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What safety precautions regarding high voltage should be observed when operating the IFR A-7550 Spectrum Analyzer?
The IFR A-7550 contains certain circuits and/or components of extremely high voltage potentials, capable of causing serious bodily injury or death. When performing any procedures, heed all applicable safety precautions.
Rescue of Shock Victims:
1. Do not attempt to pull or grab the victim.
2. If possible, turn off the electrical power.
3. If you cannot turn off electrical power, push, pull or lift the victim to safety using a wooden pole, a rope or some other dry insulating material.
First Aid:
1. As soon as victim is free of contact with source of electrical shock, move victim a short distance away from shock hazard.
2. Send for doctor and/or ambulance.
3. Keep victim warm, quiet and flat on his/her back.
4. If breathing has stopped, administer artificial resuscitation. Stop all serious bleeding.
How should I handle the IFR A-7550 Spectrum Analyzer to prevent electrostatic discharge damage?
Integrated circuits and solid state devices such as MOS FET’s, especially CMOS types, are susceptible to damage by electrostatic discharges received from improper handling, the use of ungrounded tools, and improper storage and packaging. Perform maintenance with the following precautions:
1. Before using in a circuit, keep all leads shorted together either by the use of vendor-supplied shorting springs or by inserting leads into a conductive material.
2. When removing devices from their containers, ground the hand being used with a conductive wristband.
3. Tips of soldering irons and/or any tools used must be grounded.
4. Devices must never be inserted into nor removed from circuits with power on.
5. PC Board, when taken out of the set, must be laid on a grounded conductive mat or stored in a conductive storage bag.
6. PC Boards, if being shipped to the factory for repair, must be packaged in a conductive bag and placed in a well-cushioned shipping box.
What are the power input and operating precautions for the IFR A-7550 Spectrum Analyzer?
To prevent possible damage to the IFR A-7550, observe the following:
Analyzer Input Connector: Maximum input into this connector must not exceed 4 VDC, +30 dBm for Input Attenuator setting of 60 dB, and +20 dBm for all other attenuator settings. Signals exceeding the maximum input level can cause damage to the unit.
Generate Output Connector: This connector is used when Tracking Generator Option (02) is installed. Do not apply input through this connector.
Intensity: Do not operate CRT display with excessive intensity.
PWR/OFF/BATT Switch: To provide maximum protection of non-volatile memory contents, allow a minimum of 5 seconds between selection of “PWR” and “OFF” positions. Do not rapidly cycle power on and off. Ensure electrical power is not removed from the IFR A-7550 during data entry before the ENTER Key is pressed, as the data being entered will be lost.
Do not apply any signals into the IFR A-7550 other than those defined in the operating instructions.
How do I prepare the IFR A-7550 Spectrum Analyzer for use with different power sources?
External AC Power:
1. The IFR A-7550 operates from 106 to 266 VAC, 50 to 400 Hz.
2. Connect furnished AC power cable between 106 to 266 VAC power source and AC Power Input connector on rear panel of A-7550.
3. Set PWR/OFF/BATT switch to “PWR”.
External DC Power:
1. The IFR A-7550 operates from 12-30 VDC. Do not start a vehicle with the A-7550 plugged into the electrical system.
2. Connect furnished DC power cable between external 12-30 VDC power source and DC Power Input Connector on rear panel of A-7550.
3. Set PWR/OFF/BATT switch to “PWR”.
Internal Battery Power (Optional):
1. The internal battery can furnish up to 30 minutes of remote operation where external AC or DC is not available.
2. Press PWR/OFF/BATT Switch to “BATT”.
3. An internal timer circuit shuts off battery power after approximately 10 minutes of operation. The PWR/OFF/BATT Switch may be set to “BATT” again for further operation.
How do I clear the IFR Logo display upon power-up of the IFR A-7550 Spectrum Analyzer?
Whenever the IFR A-7550 is first powered up, the IFR logo should appear on the CRT display. After a short period of time following power-up, the logo is automatically cleared from the display. Pressing any button on the keyboard can also be used to clear the display. The analyzer is then ready for operation.
