[time-nuts] Any HP8561B Experts out there

[John Miles]

Someone on hp_agilent_equipment may be more likely to recognize the
rebooting symptom.  It's likely to be a matter of something heating up and
loading down the supply, or otherwise triggering the CPU's power-failure
signal.  Hang a scope on it and see if anything comes to mind, and try R134a
and a heat gun as well.  The power supply is somewhat well-concealed in
these but they're easy to work on otherwise.

Is the response actually correct at 1 MHz and above?  In AC-coupled mode the
lower limit is 100 kHz.  An open attenuator element or other interconnection
is what normally causes decreased LF reponse but you normally see huge
losses below 100 MHz in that case.  Check the flatness everywhere, not just
at the low end, and see if it's otherwise in spec.

-- john, KE5FX


> Hello,
>
> I just bought a HP8561B on ebay but it has a few faults.
>
> 1.  The unit powers up and basically operates ok.  But after a while, it
> turns off, turns back on, goes through the start sequence, and
> then stays on
> for a few minutes and turns off again.  It cycles through this.
> 2.  Sometimes at some settings it does stay on for a while (20
> mins) other
> times it justs keeps re-booting.
> 3.  The frequency response also falls off below 1 MHz, to -40
> down at 1 kHz.
> I assume this is the first mixer.
>
> Any one have any ideas before I waste $600 in shipping costs and send it
> back to the US (I'm in the UK).
>
> Regards
>
> Martyn
>
>