Re: Z3801A questions
Gang,
I don't know if this will do the job for you, but
I've replaced defective switchers in my 2 DATUM
9390's with these as external supplies.
https://www.ebay.com/sch/i.html?_nkw=cisco+34-0874-01&_svsrch=1
They are +/- 12 volts and 5 volts. My two
DATUM's have been running on two of these
supplies for over 7 years with no hiccups. Plus, they're inexpensive!
Burt, K6OQK
At 02:43 PM 5/20/2023, you wrote:
Yeah, you guys are thinking like Iâm thinking. I really donât 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@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 11:42â¯AM Bob Camp via time-nuts <
time-nuts@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@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.
Iâve 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.
Iâve read the material on 56V vs 48V switching supply startup for
these, and I will them that next. Failing that, Iâll 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 Iâm 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, Iâm 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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Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
biwa@att.net
K6OQK