What are the functions of the front panel connectors on the IFR A-7550 Spectrum Analyzer?
GENERATE OUTPUT Connector (7): Output connector used for Tracking Generator output if this option is installed. Impedance is normally 50 ohms, but may be manually set to 75 ohms if the optional adapter is installed. To operate at 75 ohms, the SETUP menu should be changed for proper amplitude readings on the CRT.
TRACKING Adjust (8): Adjusts frequency of Tracking Generator to match the Analyzer, if this option is installed. Adjust for peak signal using 300 Hz Bandwidth and GENERATE OUTPUT (7) connected to ANALYZER INPUT (10).
CAL OUT Connector (9): Provides a 100 MHz signal at -30 dBm to check accuracy of A-7550. CAL OUT Connector must be connected to ANALYZER INPUT Connector with a coax cable for this check.
ANALYZER INPUT Connector (10): Input connector for signal of interest. Input impedance is normally 50 ohms, but may be set to 75 ohms. Impedance is manually set to 75 ohms with optional adapter and by changing SETUP menu.
EXT AMP Connector (6): Used for the +20 dB External Amplifier Option 03.
How are values entered using the keyboard on the IFR A-7550 Spectrum Analyzer?
| KEY | USE | ENTRY METHOD |
|---|---|---|
| RF ATTEN | RF Input atten from 0 to 60 dB in 10 dB steps | RF ATTEN up or RF ATTEN down |
| IF GAIN | Internal IF gain from 0 to 65 dB in 1 dB steps | IF GAIN up or IF GAIN down |
| SCAN WIDTH | Analyzer Display dispersion from 1 kHz/DIV to 100 MHz/DIV; 0 for fixed-tuned receiver | SCAN WIDTH up or SCAN WIDTH down |
| SWEEP RATE | Analyzer Display sweep rate from 5 mSec/DIV to 2 SEC/DIV | SWEEP RATE up or SWEEP RATE down |
| RES BW | Analyzer Bandwidth – 300 Hz, 3 kHz, 30 kHz, 300 kHz or 3 MHz | Press RES BW |
| 2 dB/10 dB/LIN | Log – 10 dB or 2 dB per division on vertical scale. Lin – selects Linear display mode | Press 2 dB/10 dB/LIN |
| RF | Direct center frequency change from 000.0050 to 999.9999 MHz | RF 999.9999 ENTER* |
| MENU | Calls up menus | Press MENU |
| FREQUENCY | Center frequency slewing | Press any of 6 FREQUENCY keys |
| GEN | RF output atten from 0 to -75 dBm in 1 dB steps | GEN up or GEN down |
| NUMBER Keys | Center frequency entry and menu ops | Redefined by RF and MENU |
| ENTER | Direct center frequency entry | RF 999.9999 ENTER* |
*Values entered for RF entries can contain one to seven digits. The maximum length on either side of the decimal point is shown here. The decimal is optional for integer values (0-999). Entering an invalid value suppresses the beep tone.
How do I access and navigate the menus on the IFR A-7550 Spectrum Analyzer?
IFR A-7550 operating parameters are set using direct entries from the keyboard or via menu operation. Enter menu operation by pressing “MENU” on the keyboard. Menus can be subsequently cleared from the CRT display by pressing “MENU” a second time or by pressing “Ø” on the keyboard when the “Master” menu is displayed in the menu “window”.
The Master Menu is the only first level menu. It is used to select a second level menu (DISP, MODE, RCVR, FILTERS, SETUP and PLOT). Select a second level menu by pressing the NUMBERED KEY corresponding with the number listed in the menu window left of the desired menu.
Return to the previous menu level by pressing Ø (RETURN) on the keyboard. Pressing the MENU Key twice in succession during menu operation causes the Master Menu to appear in the menu window.
How do I use the DISPLAY (DISP) Menu on the IFR A-7550 Spectrum Analyzer?
