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AEA Technology, Inc. Bravo MRI II Скачать руководство пользователя страница 16

12

3.12

Cable Nulling using the included terminators

Any load connected to a coax that is not perfectly matched to the coaxial cable’s

characteristic impedance will have its impedance modified by the coax. Cable nulling allows
you to remove the effect of the coaxial cable so that the impedance you read shows the
impedance of the load at the end of the cable, without the cable modifying effects.

Cable nulling is selected by using one of the (with cable) options when selecting the

instrument mode. The Bravo MRI II will prompt you for the required action during the cable
nulling procedure. Basically, the Bravo MRI II takes three readings: open circuit, short circuit,
and nominal Z

0

.

The data that results from a procedure that nulls a cable will be specific for that cable. If

the cable is changed, a new nulling must be performed. If the power is turned off, the cable
nulling information will be lost, so a new cable nulling procedure will be required after power
is restored. Note, if you power-up again and do not wish to use cable nulling, you can just
fake it by going though the nulling procedure without any cable or load, then change the
instrument state to “no cable”.

3.12.1

Cable Definition

The coaxial cable characteristic impedance must be defined for cable nulling to operate

properly. This can be done in the Cable Characteristics sub menu (see 3.11.4 ).

3.12.2

Nulling Procedure

The nulling procedure begins by selecting a <with cable> option when setting up the

instrument mode (see Error! Reference source not found.or Error! Reference source not
found.). Install the cable to be nulled to the RF connector of the Bravo MRI II unit. Once the
instrument mode is selected and the cable is connected, the procedure can begin using the
included terminators.

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 Bravo MRI II 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 coaxial short, press the ENTER key once.

When this step is complete the display shows that it wants the nominal impedance
termination, usually 50 (or 75) ohms.

3.12.2.3

Nominal Z Reading

With the far end of the coax terminated with a matched load (50 Ohms is included in the

kit), press ENTER once. The firmware will compute and apply the corrections. This
completes the cable nulling procedure. To verify that you completed the procedure correctly,
notice that the display shows flat line(s) at Z

0

(and near zero degrees). If that procedure went

well, remove the matched load. Now you are ready to take measurements at the end of the
coax. If you do not see flat lines at the expected values, redo the procedure starting at
3.12.2.

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Содержание Bravo MRI II

Страница 1: ...Dual Port Vector Impedance Analyzer rt Vector Impedance Analyzer 100KHz to 200 MHz...

Страница 2: ...ntenance is prohibited without written authorization from AEA Technology Inc All rights reserved 2014 by AEA Technology Inc All rights reserved This document and all software or firmware designed by A...

Страница 3: ...o Options 6 3 8 4 Cable Nulling 7 3 9 F3 PLOT DATA PROPERTIES 7 3 9 1 Left Plot Type 1 st Plot 7 3 9 2 Right Plot Data 8 3 9 3 RLC Model Series Parallel 9 3 9 4 Plot Width 9 3 9 5 Big Frequency Displa...

Страница 4: ...19 8 1 CONTRAST 19 8 1 1 Environment and Contrast 19 8 1 2 Power on Preset Value if Contrast Was Lost 19 8 1 3 Power Induced Failure 20 8 2 BATTERIES 20 8 3 SERIAL PORT 20 8 4 OTHER PROBLEMS 20 9 APPE...

Страница 5: ...s 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 Br...

Страница 6: ...tions the sweep widths must be certain values and the Bravo MRI II adjusts your entry to an available sweep width The Bravo MRI II flashes a brief warning if it changes the sweep width from the number...

Страница 7: ...rst digit of your desired center frequency The frequency entry screen pops up Finish entering the center frequency Note that you may need to add zeroes to get your entry to align properly with the dec...

Страница 8: ...o enter digits until an illegal width too wide is entered When you press the ENTER key the display resets allowing you to start a new sweep entry 3 3 Frequency Step Size The frequency step size determ...

Страница 9: ...ion cycle One way to do this is to just enter a new center frequency para 3 1 Other ways to force a calibration cycle are to press the FREQ or WIDTH keys while in the plot mode para 3 1or 3 2 EXAMPLE...

