On Tue, 6 Jan 1998, Bob Tims wrote:
>
> Happy New Year All,
>
> I have an interesting noise problem brought to me.
> The noise is a 500-900 mV pulse seen at 50 MHz on a
> power lead from a DC to DC converter (48V to 5V) to a
> VME cage.
> There were two scenarios: first, both the power supply
> and the cage are earth-grounded, and the pulse is seen
> at both the power supply and the cage. Second, the cage
> is left floating, and the pulse is only seen at the
> power supply.
> The noise seems to be a ring, and the leads between the
> supply and cage are fairly long.
> Has anybody seen something like this before, or does anybody
> have any suggestions or comments?
> We have several ideas, but not much time.
> The frequency and the fact that the pulse reaches almost a volt
> concerns us greatly.
> Thanks in advance,
>
> Bob Tims
> Standards and Compliance
> rt...@emx.ericsson.se
>
> The opinions expressed in this correspondence in no way reflect
> the opinions of Ericsson Inc.
>
>
> RCIC - http://www.rcic.com
> Regulatory Compliance Information Center
>
Hi Bob,
My first question is how are you measuring the pulse? The exact apparatus
and means of connection can completely change the result. There is some
chance the problem does not really exist except for problems in the
measurement. Even if the measurement is clean, knowing how the problem
was measured may lead to a clue as to its solution.
Doug
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___ _ Doug Smith
\ / ) Manager EMC Development & Test
========= Auspex Systems
_ / \ / \ _ 5200 Great America Parkway
/ /\ \ ] / /\ \ Santa Clara, CA 95054
| q-----( ) | o | Phone/FAX: 408-986-2157/2020
\ _ / ] \ _ / Email: dsm...@auspex.com
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