MULTIPATH/ TUNING INDICATOR MI-2 GENERAL DESCRIPTION 1 TECHNICAL DESCRIPTION 3 Specifications TABLE OF CONTENTS 3 FRONT PANEL INFORMATION 4 BACK PANEL INFORMATION 5 INSTALLATION 6 CONNECTING Connecting to Mclntosh MR67 Tuner Connecting to Mclntosh MX110 Tuner-Preamplifier with Z or X Serial Numbers Connecting to Mclntosh MX110 Tuner-Preamplifier with M Serial Numbers Connecting to Mclntosh MR65B Tuner Connecting to Mclntosh MR65 and MR65A Tuner Connecting to Mclntosh MR66 Tuner Connecting to
MI-2 MULTIPATH/TUNING INDICATOR GENERAL DESCRIPTION The Mclntosh MI-2 Multipath/Tuning Indicator is designed to be used with an FM tuner to detect and display multipath reception. Multipath reception is the result of a reflected signal arriving at the tuner antenna slightly later than the direct signal. By rotating or repositioning your FM antenna it is possible to reduce the multipath reception.
(2a) (2 b) (2c) (2d) Figure 2. Various Forms of Multipath Reception As They Appear on the MI-2 Display Screen. Such a change may be as little as a fraction of a foot or as much as several feet. The MI-2 is also a very effective tuning indicator: 1) Signal strength is shown by the vertical position of the display trace. The higher the position of the trace the greater is the signal strength. 2) Correct tuning occurs when the display trace is centered horizontally on the screen.
TECHNICAL DESCRIPTION The MI-2 Multipath/Tuning Indicator is essentially an oscilloscope using a three inch cathode-ray tube. Adequate brightness is assured by using a 1350 volt accelerating voltage. To provide a sharp and well defined trace, the MI-2 uses separate focus and astigmatism controls. Two identical direct coupled push-pull amplifiers are used in the horizontal and vertical deflection circuits. Phase shift in each amplifier is held to within a few degrees from D.C.
Power Consumption Fuse 1 Ampere SLO BLO 50 watts, 105 to 125 volts. 50 to 60 cycles. FRONT PANEL INFORMATION Figure 3. MI-2 FM MULTIPATH/TUNING INDICATOR Front Panel. INDICATOR SCREEN The screen is the face of a cathode ray tube. Calibration marks are provided to allow correct positioning of the indicator trace. A correctly tuned station free of multipath distortion will appear as a smooth curve centered on the indicator screen vertical scale.
FOCUS Figure 6. VERTICAL POSITION Control. position the indicator trace can be easily moved to the correct vertical position. For Multipath display the trace is positioned at the bottom reference point (point A). For audio indications the trace is positioned at the center reference point (point B). This shift in position occurs automatically as the Scope Test Control is turned. An internal adjustment labeled "L & R position" is factory preset but can be read justed if needed. Figure 8.
SIGNAL STRENGTH (VERTICAL) MULTIPATH CONTROL This Control adjusts the position of the Multipath trace display along the vertical scale of the indicator screen. DEVIATION (HORIZONTAL) MULTIPATH CONTROL This control adjusts the maximum width of the multipath trace display along the horizontal scale of the indicator screen. LEFT GAIN (VERTICAL) AUDIO CONTROL This control adjusts the maximum vertical indicator trace deflection from a left channel audio signal.
An MI-2 cabinet installation should provide at least 13¾ inches behind the mounting panel for clearance of leads and connectors. Allow inside dimensions of at least 16½ inches in width and 5 inches in height for adequate air circulation. The back panel of the MI-2 cabinet should be left as open as possible for best ventilation. Avoid mounting the indicator directly over a power amplifier. Adequate ventilation will insure your indicator a long and trouble-free life. Figure 11.
through the wood panel, and into the fasten ing strip attached to the inside of the panel The screws should be moderately tightened. Figure 14. Securing Mounting Strips To Installation Cutout. panel thicknesses. Insert a screw in the center holes ( " B " holes). Tighten so that the screw pulls into the wood. 5.
DIRECTIONAL FM ANTENNA ROTATOR TO TP I TO II7V AC OUTLET STEREO POWER AMPLIFIER Figure 16. MI-2 Typical Hook-Up.
CONNECTING TO MclNTOSH MX110 TUNER-PREAMPLIFIER WITH M SERIAL NUMBERS Remove capacitor C130 (.005 MF) connected between the test point and ground. Solder the center lead of a 1 foot low-loss shielded cable to the junction point of R139 (10K) and C125 (.1 MFD). Solder the outer shield of the cable to the tuner chassis ground. Use one of the 1 foot long low-loss shielded cables, stripped and tinned on one end, (female jacks on the other end) supplied with the MI-2.
CONNECTING TO ALL OTHER TUNERS Connect a low-loss shielded cable from the input to the first FM limiter through a 100 K resistor, to the Signal Strength (vertical) Input on the MI-2. Connect a low-loss shielded cable from the discriminator output (ahead of the deemphasis network) to the Deviation (horizontal) Input on the MI-2. OPERATING INSTRUCTIONS MULTIPATH AND TUNING INDICATION 1. Turn the MI-2 power switch to ON. 2. Turn the SCOPE TEST switch to TEST. 3.
Figure 19. Irregular Pattern With Vertical Traces Indicating The Presence of Multipath. 2. Adjust the SIGNAL STRENGTH (vertical. Multipath control on the back panel until the pattern on the indicator screen is about ¾ inch from the top of the vertical scale. The 19KC carrier from a station broadcasting multiplex stereo will keep the Indicator trace from closing down to a dot with no station modulation. Figure 20. 19KC Pilot. SIGNAL STRENGTH MULTIPATH CONTROL 1.
tered horizontally on the Indicator screen. Calibration lines are provided on the Indicator face for centering purposes. 4. Adjust the vertical position control until the trace dot is positioned at the bottom of the center vertical scale. Figure 2 1 . Trace Dot Positioned at Center of Screen. 5. Adjust the INTENSITY and FOCUS controls for a sharp and clear trace dot. 6. Turn the SCOPE TEST switch to L & R Audio. 7. Set the tuner to an FM Station broadcasting a monophonic program. 8.
FM STATION LOG STATION 14 DIAL FREQ.
FM STATION LOG STATION DIAL FREQ.
Your MI-2 will give you many years of pleasant and satisfactory performance. If you have any questions concerning the operation or maintenance of this tuner please contact: Customer Service Mclntosh Laboratory Inc. 2 Chambers Street Binghamton, New York Our telephone number is 723-5491. The direct dial area code is 607. GUARANTEE Mclntosh Laboratory Incorporated guarantees this equipment to perform as advertised.
LABORATORY 2 CHAMBERS STREET, BINGHAMTON, N. Y. Made in U.S.A. P h o n e - A r e a Code 607-723-5491 INC.
