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

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. > > 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 > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

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@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. > > > > 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 > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

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@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@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. >> > >> > 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 >> > _______________________________________________ >> > time-nuts mailing list -- time-nuts@lists.febo.com >> > To unsubscribe send an email to time-nuts-leave@lists.febo.com >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > >

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@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@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@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. > >> > > >> > 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 > >> > _______________________________________________ > >> > time-nuts mailing list -- time-nuts@lists.febo.com > >> > To unsubscribe send an email to time-nuts-leave@lists.febo.com > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com