Specifications

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 astig-
matism 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. throughout the operating fre-
quency range. Phase differences between
vertical and horizontal amplifiers are also
held to within a few degrees.
The high-voltage power supply uses a 6W4
tube rectifier. Two low-voltage supplies use
selenium rectifiers, two gas filled regulator
tubes and an electronic voltage regulator.
The operating voltages from these supplies
are carefully regulated over a wide range of
power line variations. This design feature
assures a steady indicator trace despite
changing line voltage.
For Multipath display the horizontal de-
flection voltage is obtained from the tuner
discriminator output ahead of the de-empha-
sis network. This voltage is proportional to
the frequency deviation of the FM transmis-
sion. The maximum width of the indicator
screen is designed to correspond to approxi-
mately plus and minus 75 kilocycle deviation
of the FM transmitter.
The horizontal multipath input is con-
nected through the Deviation Input jack and
Sensitivity
Signal Strength (Vertical) Input
0.37 Volts per Cm.
Left Gain (Vertical) Input 0.37 Volts per Cm.
Deviation (Horizontal) Input
0.27 Volts per Cm.
Right Gain (Horizontal) Input
0.27 Volts per Cm.
Dimensions
Front panel 15
5
/
8
inches x 5
1
/
8
inches; overall
depth of chassis behind front panel, 11½
inches; clearance in front of mounting
panel including knobs, 1 inch.
the Deviation (horizontal) calibration control.
For multipath display the vertical deflec-
tion voltage is obtained from the tuner Auto-
matic Gain Control circuit at the input to the
first limiter. This voltage is proportional to FM
station's instantaneous signal strength. How-
ever the average proportionality is exponen-
tial. Because of the exponential characteris-
tic, a weak station will produce adequate
vertical deflection. A powerful local station
should position the center of the indicator
trace about half to three quarters of an inch
below the top of the vertical scale.
The vertical Multipath Input is connected
through the Signal Strength Input and the
Signal Strength (vertical) Calibration Input
Control.
For L & R Audio display the horizontal de-
flection voltage is obtained from the right
channel output of a tuner, a preamplifier or
even a power amplifier. This deflection volt-
age is connected through the Right Audio
Input and the Right Gain Control.
For L & R Audio display the vertical deflec-
tion voltage is obtained from the left channel
output of a tuner, a preamplifier or a power
amplifier. This deflection voltage is con-
nected through the Left Audio Input and the
Left Gain Control.
With a normal loudness monaural signal
both audio input controls are adjusted for
equal deflection of the display trace. At this
point the trace will lie on the L+R line if the
two signals are in phase or the L-R line if
they are 180° out of phase.
Tube and Semiconductor Complement
1—3RP1, 3 inch Cathode Ray tube.
4—6U8, Horizontal and Vertical Deflection
amplifiers
1—6U8, Electronic Voltage Regulator.
1-6W4, High Voltage Rectifier.
2-OB2, Voltage Regulators.
6—Selenium Rectifiers, low-voltage supply.
Weight
Chassis only,22pounds.
In shipping carton, 29 pounds.
Finish
Anodized gold and black glass front panel.
MI-2 SPECIFICATIONS
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