User manual MCINTOSH MPI4

[. . . ] THE MclNTOSH MPI 4 MAXIMUM PERFORMANCE INDICATOR Reading Time 40 Minutes Price $1. 25 Your MPI 4 Maximum Performance Indicator 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: contents GUARANTEE GENERAL INSTALLATION HOW TO CONNECT FRONT PANEL INFORMATION LEVEL SET PANEL INFORMATION REAR PANEL INFORMATION INITIAL SETUP HOW TO USE THE MPI 4 . . . 10-18 CUSTOMER SERVICE Mclntosh Laboratory Inc. 2 Chambers Street Binghamton, New York 13903 Phone: 607-723-3512 Take Advantage of 3 years of FREE Factory Service . [. . . ] An example of a detuned station is shown in Fig. 15: note how the curve is shifted to the left on the screen. Correct the tuning by adjusting the tuners tuning knob to center the trace. FIG. 15 DETUNED STATION Multipath produces several visible symptons on the screen. Peaks or valleys may appear on the curve, as shown in Fig. Note, too, how the entire display is shifted FIG. 13 MULTIPATH F R E E DISPLAY Program modulation causes the trace to expand in a horizontal direction. The pattern, therefore, widens in step with the audio intensity of the program material. Figure 14 shows a display having multipath. The dips and peaks are the result of a reflected signal arriving at the tuner antenna slightly later than the direct signal. FIG. 16 MULTIPATH & DETUNED to the left which indicates a combination of both detuning and multipath reception. In general, a trace that is not smooth suffers from multipath contamination. In severe cases, multipath causes considerable fuzziness or blurring of the overall display. Multipath is most often overcome by changes in antenna direction. For outdoor antennas with a rotator, aiming the antenna in a different direction usually helps. Indoor dipoles or similar antenna may also be repositioned. In all cases, best results are clearly indicated on the MPI 4 screen. F I G . 14 MULTIPATH INTERFERENCE Make sure that the MPI 4 is property set up. Turn the POWER LEVEL switch to the PREAMP position. Set the GAIN control fully counterclockwise (but not to OFF), and the INTENSITY control fully clockwise. By combining displays of strength and modulation, the MPI 4 will not only show multipath, but is, in addition, an accurate tuning indicator Adjust the FM tuning dial until the trace reaches its highest point, while also being centered horizontally on the screen. Depress the STEREO button and check if the spot of light is in the center of the screen. If not, use the HORIZONTAL and VERTICAL controls to center the spot. [. . . ] This half generates a square wave signal that drives the Left-Right switching amplifier. During the LEVEL mode the square wave alternates the column position to the left and right for a two column display. POWER SUPPLIES There are five power supplies in the MPI 4: -5 volts; + and -- 15 volts; 200 volts; and -1000 volts. Each is regulated to assure that the calibrated display does not change due to line voltage variations. [. . . ]