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McIntosh MI-3

Maximum Performance Indicator (1970)

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McIntosh MI-3


The McIntosh MI-3 is five laboratory instruments combined into one compact instrument.

It is a professional oscilloscope, relative signal strength indicator. calibrated FM deviation meter, calibrated balance meter. and phase indicator. These instruments are used by FM stations to determine the best possible performance for your listening enjoyment.

The McIntosh MI-3 Maximum Performance Indicator makes it easy for you to attain professional broadcasting quality FM listening.

It shows you what you need to do to improve your system's overall performance. It is designed to be used with an FM tuner and stereo preamplifier.

When the MI-3 is used with an FM tuner it will 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. The Maximum Performance Indicator makes it easy to know when the FM antenna is oriented for the best reception of any station.

To show multipath reception the MI-3 displays instantaneous signal strength versus frequency deviation. Signal strength is shown as vertical deflection of the indicator display beam. Frequency deviation is shown as horizontal deflection. Multipath reception appears as a peak or valley in the MI 3 picture tube display


Signal strength (vertical) input: 700mV

Dimensions: 16 x 5-7/6 x 13 inches

Weight: 23 lbs

Finish: anodized gold and black gloss front panel


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This website is not affiliated with or sponsored by McIntosh. To purchase MI-3 spares or accessories, please contact the company via their website or visit an authorised retailer.