[time-nuts] Re: Death of a Capacitor
Hi, For spikes and RF, common ground is a chimera, a bed-time story for kids. The quicker you learn to understand that "ground wire" or "ground connection" is just another wire that has resistance, induction, various offsets and different noise, the "common" part is very much a "Your Mileage May Vary" issue. Concepts to learn is common mode and differential mode, and their handling is different. Common mode suppression may be useful, or damage your application. Spikes travels nicely, but local decoupling help to reduce the issue. Spikes travels easily through regulators if you have not added capacitors to handle it and inductors to object to it. What people do not think of is that it's the rise time that defines the path, not the frequency. So sharp spikes from 50 Hz may go through, even if 50 Hz as frequency is well filtered, but not the spiked signal. Snubbers (resistor in series with cap) can help, as it provide a path for the spike to go into a resistor. There is nice books to help with practical engineering on this. Check out Ott for instance. Cheers, Magnus On 2021-09-27 00:56, Bob kb8tq wrote: Hi Once you put big inductors in the ground path …. it’s not a common ground anymore. Bob On Sep 26, 2021, at 6:53 PM, Gerhard Hoffmann wrote: Am 27.09.21 um 00:34 schrieb Bob kb8tq: Hi If you start dumping major current spikes into a common ground, it’s amazingly difficult to get rid of the results. First Principles know the law of the conservation of spikes: Capacitors convert voltage spikes to current spikes. Inductors convert current spikes to voltage spikes. Gerhard (who just has fun with a new LMX2594 synthesizer board. 10 MHz to 15 GHz, 2 cm**2, 20 dBm, limited amount of empty boards available for free. Soldering them is NOT harmless.) ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Death of a Capacitor
Hi Once you put big inductors in the ground path …. it’s not a common ground anymore. Bob > On Sep 26, 2021, at 6:53 PM, Gerhard Hoffmann > wrote: > > > Am 27.09.21 um 00:34 schrieb Bob kb8tq: >> Hi >> >> If you start dumping major current spikes into a common ground, it’s >> amazingly difficult to >> get rid of the results. > > First Principles know the law of the conservation of spikes: > > Capacitors convert voltage spikes to current spikes. > > Inductors convert current spikes to voltage spikes. > > Gerhard > > > (who just has fun with a new LMX2594 synthesizer board. > > 10 MHz to 15 GHz, 2 cm**2, 20 dBm, limited amount of empty > > boards available for free. Soldering them is NOT harmless.) > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Death of a Capacitor
Am 27.09.21 um 00:34 schrieb Bob kb8tq: Hi If you start dumping major current spikes into a common ground, it’s amazingly difficult to get rid of the results. First Principles know the law of the conservation of spikes: Capacitors convert voltage spikes to current spikes. Inductors convert current spikes to voltage spikes. Gerhard (who just has fun with a new LMX2594 synthesizer board. 10 MHz to 15 GHz, 2 cm**2, 20 dBm, limited amount of empty boards available for free. Soldering them is NOT harmless.) ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Death of a Capacitor
Hi If you start dumping major current spikes into a common ground, it’s amazingly difficult to get rid of the results. Bob > On Sep 26, 2021, at 6:21 PM, John Ackermann N8UR wrote: > > I got some interesting and unintended data today. I was measuring low phase > noise oscillators using a set of power supplies I just finished putting > together. > > The configuration is ~24 VDC into a TPS-53400 switching regulator that > outputs 19.2 volts at up to 3 amps. That output is fed to separate regulator > boards for each oscillator. Those boards each have an LT-1086 linear > pre-regulator that drops the input to about 17 volts, which then goes into an > ultra-low-noise LT3045A outputting 15 volt to drive the oscillator. So there > are two linear regulators and lots of caps, inductors, and ferrite beads to > isolate the oscillators from the switching supply. > > Due to an error by an assembly tech who will remain nameless, the wrong > electrolytic was installed on the output side of the switching regulator. It > should have been 33uF at 50 volts, but what got installed was 330 uF at 16 > volts, so it was rated below the operating voltage. (I was building two > boards at the same time, one for 5V and one for 19.2V. Apart from the voltage > setting resistor, the only difference between the two was the output cap. I > managed to swap them.) > > I tested the system on the bench for 24 hours and everything worked fine, so > I buttoned up the enclosure and started a 4 hour data capture. About 70 > minutes in, the electrolytic became very unhappy and whatever it turned into > caused the switcher to start spewing all sorts of crud. The regulator kept > working (sort of) through the end of the run, but when I came into the lab > the next morning it had shut down completely and troubleshooting showed that > the cap had shorted at some point after the run completed, and the regulator > chip went into shutdown. > > Attached are a plot of frequency showing the whole run with the very obvious > change when the cap failed, and another zoomed view of the critical moment. > The failure was very abrupt with no visible lead-in. > > What I find interesting is that all that crud got through not one, but two > linear regulators, one of which is touted for its extremely high PSRR (and I > did my best to follow the recommended PCB layout for that chip). That must > have been one ugly 19V line when the cap went... > > John > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: OCXO Datasheet search
