McIntosh MR 74, Owner'S Manual

Page 1: ...THE McINTOSH MR 74 SOLID STATE AM FM FM STEREO TUNER READING TIME 28 Minutes Price 1 25 ...

Page 2: ......

Page 3: ...r all Mclntosh instruments at normal service rates To receive the free service under the terms of the SERVICE CONTRACT the SERVICE CONTRACT CERTIFICATE must ac company the instrument when taken to the service agency 3 Always have service done by a Mclntosh authorized service agency If the instrument is modified or damaged as a result of un authorized repair the SERVICE CONTRACT will be cancelled D...

Page 4: ... of the template clear any shelves partitions or existing equip ment located behind the panel With the tem plate in place mark the six A and B holes and four small holes locating the corners of the cutout Next join the four corner marks with pencil lines the edge of the template may be used as a straight edge 2 DRILL HOLES Holding a drill perpendicularly to the panel drill the six A and B holes us...

Page 5: ...atches in and continue to slide the instrument until its front panel is flush with the cabinet panel At the bottom front corners of the instrument are the PANLOC but tons Depressing the PANLOC buttons will lock the instrument firmly in the cabinet Depres sing the PANLOC buttons a second time will release the instrument You can then slide the instrument forward to the adjust position De pressing th...

Page 6: ...ception Connect the leads from the UHF VHF TV antenna to the 300 ANT red terminals CONNECTING AN INDOOR DIPOLE ANTENNA The flexible folded dipole antenna 300 ohm is for use in urban or high strength signal areas Connect the two leads from the dipole to the 300 ANT red terminals The flexibility of the thin flat wire assembly permits it to be placed under a rug tacked behind the stereo or placed in ...

Page 7: ... quality loopstick antenna is provided It can be rotated for maximum performance optimum signal reception or minimum interference The antenna is rotatable through nearly 180 degrees LEFT SPEAKER RIGHT SPEAKER 5 PREAMPLIFIER POWER AMPLIFIER ...

Page 8: ...o 160 2 FM Marked 88 to 108 3 Logging scale Marked 0 to 100 The logging scale can be used to accurately re tune any station You may find it easier to keep a record of your favorite stations by use of the logging scale A small portion of dial pointer has been illuminated to increase the ease of tuning INDICATORS The MR 74 has four indicators on the dial panel STEREO indicator MULTIPATH indicator SI...

Page 9: ...16 pole composite filter Use this switch position to reduce interference on distant stations FM MUTING Muting suppresses the background noise and hiss normally heard between stations Turn the control to either LOCAL or DISTANT position for muting Weak stations that may not override noise and interference are also suppressed by the muting In the OUT posi tion the muting is turned off to allow FM tu...

Page 10: ...und noise With muting in operation signals that are marginal are automatically suppressed To hear these weaker stations set the FM MUTING switch to OUT Usually the listening quality will be rather poor due to the background noise If an antenna rotator is used rotate the directional antenna for best reception as shown by the SIGNAL STRENGTH and MULTIPATH indicators Adjust the VOLUME control to desi...

Page 11: ...e STEREO SEPARATION 35 dB at 1 000 Hz STEREO FILTER 10 dB noise reduction in Position 1 20 dB noise reduction in Position 2 AM SECTION SENSITIVITY 75 µV external ant SIGNAL TO NOISE RATIO 55 dB at 100 modula tion 45 dB minimum HARMONIC DISTORTION 1 at 30 modulation SELECTIVITY ADJACENT CHANNEL 35 dB in NORMAL position 45 dB in NARROW position IMAGE REJECTION 65 dB 540 kHz to 1600 kHz FREQUENCY RES...

Page 12: ...LTS ACROSS 300 OHMS 10 000 FM IF CHARACTERISTIC 0 10 20 30 40 50 60 70 80 90 FM HARMONIC DISTORTION FREQUENCY IN Hz 10 100 1000 10000 20000 100 0 100 200 300 400 10 FREQUENCY IN kHz AMPLITUDE RESPONSE IN dB PER CENT HARMONIC DISTORTION 3 2 1 0 0 10 20 30 40 50 60 70 RELATIVE OUTPUT IN dB ...

Page 13: ...NCY RESPONSE 20 100 1000 10000 20000 FREQUENCY IN Hz AM SELECTIVITY AT 1000 kHz 0 20 40 60 80 85 100 1030 1020 1010 1000 990 980 970 11 RELATIVE OUTPUT IN dB FREQUENCY IN kHz 0 10 20 30 40 RELATIVE OUTPUT IN dB ...

Page 14: ...transistor is internally protected by back to back diodes against incoming transients Use of MOSFET s greatly reduces the cross modulation products over a wide dynamic range A wide dynamic range permits the input cir cuits to accept extremely strong signals without overload Since both RF amplifiers have insulated gate configurations external neutralization is not required This design results in a ...

Page 15: ...o switching is inactive assuring optimum signal to noise ratio The stereo switching circuit has been designed so that noise will not activate it 13 FM muting in the MR 74 operates by detecting ultra sonic noise When noise is present the muting circuit can be activated or defeated by the use of the muting switch on the front panel The STEREO FILTER is provided to reduce noise when listening to weak...

Page 16: ... low distortion wide frequency response and excellent stability Each audio amplifier delivers 2 5 volts to the FIXED OUTPUT jacks A second pair of outputs are available where level can be varied by the VOL UME control POWER SUPPLY Special design attention has been given to the power supply section Three separate power supply circuits are used The first is a 24 volt regulated sup ply This 24 volt r...

Page 17: ...Block Diagram ...

Page 18: ...FM STATION LOG CALL LETTERS FREQUENCY LOCATION ANTENNA DIRECTION CALL LETTERS FREQUENCY LOCATION ANTENNA DIRECTION 16 ...

Page 19: ......

Page 20: ...McINTOSH LABORATORY INC 2 CHAMBERS ST BINGHAMTON N Y 13903 607 723 3512 Design subject to change without notice Printed in U S A 038 839 ...