AEA VIA Bravo MRI Operating Manual
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AEA VIA Bravo MRI Operating Manual

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MRI Network Analyzer - 100KHz to 70 MHz

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Summary of Contents for AEA VIA Bravo MRI

  • Page 1 MRI Network Analyzer MRI Network Analyzer - 100KHz to 70 MHz...
  • Page 2 AEA Technology, Inc. All rights reserved. This document and all software or firmware designed by AEA Technolo firmware designed by AEA Technology, Inc. is copyrighted and may not be copied or altered in gy, Inc. is copyrighted and may not be copied or altered in any way without the written consent from AEA Technology, Inc.

  • Page 3: Table Of Contents

    INTRODUCTION ........................1 VIA B MRI H .................... 1 RAVO IGHLIGHTS ......................1 SING ANUAL QUICK START ........................2 OPERATING THE VIA BRAVO MRI UNIT ................3 ......................3 ENTER REQUENCY ......................3 WEEP ANDWIDTH ....................4 REQUENCY ........................5 ........................
  • Page 4 APPLICATIONS AND MEASUREMENT EXAMPLES ............15 ½ ................15 AKE A WAVELENGTH COAXIAL LINE ¼ ................15 AKE A WAVELENGTH COAXIAL LINE .................. 16 OUPLES INTO OWER .................. 16 UNE AN ANTENNA TO RESONANCE ................... 16 EASURE THE LENGTH OF A COAX OPERATION WITH THE VIA DIRECTOR SOFTWARE .............

  • Page 5: Introduction

    You can choose to display the impedance from among several formats. The VIA Bravo MRI sweeps across a range of frequencies, or operates in CW. Either way, the display is continuously updated with new measurement results.

  • Page 6: 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.

  • Page 7: Operating The Via Bravo Mri Unit

    ENTER enough times to push through the menus without altering the settings Whenever you are in a menu, the VIA Bravo MRI lists your choices for keypad entries to help you make your choice and return to measuring.

  • Page 8: Frequency Step Size

    Bravo MRI adjusts your entry to an available sweep width. For example if you enter a 1.000 MHz wide sweep, the VIA Bravo MRI sets the sweep width to 1.000 MHz if the unit is plotting 100 points, but will set the sweep width to 1.600 MHz if the graph is set to 80 points. The VIA Bravo MRI flashes a brief warning if it changes the sweep width from the number you entered.

  • Page 9: Exam/Plot

    The unit is configured with the settings that were in effect when the OFF key was last pressed. If you ever want to start the VIA Bravo MRI with factory preset values, hold the ENTER key while you power up the unit.

  • Page 10: F2 Instrument Properties (Adjustments And Settings)

    10 sweeps after returning to measuring. Also note the maximum intensity is limited and the backlight will only be noticed in dim light conditions. When the VIA Bravo MRI is in a bright environment, the backlight will be washed out.

  • Page 11: Instrument Mode

    3.8.4 Instrument Mode The VIA Bravo MRI Unit can be operated in one of two modes: as a VIA meter or as an SWR meter. The VIA and SWR meters can operate in either CW or sweep mode. The VIA meter can also operate with or without cable nulling.

  • Page 12: F3 Plot Data Properties

    3.9 F3 Plot Data Properties The VIA Bravo MRI can graph up to two plots on the display. More plots may be displayed if you connect the VIA Bravo MRI to a PC running the VIA-RTD software. In addition to the two plots, some information is also displayed numerically. When the plotting width is 100 points, all of the center frequency data is displayed with small digits.

  • Page 13: Right Plot Data

    3.9.1.2 SWR Operation The SWR meter displays impedance in specific formats. Refer to an antenna or radio handbook for detailed information on these quantities. 3.9.1.2.1 SWR SWR is the same as voltage standing wave ratio. This can be used to roughly determine an antenna’s match to its coax.

  • Page 14: Plot Width

    This option is also useful when you are examinig the plots on the VIA Director program, and you just want to check the status of the VIA Bravo MRI from a distance. 3.10...

  • Page 15: Save Operation

    3.11.1 Save Operation Instrument states and data may be saved in EE-prom for recalling at a later time. There are two types of save memories. The first type only saves instrument presets; the other saves both the presets and the plot data. One can use the preset only memory to save instrument states for a number of different antennae.

  • Page 16: Cable Nulling

    3.12.2.1 Open Circuit Reading With the far end of the coax un-terminated (open circuit) press the ENTER key once. A few seconds later the VIA Bravo MRI will prompt you for the next reading….. (a short). 3.12.2.2 Short Circuit Reading With the far end of the coax shorted using the included coaxial short, press the ENTER key once.

