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HP8753B Time Domain Measurement

Question asked by broadcastRF on Jul 18, 2010
Latest reply on Jul 28, 2010 by broadcastRF
Previously I have used the HP8753B for impedance measurements only, mostly with tuned circuits, diplexers, and antennas.  Now I have a need to measure cables and transmission lines.  The unit has option 010.  When I attempt to duplicate the frequency and time domain measurements as demonstrated in the directions, I have a problem.  The trace jumps up and down from top to bottom repeatedly, once I activate the autorange.  Only briefly do I see the measurement I have made go zipping by.  The autorange seems to work fine on everything else.
      I was able to repair the A3 source several months ago.  The final amplifier stage was bad. In terms of AM and FM noise, the A3 appears to compare with my HP8657B synth.  The amplitude does not go as high as it once did, but it is usable to +15dbm.  I have noticed that the unit fails ADC linearity test # 17, and so I swapped the A10 digital IF card, but had the same results on test #17 and the time domain.  All of the sampler IF cards seem to be good, and seem to have the same noise floor, with the noise having a range of .015db, when connected to the source through a splitter/ attenuator and autoranged.  I use the HP 85046A test set with the unit.
      Also, the A3 Id+/Id- voltage is .136 volts, instead of the .380 to .485 range that is printed on the A3 sticker.  Also,what is the purpose of CAV Adjust trimmer on the A3?