Страница 10: ...ome on again for another 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 Bravo MRI II is in a...

Страница 11: ...he Q of the SWR curve in SWR operation 3 9 1 Left Plot Type 1st Plot This sub menu allows you to choose which data to plot on the left axis with the non hashed curve The data types depend on the instr...

Страница 12: ...1 1 9 No Plot self explanatory 3 9 1 2 S21 Operation 3 9 1 2 1 Linear Gain The returning signal into the S21 Port is measured in relation to the signal going out on the S11 port expressed in linear u...

Страница 13: ...wever the 100 point display leaves no room for large numeric displays so all center frequency values are displayed with small digits Pick the plot width you are most comfortable with 3 9 5 Big Frequen...

Страница 14: ...1 1 2 Plot Data Memory locations 17 to 24 save both plot data and instrument presets 3 11 2 Recall Operation Memory recall is the compliment to memory save When memory locations 17 to 24 are recalled...

Страница 15: ...use in this sub menu The data format is always N 8 1 with XON XOFF handshaking 3 11 6 Self Test You can perform a self test by selecting this choice Press ENTER to quit the self test Pressing any othe...

Страница 16: ...g to operate properly This can be done in the Cable Characteristics sub menu see 3 11 4 3 12 2 Nulling Procedure The nulling procedure begins by selecting a with cable option when setting up the instr...

Страница 17: ...The Bravo MRI II compliments the plot displays with a number of numerical quantities These quantities depend on the sweep settings and the instrument mode 3 12 5 80 Point Sweeps The 80 point sweeps u...

Страница 18: ...zero phase crossing from lower left to upper right Impedance will be very low This method is less preferred as the coax must be re shorted after every snip 4 2 Make a wavelength coaxial line To make...

Страница 19: ...y of interest The length in degrees is L 180 number of zero crossings modified RCA Calculate the modified RCA using this algorithm if the RCA is positive then subtract off 360 from RCA if RCA is negat...

Страница 20: ...as provided on your CD package and hit ENTER This is CASE SENSITIVE so be sure to type it in exactly as listed on your documentation The upper left corner of the title box should now say Registered to...

Страница 21: ...ternal DC Power If you wish to power the Bravo MRI II from an external DC source other than the AEA AC 1 ensure that it meets the requirements of 9 1 4 3 1 6 3 Batteries For optimal performance in the...

Страница 22: ...l 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...

Страница 23: ...on condition 8 1 3 Unit gives bad readings Cable nulling function is in wrong state 3 12 8 1 Contrast 8 1 1 Environment and Contrast Occasionally changes in temperature or ambient light conditions ma...

Страница 24: ...after 5 seconds If you are using battery power unplug the power pack from the Bravo MRI II unit The faint blue rectangle should be gone After the power has been removed for 5 seconds you may press the...

Страница 25: ...00am 4 00pm Pacific Time or by email at techsupport aeatechnology com Return Material Authorization RMA Number If after contacting AEA Technology s Technical Support it is determined your instrument n...

Страница 26: ...lution Less than 0 02 of center frequency 9 1 1 4 Output level 5 dBm typical 9 1 1 5 RF Connector Dual N type receptacles BNC type receptacles optional 9 1 1 6 Output Impedance 50 ohms nominal VSWR ty...

Страница 27: ...75MHz Indication only above 500 ohms load freq 75MHz Indication only above 300 ohms load freq 75MHz 9 1 2 3 2 Phase 5 degrees below 50MHz frequency MHz 10 above 50MHz 9 1 2 4 Spectrum Analyzer This sp...

Страница 28: ...sweeps per second In CW mode several updates per second 9 1 4 Miscellaneous Specifications 9 1 4 1 Non Volatile Memory 24 total user definable memory slots Slots 1 to 16 store instrument preset values...

Страница 29: ...performance is impaired when input is below 12VDC Positive polarity is applied to the center pin of the power jack for proper operation 9 1 5 Battery Power choice of 8 AA Alkaline 8 AA NiMH 8 AA NiCad...