  • Page 17: Calibration Cycles

    3.12.3 Calibration Cycles The VIA Bravo MRI will periodically enter a calibration cycle. This ensures the best accuracy over long periods of time. Changing certain sweep parameters can also induce a calibration cycle. Sometimes you may want to enter something into the keypad while a calibration cycle is in progress.

  • Page 18: 100 Point Sweeps

    3.12.6 100 Point Sweeps 3.12.6.1 VIA Mode There are 5 numbers displayed in a small font. The numbers are, in order from top to bottom: 1. Total Z 2. Z angle 3. Resistance 4. Reactance 5. Capacitance/Inductance (see para. 3.12.5.1 ) 3.12.6.2 SWR Mode There a 4 numbers displayed in a small font.

  • Page 19: Applications And Measurement Examples

    4 Applications and Measurement Examples 4.1 Make a ½ wavelength coaxial line To make a coaxial line that is tuned to one half wavelength: 1. Start with a piece of coax that is slightly longer (about 5 to 10%) than calculated. The formula for a ½...

  • Page 20: Load Couples Into Power Line

    Reflection coefficient angle (see paragraphs 3.9.1.2 and 3.9.1.2.4 ). Set the VIA Bravo MRI center frequency to the frequency of interest. Note the RCA reading. By adjusting the sweep width to the widest, and stepping through a number of center frequency values, determine how many positive to negative zero crossings there are below the frequency of interest.

  • Page 21: Operation With The Via Director Software

    Connect the VIA Bravo to the PC with an AEA serial cable (PN 0070-1201) or extra long cable(PN0070-1215). Be sure that the bit rate of the serial port matches the setting selected on the VIA Bravo unit.

  • Page 22: Care And Maintenance

    RF or a Magnetic Field. Do not connect the VIA Bravo MRI to an active transmitter. The VIA Bravo MRI Should Not be allowed to get closer than 3 feet (1 meter) with a 1.5T Coil , and 5 feet (1.5 meter) with a 3T Coil 6.2 External DC Power...

  • Page 23: Limited Warranty

    7 Limited Warranty AEA Technology, Inc., warrants to the original purchaser that the VIA Bravo Analyzer shall be free from defects in material or workmanship for a period of one year from the date of shipment. All units returned to the factory, delivery charges prepaid, and deemed defective under this warranty, will be replaced or repaired at this company’s option.

  • Page 24: In Case Of Trouble

    8 In Case of Trouble Some problems may be identified and solved by the operator. More involved problems will require factory service. To try to solve a problem yourself, refer to the chart below: Symptom Possible cause Refer to paragraph On power up, I hear Display contrast setting 3.8.2, 8.1, 8.1.2...

  • Page 25: Power Induced Failure

    8.2 Batteries We do not recommend that you install batteries into the VIA Bravo MRI unit. The strong magnetic fields near MRI equipment can cause problems if batteries are installed. As stated earlier, we have had some success with using the new NiMH batteries within 8 feet off to the side of a 3t magnet, but have not studied the long term effects of doing this.

  • Page 26: Appendices

    9 Appendices 9.1 VIA Bravo MRI Specifications 9.1.1 Output Characteristics 9.1.1.1 Frequency Range From 100 KHz to 70MHz 9.1.1.2 Sweep Width Min: Less than +/- 1.0% of center frequency Max: 25.6MHz or 32 MHz (for 80 or 100 point graphs) 9.1.1.3...

  • Page 27: Display Characteristics

    9.1.2.3 Accuracy 9.1.2.3.1 Impedance The accuracy varies as a function of the load. +/- 1 ohm at 10 ohm load +/- 1.5 ohms at 50 ohm load +/- 4 ohm at 100 ohm load +/- 35 ohms at 500 ohm load Indication only above 500 ohms load 9.1.2.3.2 Phase +/- 5 degrees...

  • Page 28: Absolute Maximum Ratings

    Data type 8 bit, no parity, and 1 stop bit, with XON/XOFF handshake 9.1.4.2.3 Connector Type Serial input is a 1/8 inch stereo jack. Tip = RD (from VIA Bravo MRI to PC), Ring = TD (from PC to VIA Bravo MRI), Common=ground 9.1.4.3...

  • Page 29: Size

    9.1.5.2 DC Input (Power Jack) + 20VDC Maximum 9.1.5.3 Serial Port Input Max applied voltage on Ring (TD) +/- 20 VDC Max applied voltage on Tip (RD) +/- 10 VDC 9.1.6 Size 8.5 x 4.3 x 2.25 inches (235 x 110 x 57mm) 1.9 lbs (800grams) with batteries and beltcase...