To select the Display (DISP) Menu, press “1” on the keyboard when the Master Menu appears in the menu window. The available options are:
1 LINE: Causes the Analyzer Trace to be represented as a solid line.
2 BAR: Causes the Analyzer Trace to be represented as a shaded area.
3 REF: Display shows a signal display which represents the difference between a live trace and a stored trace.
To return to the Master Menu, press “Ø” on the keyboard.
What are the display modes available in the MODE Menu of the IFR A-7550 Spectrum Analyzer?
To select the MODE Menu, press “2” on the keyboard when the Master Menu appears.
1 AVE (Average): The last three sweeps are averaged with the current sweep (i.e., four sweeps), which are continuously updated to reflect the average.
2 COMP (Compare): The trace stored in memory is compared to and displayed with the current (live) trace. The shaded area is the difference between the live and stored traces. Selecting COMP automatically sets the DISPLAY Menu to BAR.
3 STORE: The current trace and display parameters are stored.
4 RECALL: The stored trace, with its parameters, are recalled and displayed on the CRT. Changing any parameter after selecting RECALL results in the A-7550 switching to LIVE Mode.
5 LIVE: This is the normal mode of operation.
6 PKHOLD (Peak Hold): Continually stores and displays maximum signal amplitude. The difference between the current signal and the maximum signal is displayed as a shaded area.
How do I configure the Setup Menu options on the IFR A-7550 Spectrum Analyzer?
To select the SETUP Menu, press “5” on the keyboard when the Master Menu appears.
1 (50 ohm / 75 ohm): Selects 50 ohm or 75 ohm operation. Note: Changing this setting does not change the physical impedance! A 50 to 75 ohm adapter must be connected to the ANALYZER INPUT Connector.
2 (Units): Resets the graticule unit. Selectable units are dBm, dBmV, dBuV, dBV, or dBuW. The current setting is displayed in the menu window.
3 Remote: Selects the REMOTE operating mode (GPIB or RS-232 if installed).
4 Manual: Selects the MANUAL Menu to control Bandwidth Optimization, Sweep Rate Optimization, and Auto Cal.
5 Test: Selects the TEST Menu to run self-tests (RAM, ROM, Cal, RF, Bat).
6 Gen (Tracking Generator): Sets the Tracking Generator ON (Gen = 1) or OFF (Gen = 0). When ON, the output level can be adjusted using GEN UP/DOWN keys.
How do I initiate a plot using the PLOT Menu on the IFR A-7550 Spectrum Analyzer?
Use of the Plotter requires GPIB installation. Attach a GPIB cable between the GPIB Connector on the Rear Panel of the A-7550 and the GPIB Connector of any HP-GL compatible plotter. Set the plotter to LISTEN ONLY mode.
To select the PLOT Menu, press “6” on the keyboard when the Master Menu appears.
1: Draw the grid on the plotter (represents all graticules and tick markings).
2: Draw labels and parameter values of the stored trace.
3: Draw the stored trace on the plotter.
4: Stop any of the above functions before completion.
5 (Auto): Performs the functions of selections 1, 2 and 3 without interruption.
What are the remote operation commands for the IFR A-7550 Spectrum Analyzer?
