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1 Introduction
1.1 Bravo MRI II Highlights
The Bravo MRI II analyzer measures complex impedances of electrical components,
Filters, antennae, and cables. The results of the measurements are displayed graphically,
with some numeric detail. You can choose to display the impedance from among several
formats. The Bravo MRI II sweeps across a range of frequencies, or operates at CW, either
way the display is continuously updated with new measurement results. This unit has many
applications, including:
1. Tune coils/antennae, filters, and feed systems
2. Measure Z, Angle, Resistance, and/or Reactance of a load
3. Measure Gain/insertion loss and phase of coupled circuits
4. Measure the length of a piece of coax
5. Portable and economic replacement for network analyzer applications that measure S11
and S21.
6. Find resonant frequency and response curve
7. CW signal generator
Two plots may be simultaneously viewed on the same graph. The Bravo MRI II connects
to your PC with the VIA-RTD Software to view results on a multi color, large screen display in
a Smith Chart or X-Y plot format.
The Z altering effects of coax cable can be nulled out, so that the load at the end of the
coax is displayed. The Bravo MRI II operates over a wide range of characteristic
impedances, so you are not limited to measuring 50 ohm systems.
The Bravo MRI II periodically self calibrates during operation when not in “Cable Nulling”
mode. The Bravo MRI II determines when recalibration is required and displays the marquee
screen with a “CALIBRATING” message during the calibration. The unit begins
measurements after a few seconds.
Operator conveniences include: non volatile storage, auditory cues, back lit display,
battery saver options, display contrast adjustment, versatile output displays, and serial port
communications. Internal Batteries (8 AA batteries, not included) power the Bravo MRI II in
situations where wall power is not available.
Included accessories are the VIA-RTD MRI Software, a power pack, a serial port cable,
and a soft case with shoulder strap.
1.2 Using This Manual
Throughout this manual, references are made to FREQ and WIDTH keys. Each of these
keys has an UP or DOWN option. The operator selects the up or down keys depending on
desired results.
Certain words that appear as all capitals (FREQ, WIDTH, ON, OFF EXAM/PLOT,
ENTER) refer to keys on the Bravo MRI II keypad. Other capitalized “words” are acronyms
(VIA, SWR, CW, etc). Capitalized and italicized words (ENTER etc.) refer to keys on your PC
when using the VIA-RTD Software.
VIA is an acronym for Vector Impedance Analyzer, SWR stands for Standing Wave
Ratio, and CW is short for Continuous Wave.