[time-nuts] Re: Z3801A questions

[paul swed]

The +/-15 higher current is used for opamps and the oven heater as I
recall. It goes across the two supplies.

On Sat, May 20, 2023 at 11:51 PM Mahlon Haunschild via time-nuts <
time-nuts at lists.febo.com> wrote:

> Yeah, you guys are thinking like I’m thinking.  I really don’t feel like
> spending time sorting out the power supply when all I really need to do is
> pull the two DC-DC converters and connect up my triple supply.
>
> Btw, one converter is +-15VDC, 830 mA and +5V 5A (25W total combined) the
> other one is +5V 4A.
>
> Best regards
>
> Mahlon - N4ZK
>
> On Sat, May 20, 2023 at 12:17 PM paul swed <paulswedb at gmail.com> wrote:
>
> > Mahlon I am aware that the big black block that is a DC to DC converter
> > does fail.
> > So as you suggest absolutely just replace it with a AC to DC multiple
> > output unit. Think it was +12 -12 +5. But the schematics and such show
> what
> > the voltages are.
> > The other thing is the input circuit to the unit can also fail. Its all
> > pretty reasonable to troubleshoot or get rid of if you do not intend to
> run
> > on batteries. My Z3801 has never been run on batteries. Though I have 2 X
> > 24 V linear supplies in series for it. Been working fine for 15 years or
> > more. I am knocking on wood right now.
> > Regards
> > Paul
> > WB8TSL
> >
> > On Sat, May 20, 2023 at 11:42 AM Bob Camp via time-nuts <
> > time-nuts at lists.febo.com> wrote:
> >
> >> Hi
> >>
> >> First step would be to look for melted blobs / debris where capacitors
> >> used to be …..
> >>
> >> Bob
> >>
> >> > On May 19, 2023, at 9:17 PM, Mahlon Haunschild via time-nuts <
> >> time-nuts at lists.febo.com> wrote:
> >> >
> >> > Hello list.  Just joined and, after reading the list archives, I feel
> >> that I Am Not Worthy to ask these questions, but here goes.
> >> >
> >> > I’ve had a Z3801A just sitting around for years now and, the other
> day,
> >> I finally decided to experiment with it a bit.  I already had a 26dB
> Andrew
> >> antenna and a Vicor 48V 2.9A power supply for it, so I put the antenna
> on
> >> the back of the receiver with some N adapters, wired up a serial cable
> to
> >> an ancient ThinkPad running SatStat, placed the whole rig in the back
> yard,
> >> and turned everything on.
> >> >
> >> > To my astonishment, after placing it into survey mode, four hours
> >> later, it had completed its sky search and had switched over into
> position
> >> hold, with a  TFOM of 3 and a FFOM of 0.  Since all I wanted it for was
> to
> >> use as a freq reference, I thought it was good to go.
> >> >
> >> > The next day I tried it again.  No go.  The Z3801A acted like it had
> >> developed an internal power supply short because it was causing the
> Vicor
> >> to go into current limiting, with zero volt output.
> >> >
> >> > I’ve read the material on 56V vs 48V switching supply startup for
> >> these, and I will them that next.  Failing that, I’ll troubleshoot the
> >> power supply.
> >> >
> >> > It appears that a long time ago someone reverse-engineered the power
> >> supply design and published a schematic for it, and Google found it
> >> somewhere in https://xdevs.com/doc/HP_Agilent_Keysight/ <
> >> https://xdevs.com/doc/HP_Agilent_Keysight/> but is it on the web
> >> elsewhere?
> >> >
> >> > If all else fails I’m tempted to yank the two DC-DC converters from
> the
> >> power supply board and power the whole thing with a suitable AC-DC
> >> triple-output switcher (specifically, a Nemic Lambda LWT-50H-5FF, which
> is
> >> on hand).  Has anyone done this?
> >> >
> >> > Lastly, I’m considering trying an Oncore UT+ instead of the VP to get
> >> its better front-end filtering.  Opinions?
> >> >
> >> > Best regards and thanks in advance,
> >> >
> >> > Mahlon - N4ZK
> >> > _______________________________________________
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> >
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