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TO INPUT
HF 81
OF STEREO
TAPE
RECORDER
OUT
cgJ
-=8
STEREO MAG.
CARTRIDGE
FIG. 3
5) AUXILIARY Bl, AUXILIARY
B2: Same as
for AUX-
ILIARY A 1, AUXILIARY A2 above.
6) AM: This input is intended for AM tuner or the AM
output of an FM- AM tuner where the FM and AM sections
are independent.
7) FM:
This input is intended for an FMor FM- AM tuner
where the FM and AM sections are
independent.
8) FM MULTIPLEX:
This input is intended to receive the
output from an FM Multiplex adaptor.
NOTE: A shielded cable with a shielded "
phono-type
plug should be used to connect from each of the above-
2 - PHONO
RECEPTACLE
STRIP
FIG. 4
e) POWER CONNECTIONS: The line cord of the HF-
must be plugged into a house outlet
providing normally
117 volts, 60 cycles AC power.
A convenience recep-
tacle on the rear chassis can be used, if desired
, with a
cube tape to provide
117VAC power to the associated
equipment. This convenience receptacle is not switched
or fused and provides 117VAC at all
time'S""rregardless
of whether the HF-
81 is turned on or off.
HUM ADJUSTMENT
After checking the ampl ifier for proper operation, remove
all input cables to the amplifier and
make the following
control settings which hold throughout the process of
hum
adJustment: INPUT
SELECTOR at
PHONO, FUNCTION
SELECTOR at STEREO, FOCUS
control at 0,
LEVEL con-
trol at 10)'
both TREBLE controls at -
5, both
BASS controls
at 0; the two speaker
systems must be in phase
and placed
near one another for this
adJustment. Next, procede
TO MAG.
INPUT
TO MAG. INPUT 2
mentioned sources to the correspondmg
amplifier input
jack. Unless the source has a low-
impedance output such
as a cathode follower (with which up to 50ft. of cable
can be used), use the
shortest possible connection and
low - capacity shielded cable (cable having
as low as
25mmfd capacitance per foot is available).
d) TAPE OUTPUT 1, TAPE OUTPUT 2: When no
external
amplifier is used in the system,
both these outputs are
available for feeding out to a stereo recorder. When an
external power ampl ifier is used in the system,
TAPE OUT-
PUT 2 is used to feed out to the external power amplifier.
If it is desired to do stereo
recording under the latter
conditions, construct a device such as shown in Fig. 4.
Use low capacity shielded cable for connections.
TO INPUT 2
OF STEREO
RECORDER
TO EXTERNAL
POWER AMPLIFIER
6 ,
follows: With your ear held close to the speakers, insert
the amplifier power plug into the wall outlet and listen
to the hum level. Now pull out the plug and re-
insert it
with the prongs reversed. Choose the prong position with
the least hum. Now connect the tuner input connector to
the amplifier input jack, and with the tuner set
between
stations and the tuner volume control set at a minimum, do
the same with the power plug of the tuner; use either the
117VAC receptacle on the HF- 81 or one receptacle of a
cube tap inserted in the 117V AC receptacle on the HF- 81.
Next)' connect the phono cartridge leads to the MAG.
PHONO
1 and 2 inputs, and, with turntable off and pick-
up arm at the rest position, find the insertion position of
the turntable line cord plug that yields lowest
hum. Fin-
ally, connect the tape head leads to
the TAPE HEAD
and 2 inputs, and
, with the tape deck turned
offl find the
insertion position of the tape deck line cord plug that
re-
sults in lowest hum. When
all of this is completed, ad-
just the hum balance control on top of the amplifier chassis
for least hum.
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