL INSTALLATION
The top of the SPR-4 cabinet must be removed in order to install
addition-
al
crystals .
This is accomplished by removing the top row of screws on
both
sides
of the set.
Also, disconnect the
table
from the speaker
jack.
Be sure the power
tord
is disconnected.
The top of the cabinet may now
be
removed .
At the bottom of
each
segment of the
crystal
selector
dial
is a small num-.
ber (0
-
23
)
which corresponds to a particular
crystal
socket .
The
crys-
tal location diagram which is located on the
chassis
behind the
crystal
sockets indicates the number of
each
socket. No
crystal
is required for
reception
of 15 0
-
500 kHz,
therefore there is no
crystal
socket numbered
zero .
Install
the accessory
crystal
in
one
of the empty sockets .
Locate
the
appropriate
crystal
dial
decal
from the sheet supplied with the
crystal.
Remove the
decal
from the sheet by cutting
along
the appropriate
lines
with a pair of scissors .
Remove the
backing
from the
decal
and install it
in the dial sector with the
same
number as the
crystal
socket
used.
Re-
place the cabinet top and the speaker
table.
On certain
ranges there
are spurious interna1 signals which are
unavoid-
able in this double conversion, super-heterodyne receiver. These are
due to outputs of interna1 conversion oscillators. There are five
frequen-
cies
that should be avoided if possible. These are; 5.222 MHz, 5.595
MHz, 5.695 MHz, 9.963 MHz, and 15.334 MHz.
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8
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