  • Page 30: Menu Chart

    9.2 Menu Chart 9.2.1 Function Key Operations Function Key 1st level menu 2nd level menu 3rd level menu F1 Help Page Off, 10, 20, 50 sweeps, Backlight or continuous, plus 16 Time/Intensity brightness levels Display Contrast 16 levels Unit Properties 4 volume levels plus 3 Audio Options modes: on, off, readout...

  • Page 31: Non Function Key Operations

    Some commands do not require the EOS marker. The VIA Bravo MRI unit sends an EOS marker in response to a command. If the VIA Bravo MRI doesn’t understand the command, no EOS response occurs. The ASCII char ‘*’...
  • Page 32 SWR and return loss Reflection coefficient magnitude and angle For fastest throughput, set the unit into R-X mode (D101) and perform calculations to other formats in the Terminal software. The contents of save memory locations can be loaded into the terminal. All save memory locations contain the instrument settings of the VIA Bravo MRI unit, while only some of the locations contain saved data.
  • Page 33 The information sent in the header is shown in the first column of the table. The header and data are sent in one continuous string, but they are divided up in the tables for clarity. The numbers sent will always be integers (0 to very large) and do not contain decimal points or commas.

  • Page 34: Unit Setup

    9.3.1.2.3 Memory Read Response (Mxx) Sends the data stored in memory location xx. The EEPROM memory location contains the unit setup info, and sometimes has plot data from a single sweep saved by the user. The response from the unit is shown in the table below.

  • Page 35: Unit Setup Commands

    9.3.3 Unit Setup commands 9.3.3.1.1 Fx..x Set the center frequency, x..x is the center frequency in Hz. Range of center frequencies depends on version of unit, limits can be determined from unit setup data. No EOS marker is required if immediately followed with another command, but one may be sent if desired.
  • Page 36 no effect on the unit’s setup. These read only values will be sent to the terminal in response to a S000 or Mxx command. Setup Data Table Characters Range of x…x Meaning Notes Received Toss this out S002 Header denotes unit setup info follows Fx…x 100,000 to...
  • Page 37 See left above Ax…x 0 to 8 Right plot type Ax…x 0 to 1 X axis Label 0=+/- dF; 1= +/- F Ax…x 0 to 1 Reserved cable Z Ax…x 0 to 2,000 , characteristic Z Ax…x 0 to 1000 1000x Velocity factor Cable Vf Freq up/down key...

  • Page 38: Examples

    M01S001F200000W4000A0…A7 Read Save memory 1, Freq=200K, 0000* Width=4KHz, Instrument mode = VIA; … Max center freq=70MHz S000 S002F500000W32000A1…A700 VIA Bravo MRI’s current settings: Freq=500K, Width=32KHz, Instrument mode = SWR, … Max center freq=70MHz F5000000* Center freq = 5MHz W800000* Sweep width = 800KHz...

  • Page 39: Ascii Table

    9.4 ASCII Table Null Space " & XOFF < > Characters 0 to 31 are not used by VIA Bravo MRI except for XON/XOFF Lower case letters are not used by VIA Bravo MRI...

  • Page 40: Coaxial Cable Reference Table

    10 Coaxial Cable Reference Table Coax Part # Characteristic Z Velocity factor (%) 10base2 9907 10base5 9880 FSJ150A FSJ1-75 FSJ4-50B FSJ4-75A FT4-50 HJ4-50 HT4-50 HJ4.5-50 HJ5-50 HT5-50 HJ5-75 HJ7-50 HJ8-50 HJ9-50 HJ11-50 HJ12-50 LDF2-50 LDF4-50 LDF4-75 RG-6/U 9116 RG-6A/U 8215 RG-8/U 8214 RG-8/U 8237 RG-8/U 9913...
  • Page 41 RG-62A/U 9269 RG-58B/U 825 RG-63 9857 RG-71 9169 RG-122/U 9252 RG-141A/U RG-142 RG-142B/U RG-174/U 8216 RG-178B/U RG-179 83264 RG-180 83266 RG-187A/U RG-188A/U RG-212/U 9861 RG-213/U 8267 RG-214/U 8268 RG-216 9850 RG-223/U 9273 RG-303 84303 RG-316 84316 RG-316/U 83284 RG-402/U 1673A RG-405/U 1671A...
  • Page 42 NOTES:...
  • Page 43 NOTES:...
  • Page 44 5933 Sea Lion Place Suite 112 5933 Sea Lion Place Suite 112 Carlsbad CA 92010 Tel: 800 Tel: 800-258-7805 or +1-760-931-8979 Fax: +1-760-931-8969 www.aeatechnology.com...

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