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Vladan,

I was a little too brief (confusing) in my first point. I was using a battery operated signal source to put a test signal on the 3585a, not to power the 3585a.

I have conducted the suggested test using a Fluke 189. I get no voltage across any of the BNC shells or the 3585a chassis.

Thanks for sticking with me on this. I really would like to get it to work.

Gordon.


--- In hp_agilent_equipment@..., "pianovt" wrote:

Hi Gordon,

I assume the battery operated source is a battery with an inverter that creates 120Vac/60Hz, right? Does the inverter output have a safety ground that is connected to earth?

If not, please do the following experiment. Disconnect everything from the 3585 except for the power cord and plug it into your usual ac line socket. Turn the 3585 on. Take a multimeter and put it on AC Volts . Attach one lead of the meter to something that you know is grounded (earth) and touch the other meter lead to the BNC shells and any conductive chassis parts on the 3585. Is there any measurable voltage?

Vladan

--- In hp_agilent_equipment@..., "gldinnc" wrote:

Thanks to Vladan, Ken and Ed for their suggestions.

I did a little more testing. Here is what I found:

1. With a battery operated source, everything seems fine.
2. If an external ground is connected to the ground of the tracking generator BNC or the external trigger BNC, no spikes appear.
3. Connecting external ground to the 1meg or 50/75 ground generates spikes.
4. If the span is less than 500kHz the spikes disappear (or seem minor), but if the span goes from 499,999 to 500,000 they hop up to the reported level.

While I can pull the covers off and begin to test power supply ripple, I would hope to get a little more directed.

Thoughts?

Gordon, KA2NLM