Hello all, Thanks for letting me join. I just built a GPSDO from some junk I had lying aroundI used a Navman GPS Jupiter 12 and an Isotemp 118-12 which can be controlled by the NavmanThe Isotemp is controlled by the heater in it which can be controlled by external DC signal. The Navman puts out a 10 KHz square wave and I compared this to the divided 10 MHz OXCO output thru a XOR. The XOR output is rectified to DC and used to control the Isotemp. I divided the 10 MHz with three 74LS90 DIPsI think this is pretty old stuff.I believe the thing works, my 10 KHz square waves line up nicely at a stable distance after a while and the output seems stable. It seems stable at 500 MHz harmonic. I cannot see even a one Hz change at 500 MHz on any of my equipment, such as it is. Is there an easy way to put an indicator on this thing so I know when it is locked, rather than using a computer or hooking up my scope?Any suggestions on how to get more information from the GPS unit without using a computer? Like designing a readout for time or whatever?Just looking for ideas before I button the thing up in it's new case. Wally KC9INK

Congratulations on the fun project. Well the easiest thing is to use two level comparators on the filtered DC. One for high and the other for the low trip point. Then feed a LED or a set reset flip flop so you have a memory. Unlocks are a challenge in that everything may work just fine but then a slip occurs. It relocks and you never know it. Just keeping inline with the approach you have used so far. You can absolutely create more advanced solutions. Just dislike a detector more complicated than the system. Good luck Paul WB8TSL On Wed, Jun 8, 2022 at 1:44 PM W Private via time-nuts < time-nuts@lists.febo.com> wrote: > Hello all, Thanks for letting me join. I just built a GPSDO from some junk > I had lying aroundI used a Navman GPS Jupiter 12 and an Isotemp 118-12 > which can be controlled by the NavmanThe Isotemp is controlled by the > heater in it which can be controlled by external DC signal. > The Navman puts out a 10 KHz square wave and I compared this to the > divided 10 MHz OXCO output thru a XOR. The XOR output is rectified to DC > and used to control the Isotemp. > I divided the 10 MHz with three 74LS90 DIPsI think this is pretty old > stuff.I believe the thing works, my 10 KHz square waves line up nicely at a > stable distance after a while and the output seems stable. It seems stable > at 500 MHz harmonic. I cannot see even a one Hz change at 500 MHz on any of > my equipment, such as it is. > Is there an easy way to put an indicator on this thing so I know when it > is locked, rather than using a computer or hooking up my scope?Any > suggestions on how to get more information from the GPS unit without using > a computer? Like designing a readout for time or whatever?Just looking for > ideas before I button the thing up in it's new case. > Wally KC9INK > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com >

On Wednesday, June 8, 2022, 2:04:08 PM EDT, paul swed via time-nuts <time-nuts@lists.febo.com> wrote:  

That particular approach about monitoring the control voltage may have to wait until I get the thing all buttoned up and insulated because the control voltage changes even with the temp in the room. The oven is insulated, but apparently not perfectly. I did put the heatsink for voltage control in contact with the oven osc and did notice a big change in control voltage. Maybe 1/2 volt. It might drop another half volt. Trying to conserve the heat and use less power and hopefully get more stability, even though I cannot measure it . I figure that a little insulation is free anyway. Thanks, Wally On Wednesday, June 8, 2022, 2:04:08 PM EDT, paul swed via time-nuts <time-nuts@lists.febo.com> wrote: Congratulations on the fun project. Well the easiest thing is to use two level comparators on the filtered DC. One for high and the other for the low trip point. Then feed a LED or a set reset flip flop so you have a memory. Unlocks are a challenge in that everything may work just fine but then a slip occurs. It relocks and you never know it. Just keeping inline with the approach you have used so far. You can absolutely create more advanced solutions. Just dislike a detector more complicated than the system. Good luck Paul WB8TSL On Wed, Jun 8, 2022 at 1:44 PM W Private via time-nuts < time-nuts@lists.febo.com> wrote: > Hello all, Thanks for letting me join. I just built a GPSDO from some junk > I had lying aroundI used a Navman GPS Jupiter 12 and an Isotemp 118-12 > which can be controlled by the NavmanThe Isotemp is controlled by the > heater in it which can be controlled by external DC signal. > The Navman puts out a 10 KHz square wave and I compared this to the > divided 10 MHz OXCO output thru a XOR. The XOR output is rectified to DC > and used to control the Isotemp. > I divided the 10 MHz with three 74LS90 DIPsI think this is pretty old > stuff.I believe the thing works, my 10 KHz square waves line up nicely at a > stable distance after a while and the output seems stable. It seems stable > at 500 MHz harmonic. I cannot see even a one Hz change at 500 MHz on any of > my equipment, such as it is. > Is there an easy way to put an indicator on this thing so I know when it > is locked, rather than using a computer or hooking up my scope?Any > suggestions on how to get more information from the GPS unit without using > a computer? Like designing a readout for time or whatever?Just looking for > ideas before I button the thing up in it's new case. > Wally KC9INK > _______________________________________________ > 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

On Wed, June 8, 2022 12:59 pm, paul swed via time-nuts wrote: > Well the easiest thing is to use two level comparators on the filtered DC. > One for high and the other for the low trip point. That only tells you if the PLL is locked to the PPS output, it does not tell you if the PPS output is valid. > On Wed, Jun 8, 2022 at 1:44 PM W Private via time-nuts < >> Is there an easy way to put an indicator on this thing so I know when it >> is locked, rather than using a computer or hooking up my scope? You will need to check the output messages from the GPS receiver to see if the GPS is receiving enough satellite. That is 9600 baud serial text, so a microcontroller can do it. Paul's recommendation for checking whether the PLL is locked is really only useful after you know that the signal you are tracking is actually valid. -- Chris Caudle