Re: [time-nuts] "The Penultimate HP5065 A15"
Having one of the best HP5065A Rb's that Corby has seen right at 4 E-14 at 200 and 400 sec. I have been hands off. My age and macular hole on my right eye has impacted my hardware work. A recent test also shows very low aging over a 9 month period. But last September my environmental monitor was with Tom. The last month I have spend strictly on temperature to better understand what lab temperature effects the Rb. This moment a 48 hour frequency test is in the works because there is a tropical storm that was a hurricane 20 miles east from me. Hope there are no power failures because the Rb is not on a UPS but like all my frequency equipment is on a Power Line Conditioner including the Rb. No power failure I will be able to share frequency versus pressure and temperature. C field control Corby included by my request a fine control using a Vishay trim pot, knowing what I know today I would make the trim pot the coarse and the original Hp the fine. There is little need for coarse adjustment. On the A 15 subject I keep hands off but Juerg is making some changes. In the AC mode there is up to 20 W heat generated between the transformer and the 24 V DC input. Our answer is a Buck Converter on the output of the AC supply down to 16 V for the Li Ion module that in turn feeds a Mean Well SD-50A-24 DC?DC converter. It 24 V output is not adjustable but that is a small price to pay. We have done tests feeding an OSA 8600 directly and have not seen any degradation. But in this case the A 15 board still does its part. The parts are not in the Rb but behind on the back. A pressure, temperature and two DAC board is in the works. Next hurricane the tests will be on a FRK/M100 because that will be my future HP5065A replacement. Bert Kehren Palm City Florida In a message dated 8/2/2020 4:38:31 AM Eastern Standard Time, time-nuts@lists.febo.com writes: Regarding 5065 "A15" When I was about to repair my 5065, the first thing I noticed was thequite high "+22-30V" and its impact on the dissipated heat from theseries regulator Q1. Therefore, I replaced the power transformer T1and the rectifiers with a linear regulated power supply providingfiltered 24V DC. The original circuitry incorporated a battery charger A2but since the accus was (very) dead, it was replaced with a diodejumper board A18 from a second scrapped unit. The original diodesgot hot. They were replaced with modern types. I will follow your progress with the new regulator board with great interest. Best Regards Ulf KylenfallSM6GXV___time-nuts mailing list -- time-n...@lists.febo.comTo unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] "The Penultimate HP5065 A15"
tim...@timeok.it writes: >A better C field generator is necessary and the LM399 remains a good > solution. It would be interesting to add > barometric pressure compensation. I don't think I can fit that also :-) > Two types of setting could be used to adjust the C field, one with fixed high > stability resistors resistors that can be switched for the coarse and a > potentiometer for fine tuning in order > to mitigate its low temperature stability. already got that. >Excellent solution of two separate power supplies for the lamp and the > rest of the electronics but I have > doubts about the LM317. Since we already have the LM399 available for the > CField, why not use this reference > voltage already present on the board to drive two low noise regulators? That's precisely the plan, but I like the LM317 style short-circuit and thermal protection, so I will probably do it by setting the LM317 voltage with a voltage divider, and then drive the midpoint with an op-amp relative to the LM399 -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] "The Penultimate HP5065 A15"
Regarding 5065 "A15" When I was about to repair my 5065, the first thing I noticed was the quite high "+22-30V" and its impact on the dissipated heat from the series regulator Q1. Therefore, I replaced the power transformer T1 and the rectifiers with a linear regulated power supply providing filtered 24V DC. The original circuitry incorporated a battery charger A2 but since the accus was (very) dead, it was replaced with a diode jumper board A18 from a second scrapped unit. The original diodesgot hot. They were replaced with modern types. I will follow your progress with the new regulator board with great interest. Best Regards Ulf Kylenfall SM6GXV ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] "The Penultimate HP5065 A15"
It has been a while since there has been talk of a redesign of the A15 and it is certainly the right way to technologically update the HP5065A that deserves better electronics. A better C field generator is necessary and the LM399 remains a good solution. It would be interesting to add barometric pressure compensation. Two types of setting could be used to adjust the C field, one with fixed high stability resistors resistors that can be switched for the coarse and a potentiometer for fine tuning in order to mitigate its low temperature stability. Excellent solution of two separate power supplies for the lamp and the rest of the electronics but I have doubts about the LM317. Since we already have the LM399 available for the CField, why not use this reference voltage already present on the board to drive two low noise regulators? I hope to be of contribution to this project. Luciano Luciano P. S. Paramithiotti tim...@timeok.it www.timeok.it Da "time-nuts" time-nuts-boun...@lists.febo.com A time-nuts@lists.febo.com Cc Data Fri, 31 Jul 2020 21:31:13 + Oggetto [time-nuts] "The Penultimate HP5065 A15" The A15 board in one of my 5065s is in bad shape, and I have started to look at designing a plug-compatible replacement board. The main reason I dont just repair/replace the A15 is that I want to find out how much instability the PSU contributes. The outline idea currently is: LM399 self-biased voltage reference (See: Linear app-note 42, fig 72) The ultimate board would use LTZ1000, but I have not quite convinced myself yet, even if it would be cute to have a HP5065 which delivered both precise frequency and voltage :-) Op-amp based C-field driver Vishay SMR1DZ resistors for VREF/C-field stability C-field polarity switch. An experiment. If nothing else I will be able to measure the residual magnetic field. Optional adjustable C-field. Optional because the pot may degrade the C-field stability. Two +20V on-board LM317-style linear regulators, one for the lamp, one for the rest. Split for noise reasons and to be able to play with the lamp voltage/power. One or two pre-regulator current measurement shunts. DC/DC-brick switchmode -20V supply with brutal filtering. The downside of the two linear +20V regulators is that even with a heatsink, they will probably get hot-ish if the internal DC bus is too much over 24VDC. For this reason, and because I may simply run out of PCB space, I may leave the bridge rectifier out, so it will only works with EXT-DC. I'll post kicad schematic once I get further. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] book could be interesting 4 you
OOOhps, that was not intended for here. :-) Looks like Thunderbird has messed up the address data base. But at least it's on-topic. Gerhard ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] book could be interesting 4 you
< https://epdf.pub/discrete-oscillator-design-linear-nonlinear-transient-and-noise-domains.html > And there is more! cheers, Gerhard ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
