Quick Start - AEA VIA Bravo MRI Operating Manual

2 Quick Start

Connect the power pack to a wall outlet, the other end of the power pack plugs into the
jack located on the top panel of the VIA Bravo MRI – to the right of the coax connector.
Momentarily press the ON key. You should see the AEA marquee screen for a few
seconds, and then a graph will appear. The factory default sets the left plot (thin line) to total
Z (total impedance) and the right plot (hashed line) shows the impedance phase angle.
An open circuit doesn't make an interesting graph, so let's connect a load to the coaxial
connector on the VIA Bravo MRI unit. An open length of coax or a coaxial terminator would
be a good place to start. If you use coax, it will show a resonance at the frequencies
corresponding to a half wavelength multiple. See figure in section 4.5.
Enter a center frequency by pressing a number on the keypad (press the first digit of your
desired frequency). The screen changes to show the digit that you pressed. Press more
digits until your center frequency shows on the display. Press the ENTER key when done.
Note: if you press a wrong digit, just add digits until you have an out of range frequency. The
frequency eventually is erased and you can re-enter your frequency.
Now enter a sweep width by entering digits to get the desired width. Press one of the
WIDTH keys when ready. Due to synthesizer limitations, the sweep widths must be certain
values and the VIA Bravo MRI adjusts your entry to an available sweep width. The VIA
Bravo MRI flashes a brief warning if it changes the sweep width from the number you
entered. The x axis legend displays the lower and upper sweep frequencies.
Press the OFF key. The settings you have entered are automatically saved prior to the
unit shutting off. The next time you power up, these settings will reload, putting the VIA
Bravo MRI in the same state that you last used it in. If you ever want to start the VIA Bravo
MRI with factory preset values, hold the ENTER key while you power up the unit, otherwise,
the unit will load up the settings that were in effect the last time the OFF key was pressed.
Press the ON key again. Connect a load to the coaxial connector to measure its
impedance. Now press the EXAM/PLOT key. The plotting will freeze and a vertical cursor
appears. You may move the cursor with the FREQ keys. The two plot values at the cursor
frequency and the Q of the Z plot are displayed by the three big numbers on the left of the
display. The top number shows the first (left) plot value, the middle number shows the
second (right), the bottom number shows the Q calculated from the Z plot (if Z is plotted).
Using the FREQ keys, move the cursor to a frequency of interest. Pressing EXAM/PLOT a
second time returns to normal sweeping operation, with a new center frequency equal to the
last exam/plot frequency. See paragraph 3.4 for more details on EXAM/PLOT operation.
Refer to the remainder of the manual to find more operational details on these
and other functions.
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