Страница 30: ...1A or G P L or First Plot S11 or S21 none Z A R X SWR RL S11 S11A or G P L or F3 Second Plot S11 or S21 none Axis Selection RLC Model Series or parallel Plot Width 80 or 100 points Big Freq Display On...

Страница 31: ...2600 Self Test Self rest results and keypad tester 9 2 2 Non Function Key Operations First Action Final Action Result Enter New center frequency Numeric entry Freq up New step size and center frequenc...

Страница 32: ...l program running on a PC The controller unit that communicates with the Bravo MRI II unit will be referred to as the Terminal throughout this document 9 3 1 Data Requests The data requests are short...

Страница 33: ...instrument presets no data Locations 17 to 24 presets and plot data This command requires no EOS marker but one may be sent if desired 9 3 1 1 5 S000 Read the unit s current setup The entire setup is...

Страница 34: ...s Rx xXy y 0 to 32 767 32 768 to 32 767 R 10x ohms X 10x j ohms insert Before last digit Resist React D 101 Zx xAy y 0 to 32 767 899 to 899 Z 10x ohms A 10x degrees insert Before last digit Total Z Z...

Страница 35: ...data lower and upper valid data indices Data that is not valid is garbage and should be tossed out Memory Read Response Table Characters Received Range of x x Meaning Notes Mxx 1 to Memmax Header allo...

Страница 36: ...the unit s configuration An entire block of configuration data follows this command The format of this data block is identical to the unit response for configuration request without the S002 No EOS m...

Страница 37: ...qual to 0 except when the sweep would try to extend below the minimum freq Ax x 40 to 100 Upper plot index Usually the same as points in a sweep except when sweep extends beyond maximum freq Ax x 0 to...

Страница 38: ...Size KHz Freq up down key Ax x 100 to 50 000 Min width KHz in 100MHz octave Ax x 10 000 to 200 000 Max width KHz in 100MHz octave Ax x 1 to 1000 Min center freq KHz Ax x 1000 to 200 000 Max center fre...

Страница 39: ...00 Read Save memory 1 Freq 200K Width 4KHz Instrument mode VIA Memory slots 24 Max center freq 50MHz S000 S002F500000W32000A1A5 A2 00000 Bravo MRI II s current settings Freq 500K Width 32KHz Instrumen...

Страница 40: ...M 109 m 14 46 78 N 110 n 15 47 79 O 111 o 16 48 0 80 P 112 p 17 XOFF 49 1 81 Q 113 q 18 50 2 82 R 114 r 19 XON 51 3 83 S 115 s 20 52 4 84 T 116 t 21 53 5 85 U 117 u 22 54 6 86 V 118 v 23 55 7 87 W 11...

Страница 41: ...52 92 HJ8 50 52 93 HJ9 50 52 93 HJ11 50 52 92 HJ12 50 52 93 LDF2 50 52 88 LDF4 50 52 88 LDF4 75 73 88 RG 6 U 9116 73 82 RG 6A U 8215 73 78 RG 8 U 8214 52 78 RG 8 U 8237 52 66 RG 8 U 9913 52 84 RG 8 U...

Страница 42: ...142 52 70 RG 142B U 52 70 RG 174 U 8216 52 66 RG 178B U 52 70 RG 179 83264 73 70 RG 180 83266 93 70 RG 187A U 73 70 RG 188A U 52 70 RG 212 U 9861 52 66 RG 213 U 8267 52 66 RG 214 U 8268 52 66 RG 216...

Страница 43: ...Noise Filter Be aware that the filter will smooth almost any curve and may alter good data A perfectly good Return Loss plot has a very sharp point at the bottom without the filter on Applying the fi...

Страница 44: ...Notes...

Страница 45: ...Tel 800 5933 Sea Lion Place Suite 112 Carlsbad CA 92010 Tel 800 258 7805 or 1 760 931 8979 Fax 1 760 931 8969 www aeatechnology com...

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