Hp 8594e Cal res bw ampl fail - Page 1
Forum section: electronics / testgear

author: AwArD_RzD
author_rank: Regular Contributor
timestamp: February 14, 2014, 01:03:46 pm
content: HiI just bought on Ebay an HP 8594e SA (my first SA) , the unit is in excellent exterior condition and it's stated in working condition, but i have some problem with the ampl calibration test and i hope someone here will be enough familiar with this unit to be able to help me.After the unit is on for about an hour i did the confidence test and the frequency cal test and i got no error but when the Ampl cal test run it's stop at the 1Khz BW and say CAL RES BW AMPL FAIL SRQ 110. I checked in the trouble shooting manual and this can be 3 thing, Filter need calibration, a board is fry, or it's just a lack of calibration correction in the memory. In the trouble shooting manual this is the text about thatCAL: RES BW AMPL FAIL (H)During the CAL AMPTD routine, the insertion loss of a resolutionbandwidth filter, relative to the amplitude of the 3 kHz resolutionbandwidth filter, was greater than 2.2 dB.Related AssembliesA7 analog interface, A11 bandwidth filter, A13 bandwidth filter, A14 logamplifier/detector.Troubleshooting HintsThe CAL AMPTD routine will stop at the resolution bandwidth thatfailed. If the A11/A13 bandwidth filter assemblies require realignment,use the crystal and LC bandwidth filter adjustment procedures inChapter 2.If a defective bandwidth filter board is suspected, refer to “IFPower-Level Measurement” in Chapter 5.i found in the Agilent forum this discussionhttp://www.home.agilent.com/owc_discussions/thread.jspa?messageID=59931&tstart=0but it seem to be more related to the option 130 (which i have but can't test that since it stuck at 1khz).Now if anyone can tell me if there a easy and not intrusive test or thing i can do to be sure it's only a calibration issue, i still have some time to return the unit but i don't want to pay someone half the price i paid to troubleshoot this unit to found it was a hardware failure.When i test manualy i can see a drop in the 1 khz and 300 hz range but this disappear if i enable the correction option in the cal menu. So i'm stuck here, calibration or hardware error?? since i still get an error for the AMPL cal test.Thanks in advance for your help.

author: willb
author_rank: Regular Contributor
timestamp: February 15, 2014, 02:59:58 pm
content: My 8591A had the same issue. Mine wasn't failing at the 1Khz RBW filter, I think it was the 30Khz(can't remember). I rigged up some LC shorting crystals as described in the manual, and carried out the adjustments of the A11/A13, basically peaking them for max amplitude. My SA now passes it's self cal perfectly every time.

author: AwArD_RzD
author_rank: Regular Contributor
timestamp: February 16, 2014, 03:36:49 am
content: I manually tested all the range multiple time under 1khz and i found all the result is way off and i can repeat these result so no intermittent drift here.The 300 Hz show -24.91 dBmThe 100 Hz show -26.54 dBmThe 30 Hz show -35.30 dBm.these should be around -20 dBm (+- 2.2 dB) as the troubleshooting guide say.I did more research today and the little info i found is when the problem is under the 1khz range, it's the add on board fault and there no adjustment. The board should calibrate itself (in theory) if the information i found are true.Thanks for the info Willb. I was near to try this route to see if this change something but the seller replied and he offer a replacement, (same model, same option) so i will wait to receive the other unit. Good to know if i get this error in the future for the upper RBW this can be re calibrated with this procedure.If i have some feedback about this (if the seller give me news about the problem) i will update this thread for future people who might have this issue.

author: dxl
author_rank: Regular Contributor
timestamp: July 24, 2014, 02:39:02 pm
content: Hi,did you ever fix that issue? I'm having the same problem with a HP 8596 SA. All BWs are fine, but the 1KHz RES BW Amplitude is off by around 6db. Would be interested how you fixed it.Thanks

author: dxl
author_rank: Regular Contributor
timestamp: July 24, 2014, 07:18:11 pm
content: Seems like the 21.4MHz crystal filter on my Bandwidth Amplifier Board is broken. The Agilent Part number is 0410-2118, but it's no longer available. Does anybody know the specs of those filters?Thanks

author: AwArD_RzD
author_rank: Regular Contributor
timestamp: July 28, 2014, 01:15:50 am
content: I returned the unit and the guy never told me the problem with the SA and the only person who was able to help me with that told me, if this is a crystal/filter issue you need to replace them with a matched batch. Recently i saw somewhere there some transistor who can cause this issue but i don't remember where i saw that, if i find it i will post the link.