The following commands are used for both GPIB and RS-232 remote operation:
| COMMAND | RANGE | DEFINITION |
|---|---|---|
| ACAL | —- | Forces one AutoCal cycle, if AutoCal enabled. |
| ACAL= | 0,1 | Disables (0) or Enables (1) Auto Cal feature. |
| ACAL? | (0,1) | Returns A Cal status (Enabled or Disabled). |
| BATT? | (11.0 to 15.0 V) | Returns Battery voltage. |
| BW= | .3, 3, 30, 300, 3000 kHz | Set Resolution B/W. |
| BW? | (.3, 3, 30, 300, 3000 kHz) | Get Resolution B/W. |
| BWC= | A or M | Disable (M) or Enable (A) B/W optimization. |
| BWC? | (A or M) | Returns B/W optimization status. |
| DEL= | 0 to 127 | Sets the delimiter to the ASCII character represented by the assigned decimal number. |
| DEL? | (0 to 127) | Returns the decimal number for the ASCII delimiter character. |
| DISP= | LINE, BAR, REF | Sets display to one of three modes. |
| DISP? | (LINE, BAR, REF) | Returns display mode of A-7550. |
| GEN= | 1, 0 | Set the generator on (1) or off (0). |
| GEN? | (1, 0) | Return status of Gen Switch. |
| GENLVL= | 0 to 70 | Set generator output level. Depends upon “REF=” and “IMPD=” Command settings. |
| GENLVL? | (0 to 70) | Return generator output level setting. |
| GET(xx)? | (0-511) | Returns 10 points out of the 390 stored points from the last stored display beginning with data group xx (1-39). |
| IFGAIN= | 0 to 65, step 1 dB | Set the IF GAIN to the designated value. |
| IFGAIN? | (0 to 65) | Get the IF GAIN value. |
| IMPD= | 50, 75 | Set the impedance (in ohms). |
| IMPD? | (50, 75) | Get the impedance value. |
| MIN? | (0-511:1-390) | Returns the minimum value of the last stored display for the specified horizontal range. |
| MODE= | AVE, COMP, STORE, RECALL, LIVE, PKHOLD | Sets A-7550 to selected mode. |
| MODE? | (AVE, COMP, STORE, RECALL, LIVE, PKHOLD) | Returns A-7550 mode. |
| PEAK? | (0-511:1-390) | Returns the peak value of the last stored display for the specified horizontal range. |
| PEAKF= | NONE, 30K, 300 | Set peak filter value. |
| PEAKF? | (NONE, 30K, 300) | Get peak filter value. |
| PUT(xx)= | 0-511 | Sends 10 points to the A-7550 to be stored for display beginning with data group xx (1-39). |
| QUASI= | TC1, TC2, TC3 | Set Quasi-Peak filter value. |
| QUASI? | (TC1, TC2, TC3) | Return Quasi-Peak filter value. |
| RCVR= | FM1, FM2, SSB, AM1, AM2 | Sets 10.7 MHz Receiver Modulation. |
| RCVR? | (FM1, FM2, SSB, AM1, AM2) | Returns 10.7 MHz Receiver Modulation. |
| REF= | DBM, DBUW, DBV, DBMV, or DBUV | Set scale reference label. |
| REF? | (DBM, DBUW, DBV, DBMV, or DBUV) | Return scale reference label. |
| RFATN= | 0 to 60, step 10 dB | Set RF Input Attenuator level. |
| RFATN? | (0 to 60, step 10 dB) | Get RF Input Attenuation level. |
| RFF= | 000.0050 to 999.9999 | Set Analyzer Frequency. |
| RFF? | (000.0050 to 999.9999) | Returns Analyzer Frequency. |
| RID= | ON/OFF | Controls the Reply Identifier Switch. |
| RID? | (ON/OFF) | Returns the current reply identifier status. |
| SCALE= | 2, 10, LIN | Set Amplitude Scale. |
| SCALE? | (2, 10, LIN) | Get Amplitude Scale. |
| SCANW= | 0; .001 to 100 MHz/div in 1-2-5 sequence | Set Frequency scan range. |
| SCANW? | (0; .001 to 100 MHz/div) | Get Frequency scan range. |
| SRQ= | 0X000000 to 1X111111 | Set the GPIB line interrupt mask. |
| SRQ? | (0X000000 to 1X111111) | Returns the current status of SRQ. |
| SWEEPR= | 5 to 2000 MS/DIV in 1-2-5 steps | Set Sweep Rate. |
| SWEEPR? | (5 to 2000 MS/DIV in 1-2-5 steps) | Get Sweep Rate. |
| SWPC= | A or M | Disable (M) or Enable (A) Standard Sweep rate Optimization. |
| SWPC? | (A or M) | Returns Sweep rate Optimization Status. |
| TEST | —- | Runs all A-7550 diagnostics and returns errors. |
| TOP? | (110 to -30) | Returns top of screen scale value. |
| TSR= | 1, 0 | Set Time Share Receiver (TSR) ON (1) or OFF (0). |
| TSR? | (1, 0) | Get Status of Time Share Receiver. |
| VER? | (x.xx) | Returns the current version of the firmware. |
How do I perform a Quasi-Peak measurement on the IFR A-7550 Spectrum Analyzer?
