User manual MCINTOSH MR 78

[. . . ] THE McINTOSH MR 78 SOLID STATE FM/FM STEREO TUNER Reading Time 32 Minutes Price $1. 25 Your MR 78 FM/FM Stereo Tuner will give you many years of pleasant and satisfactory performance. If you have any questions concerning the operation or maintenance of this instrument, please contact: CUSTOMER SERVICE Mclntosh Laboratory Inc. 2 Chambers Street Binghamton, New York 13903 Phone: 607-723-3512 CONTENTS GUARANTEE INSTALLATION HOW TO CONNECT BACK PANEL INFORMATION FRONT PANEL INFORMATION LISTENING TO THE MR 78 TUNER PERFORMANCE LIMITS TYPICAL PERFORMANCE CHARTS TECHNICAL DESCRIPTION BLOCK DIAGRAM 1 2, 3 4, 5 6 6, 7 8 9 10, 11 12, 13, 14 15, 16 Take Advantage of 3 years of FREE Factory Service . Fill in the Application NOW. GUARANTEE Mclntosh Laboratory Incorporated guarantees this Instrument to be capable of performance as advertised. [. . . ] The indicator will not light on noise pulses or interference. The STEREO FUNCTION indicator will light regardless of the MODE switch setting. MODE SWITCH The MODE switch has three settings. STEREO ONLY - Only stations broadcasting the 19, 000 Hz pilot signal for stereo can be heard in this position. All monophonic stations and background noises are suppressed. The TUNING meter and SIGNAL STRENGTH meter function will indicate monophonic broadcasts when tuning but no program will be heard from the loudspeakers. MONO-In this position of the MODE switch, all broadcasts will be heard monophonically. The automatic stereo switching is bypassed. When the receiving antenna is rotated to minimize multipath interference, the meter indication will decrease and become steady. If the multipath interference is eliminated, the meter indication will be near zero and steady. SELECTIVITY SWITCH AND INDICATOR The SELECTIVITY switch allows stereo reception even under severe receiving conditions. Setting the 7 SELECTIVITY switch to NORMAL connects a very low distortion 8-pole Rimo filter in the IF circuit. Use the NORMAL position of the SELECTIVITY switch for listening to local broadcasts. Setting the SELECTIVITY switch to NARROW adds a sharp 8-pole Rimo filter to the NORMAL IF filter to yield a low distortion (less than 0. 2%), highly selective 16-pole composite IF filter. Use the NARROW position of the SELECTIVITY switch to reduce any interference during the reception of distant stations. Setting the SELECTIVITY switch to SUPER NARROW adds a 4-pole 4-zero crystal filter to the two previously mentioned filters. Use the SUPER NARROW position to receive stations from distant cities which are on channels adjacent to local stations. There may be usable signals never heard before with ordinary FM tuners. The IHF Adjacent Channel Selectivity characteristics are: NORMAL 7 dB; NARROW 22 dB; and SUPER NAROW 55 dB. SECONDARY CONTROLS On the top of the chassis behind the front panel is the DIAL SCALE INTENSITY Switch and ANTENNA MATCH SELECTOR switch. DIAL SCALE INTENSITY SWITCH Adjust the brightness of the dial lights by means of this switch. Set the switch to BRIGHT for maximum panel light; set the switch to DIM for subdued dial light. [. . . ] Mclntosh has a US patent on this new FM detector. The resistors R1 and R3 form a Wheatstone bridge in combination with the two transmission line sections. The RF voltages E1 and E2 at the junctions of the resistors and the transmission lines will vary with frequency in such a manner that their RMS arithmetic difference (E1 - E2) is a straight-line function. Thus these RF voltages are peak rectified by an amplitude detector, and the difference taken, producing a distortionless recovery of the FM information. Ordinary stereo filters use a single capacitor. [. . . ]