Frequently
Asked Questions
3. The HP 8530A displays the message "CAUTION: NO IF FOUND" or "CAUTION: PHASE-LOCK LOST". 4. The HP 8530A displays the message "CAUTION: IF OVERLOAD". 5. The program stops during receiver initialization. 7. The receiver is not responding to NSI software commands. 8. HP 8530A powers up with following message: "FAILED PRETUNE". 1. There are two GPIB connectors on the back panel of my HP 8530A receiver. Should they be connected together? No, the two GPIB connectors should never be connected together. The port labeled 'HP-IB' should be connected to the computer's GP-IB card. The port labeled 'System Interconnect' should be connected to the RF and LO source when used in analyzer mode with the HP 8530A controlling the sources (see NSI 85301B user's manual). When the NSI measurement workstation controls the sources (for multiple frequency measurements), both RF and LO source GPIB cables should be connected to the computer's GP-IB card (see NSI 85301B user's manual). 2. Why does the HP 8530A display report "SYSTEM BUS ADDRESS ERROR" when powering up or during some operations? In NSI 85301B systems, the sources are not controlled by the HP 8530A unit on the 'System Interconnect' bus but are controlled by the NSI workstation controller on the main GPIB bus. The NSI software configures the HP 8530A unit to ignore the control of the sources by setting their addresses to 31 (inactive) but the HP 8530 still checks for the sources and reports an error during some operations. This error message will not affect the system operation or accuracy and may be safely ignored. 3. The HP 8530A displays the message "CAUTION: NO IF FOUND" or "CAUTION: PHASE-LOCK LOST". NO IF FOUND or PHASE LOCK LOST is usually caused by inadequate power at the reference input of the HP 8530A (a1 is usually the reference input). Verify that the appropriate power levels are available using NSI V3.5 menu option <M07444> or from HP 8530A front panel press Parameter <menu><service parameters><Service1 a1>. The signal level should be between -45 and -10 dBm. Also, make sure the system is set to a frequency range valid for the cables and other components involved. If you are using an HP 8511 frequency converter, make sure the coupled port of the directional coupler is connected to the input port 'a1' and the analyzer is set for parameter 'S21'. If you are using an HP 85309A, make sure the IF jumper is installed on rear panel connectors J7 and J8. Ensure the source is turned on and is putting out the appropriate power levels. 4. The HP 8530A displays the message "CAUTION: IF OVERLOAD". IF OVERLOAD indicates that the reference (or test) channel IF signal exceeds the -10 dBm maximum input signal level. Use a higher value directional coupler or add attenuation to the reference line to pad the reference signal down sufficiently. Use attenuation in the test path if needed to pad the test signal down sufficiently. NOTE: make sure the probe is positioned at the point of maximum signal strength.
The program load sequence 'hangs' while initializing the HP 8510B/C or HP 8530A receiver. No changes are observed on the computer display or network analyzer display. The program is unsuccessful in its attempt to talk to the network analyzer on the GPIB bus. Verify that the HP 8530A HPIB port is connected to the National Instruments GPIB-PCII card in the computer. Verify the GPIB address of the HP 8530A is set to '16'. Check configuration menu <M0770> to verify the frequency output is set to 'GPIB interface' and the address is set to 16. To check the GPIB card, remove the card from the computer and verify the hardware address DIP switches on the GPIB-PCII card in the computer are set to (Hex 2B8). Ensure that the jumpers are on the following pins: IRQ7, DRQ1, DACK1 and C2.
If the analyzer is an HP 8510C/B or HP 8530A, measurements are made using the external TTL trigger, and the trigger is not working properly. Check the connection of the 'Trigger In' or 'Event Trigger' BNC input on the rear panel of the network analyzer or receiver. Verify that the trigger cable is connected to one of the following computer output ports: a. J11, Receiver Trigger, BNC output on rear panel of DSP Interface Unit (NSI-OP-5905C/E) b. J9, TTL Trigger, BNC output on rear panel of Antenna Range Controller (ARC box, NSI-SC-5911). 7. The receiver is not responding to NSI software commands. The receiver may be in an unknown state and is not responding to communication attempts by the NSI program. Use <M0745> to reset the receiver. If there is no response, use the 'Preset' key on HP 8510B/C or HP 8530A front panel (after setting it to local control) to place the receiver in a known state. If the receiver is still not responding, power off the top unit (HP 85101C display unit) then power it back on. If the receiver is still not responding check the GPIB interface (see FAQ #4). 8. HP 8530A powers up with following message: "FAILED PRETUNE". This error is caused by a failure of the HP 8530A to phaselock for systems using a synthesized LO. On the HP 8530A front panel, press <System><Phaselock><None>. 9. The front panel 'LO Power Out of Range' LED on the HP 85309A front panel is 'on' during multiple frequency scanning. The detector voltage display is also changing. Is there a problem with LO power levels? During multiple frequency operation, the LO source power is changing, similar to low power level during sweep retrace. Check to see that a 50 ohm BNC cable is connected from the LO source 'Pos Z Blank' output connector to the HP 85309A 'Pos Z Blank' input connector. The LO source (HP 83621B for example) sends out the POS Z BLANK (TTL logic) signal during sweep retrace. POS Z BLANK is monitored by 85309A and lowers the gain in ALC during retrace. This keeps gain of the ALC from peaking during known power drops. If the cable is missing, the system will still operate properly, since the measurement is taken only after both sources have settled. 10. I'm using an 8530A receiver and I keep getting the 'HP Stop Sweep Line Low' fault while scanning. This could be caused by one of two different problems:
A. The calculated receiver measurement time is incorrect. The following test will help to isolate the problem. 1. Setup the 8530 receiver for 1 average (310 usec) and make sure the receiver settling time is set to 200 usec. These dwell times are "factory default settings" and are known to work.If the HP Stop Sweep Line low fault occurs, then it is either a hardware problem with the receiver, or there is a internal setting in the receiver that the NSI software is not overwriting. Check all trigger and stop sweep BNC cables and connections. If there is no Stop Sweep fault, then the problem is most likely an overlap of the beam sets. Try a larger value for the parameter Measurement_Safety_Margin defined in c:\NSI 2000\startup.srt. Do not change the value of the receiver settling time as a work around. Doing so will create a bi-directional error in the scan data. 11. I have purchased a new RF cable with SMA connectors, but I have been unable to connect it to my WR-22 probe. You may need an adapter. The WR-22 probe (33 to 50 GHz) uses 2.4mm(f) connectors, which are not compatible with the SMA(m) connectors on your cable. The 2.4mm connectors are designed for operation to 50 GHz and have a different mechanical configuration to prevent mating with the lower frequency SMA and 2.9mm connectors. If you wish to operate the system in the frequency band of your WR-22 probe, you will need to purchase a higher frequency cable with 2.4mm(m) connectors. A 40 GHz cable could also be used with 2.9mm(m) connectors for operation between 33 and 40 GHz, and you would also need a 2.9mm(f) to 2.4mm(m) probe adapter. 12. Agilent 8360 Synthesizer specs say switching time is 5 ms + 5 ms per GHz step size, but increases to maximum of 50 ms across band switch points. Where are the band switch points? Frequency band switch points for the 8360 Series Synthesizers
are shown in the following table. Note that for dual source
systems the LO source may cross band points during harmonic
mixing while the RF source steps within a band. As an
example, during third harmonic mixing the 83631B RF source would
step within band from 20 GHz to 21 GHz, while the 83621B
LO source steps from 6.666 GHz to 7 GHz in next band.
The total switching time for this step, therefore, would be
a maximum of 50 ms.
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