1. Turn on the A-7550 with the UUT turned off. Set it to a Center Frequency of 500 MHz and a Scan Width of 100 MHz/Div (Press “RF” “ENTER”). This allows you to observe the full spectrum of signals.
2. Enter MODE Menu (Press: “MENU” “2”) and select LIVE (Press: “5”). Store the trace (Press: “3”). Exit MODE Menu (Press: “0”).
3. Enter the Display Menu (Press: “1”) and select the REF display (Press: “3”).
4. Turn on the unit to be tested for EMI. Watch for signals which appear when UUT is turned on. Note signals as a comparison to the signal in the previous step.
5. As an example, to look closer at the signal at 100 MHz, press the following key sequence: “MENU” “2” (display mode) “1” (line display) “RF” “100.” “ENTER”.
6. Use the IF GAIN and/or the RF ATTEN keys to position the signal with its peak close to, but not above, the top graticule.
7. Change the Reference Scale to Linear Mode (Press: “2dB/10dB/LIN”) and change the reference units to dBuV (Press: “MENU” “5” {Setup} “2” “2”).
8. Use the SCAN WIDTH DOWN key to set the Scan Width to zero. Return to the Master Menu and select the FILTERS Menu (Press: “0” “4”).
9. Select the Quasi-Peak Filter Menu (Press: “4”). Be sure you have selected the correct Time Constant for the frequency in question.
What is the procedure for verifying the display and basic operation of the IFR A-7550 Spectrum Analyzer?
1. Connect AC Power Cord to AC Power Connector (17) and Plug into electrical outlet.
2. Set PWR/OFF/BATT Switch (2) to “PWR”. Verify Power On Indicator (3) is on and IFR logo appears on the CRT display (11).
3. Wait approximately ten seconds or press any key. The IFR logo should disappear, replaced by the graticule display.
4. If necessary, adjust TRACE Intensity Control (14) and GRATICULE Intensity (13) for desired contrast using a small non-magnetic screwdriver or tuning tool.
5. Press MENU. Verifies Master Menu appears on CRT display.
6. Press 5. Verifies SETUP Menu appears on the CRT display.
7. Press 5. Verifies TEST Menu appears on CRT display and all tests Pass (“P” is indicated in menu window following each test).
8. Press 0. Returns to SETUP Menu.
How do I operate the Tracking Generator on the IFR A-7550 Spectrum Analyzer (if installed)?
1. Press MENU, then 5, then 6. This turns the Tracking Generator ON (GEN = 1).
2. Press GEN ATTEN up or down. This sets the Tracking Generator level. Repeat until tracking level is -35 dBm.
3. Press RF, then 1, 0, 0, ENTER. Sets the Center Frequency to 100.0 MHz.
4. Press RF ATTEN up or down. Sets RF Attenuation to 10 dB.
5. Connect TRACKING GENERATOR (17) to ANALYZER INPUT (20) using a 50 ohm BNC-to-BNC Coax Cable.
6. Press SCAN WIDTH down. Decrease Scan Width until Scan Width is set to 10 kHz/DIV.
7. Press RES B/W. Sets Resolution Bandwidth. Repeat until Resolution Bandwidth is 3 kHz. Verify CRT display is as shown in Figure B-7.
8. Turn Tracking Adjust. Adjusts display for maximum signal amplitude.
9. Press 2dB/10dB/LIN. Sets Graticule Scale to 2 dB/DIV.
10. Press GEN up/down. Decreases Generator Output 1 dB. Repeat until Generator Output level decreases 10 dB. The CRT display should change at each 1 dB step.
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