[volt-nuts] [Bulk] Re: 3458A reference boards on ebay

[Randy Evans]

The reference module is in a metal box and uses an external linear PS with
internal separate regulation.  I don't think its external EMI, but anything
is possible.

Randy

On Wed, Jan 28, 2015 at 10:28 PM, Hendrik Dietrich <don_hendi at gmx.de> wrote:

>
> Am 29.01.2015 04:07, schrieb Randy Evans:
>
>> I bought two HP-3458A ref boards from John Daly (he no longer has any
>> more)
>> and they worked fine but have intermittent noise bursts.  I suspect they
>> were rejects from HP/Agilent.  At some point I will probably replace the
>> LTZ1000As and reduce the internal temperature set point for better
>> stability.  Has anyone else had any issues with these units?
>>
>> BTW, I packaged the units in an enclosure for a stand-alone reference and,
>> except for the occasional noise bursts, seem very stable according to my
>> HP
>> 3458A and fluke 732A/ESI RV722 KVD.
>>
>> Randy
>>
>>
> Hi Randy,
>
> Noise bursts, especially if they get back on track again, sound like
> electromagnetic interference from your short description.
> If applicable, turn of the CFL or LED lighting, replace the switch-mode
> power supply with a linear one or even better a battery,, try a known
> non-reject in place of the ebay reference module, spread some capacitors
> on/around the module and/or invest in a metal box.
>
> Hendrik
>
>
>
>
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