Fig. 5-MODE SELECTOR in the MPX STEREO position.
MPX STEREO:
In this position the output of the multiplex adapter
(that can be installed on the chassis in the prepared
space) connects to the jacks marked STEREO OUT on
the back panel. The STEREO OUT jacks are not controlled
by the volume control. The right channel program is also
connected to the jacks marked MONO OUT and is con-
trolled by the volume control.
Fig. 6-MODE SELECTOR in the EXT. STEREO position.
EXT STEREO:
In this position the MR-65 is used for stereo broad-
casts of FM-FM stereo or FM-AM stereo. The switch con-
nects the jack STEREO IN-LEFT to the jack STEREO OUT-
LEFT without amplification or volume control. The STEREO
OUT-RIGHT jack is connected to the MR-65 FM program
without the volume control. For FM-FM stereo another
FM tuner can be plugged in the jack STEREO IN-LEFT.
The MR-65 supplies the right channel program while
the external tuner supplies the left channel program.
Similarly for FM-AM stereo, the AM tuner can be plugged
in the STEREO IN-LEFT jack to supply left channel pro-
gram while the MR-65 supplies the right channel program.
Again in this position the right channel program from
the MR-65 is connected to the MONO OUT jacks through
the volume control.
AUTO. FREQ. CONTROL
Fig. 7-The AUTOMATIC FREQUENCY CONTROL
The amount of AFC can be varied from off to full on
by turning this control. Turned to the extreme left posi-
tion the AFC is off. Turned to the extreme right position
AFC is maximum.
The automatic action of the AFC is an exclusive
Mclntosh development. The AFC is electronically delayed
to allow tuning without AFC. When tuning is complete,
AFC is automatically restored.
MUTING
Fig. 8—Two position MUTING switch.
Between station noise is suppressed while tuning
when this switch is turned to the IN position. Ultra-sonic
muting, developed by Mclntosh, electronically turns off
the between station noise including the noises usually
heard when tuning in and out of a station.
BACK PANEL FACILITIES
Fig. 9 —Rear of chassis showing jacks, terminals, and adjustments.
MPX OUT
The unfiltered output of the MR-65 is connected to
the MPX OUT jack to feed an external multiplex adapter.
The FM program is always connected to this jack and is
not affected by the front panel switching.
MUTE ADJ
The ultra-sonic muting feature of the MR-65 is de-
signed to suppress noise between stations. The thres-
hold of the muting is adjusted at the factory using precise
measuring instruments. We do not recommend casual
adjustment of this control. In the event it is necessary to
adjust the threshold, turning the MUTE ADJ control to
the right lowers the threshold of muting and turning the
control to the left raises the threshold.
MON OUT
All monophonic programs and all right channel stereo
programs tuned in on the MR-65 are connected to the
MONO OUT jacks. These jacks are connected in parallel
and are fed from a low impedance feed back amplifier.
The front panel volume control adjusts the program level
fed to these jacks. The output level is variable up to 4
volts depending on volume control setting.
STEREO IN
These jacks connect a separate tuner through the
front panel switching for FM-FM stereo. (See the para-
graphs POWER OFF and EXT STEREO under MODE
SELECTOR on pages 2 and 3 for a complete explanation.)
STEREO OUT
A low impedance feed back amplifier without volume
control feeds the output jack marked RIGHT. The LEFT
jack program connection depends on the setting of the
MODE SELECTOR (See MODE SELECTOR page 2.) The
output voltage of the RIGHT jack is approximately 4 volts.
3