Jim, That oscillator was a component in the old AN/USM-247V Versatile Avionics Shop Test (VAST) automatic test system for Naval avionics systems. Many years ago, I was a civil servant at the Naval Aviation Depot in Jacksonville, FL. While there, I was one of a team of technicians that maintained and calibrated the VAST system. Before that, I was a software engineer that wrote and maintained the Test Program Sets (TPS) that tested and diagnosed component failures in the systems and circuit boards that ran in many of the Navy's combat aircraft. At one time, I had access to much of the original engineering specs on the system, including most of the components in the VAST equipment. Alas, that was in the latter years of the 20th century. The VAST system has long been decommissioned and scrapped. Most likely all of that data has been scrapped along with it. Those oscillators were nothing exceptional, as I remember; probably in the neighborhood of parts in 10e-9 for aging and temperature stability. They were 1970s technology, since the VAST system was developed in those years. If you have any contacts in the Navy or possibly someone in an engineering support activity, they might be able to do some research for you. Sorry I can't help more, but I've been retired from that activity for nearly 20 years, and all of my contacts where I worked are now gone as well. Dave M From: "Jim Flanagan" To: time-nuts@lists.febo.com Sent: Saturday, September 25, 2021 9:59:18 PM Subject: [time-nuts] OCXO Datasheet search Hi - I posted a request a number of years ago and wanted to make another attempt to track down some specification data on a NOS 10 MHz OCXO that I have in my possession. It had a NSN # of _5955-00-165-1665_ and was produced by several mfrs back in the mid to late '70's : 1630-2R Adatum (Austron) 30294613 Adatum (Austron) YHS22-44 Crown Pump Co. YHS22-44 Greenway Industries 247ASC0393-001 Naval Air Systems Command If anyone has any data that they would be willing to share, it would be appreciated. I actually posted this request several years ago and thought I would give it another try. Thanks Jim ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Failed HP 58503A VFD Segments
Hello, Since the display is quite similar to the 34401A one (and some other units of that era), it probably will use the same driver IC, SN75518 Regards, Javier On 26/9/21 21:03, ed breya wrote: There should a number of types. I looked in the manual for my Gigatronics 7200, which has VFDs and is probably from the same era, and found they used NE594s. Ed ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Failed HP 58503A VFD Segments
There should a number of types. I looked in the manual for my Gigatronics 7200, which has VFDs and is probably from the same era, and found they used NE594s. Ed ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: OCXO Datasheet search
Hi Ok, there are a bunch of typos there ... > On Sep 25, 2021, at 10:59 PM, Jim Flanagan wrote: > > Hi - > I posted a request a number of years ago and wanted to make another attempt > to track down some specification data on a NOS 10 MHz OCXO that I have in my > possession. It had a NSN # of _5955-00-165-1665_ and was produced by several > mfrs back in the mid to late '70's : > > 1630-2R Adatum (Austron) Austron became part of Datum and Datum ultimately became part of Microchop > 30294613 Adatum (Austron) > YHS22-44 Crown Pump Co. I very much doubt a pump outfit actually made OCXO’s > YHS22-44 Greenway Industries Should be Greenray, which then became part of NDK(?) > 247ASC0393-001 Naval Air Systems Command > > If anyone has any data that they would be willing to share, it would be > appreciated. I actually posted this request several years ago and thought I > would give it another try. A lot of this stuff shows up on various sites on the internet. It’s all a bit suspect, just as the often found description of “oscillator non-crystal controlled” is a bit suspect. Given the state of the art / OEM market back in the mid 70’s and Greenray as a supplier, it’s a pretty good bet the specs are pretty loose compared to a “modern” $4 Chinese eBay part …. Some stuff has come a long way in 50 years ... Bob > Thanks > Jim > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] OCXO Datasheet search
Hi - I posted a request a number of years ago and wanted to make another attempt to track down some specification data on a NOS 10 MHz OCXO that I have in my possession. It had a NSN # of _5955-00-165-1665_ and was produced by several mfrs back in the mid to late '70's : 1630-2R Adatum (Austron) 30294613 Adatum (Austron) YHS22-44 Crown Pump Co. YHS22-44 Greenway Industries 247ASC0393-001 Naval Air Systems Command If anyone has any data that they would be willing to share, it would be appreciated. I actually posted this request several years ago and thought I would give it another try. Thanks Jim ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: 10 mhz distribution
I use an analog video distribution amplifier it has one input and 8 outputs. I got it at a ham radio swap meet for $5.00 and it works great. It has BNC input and outputs and a built-in power supply. Sent from my Verizon, Samsung Galaxy smartphone by Morse code. Original message From: Louis Taber Date: 9/25/21 6:47 PM (GMT-08:00) To: Discussion of precise time and frequency measurement Subject: [time-nuts] Re: 10 mhz distribution I have had good luck with the TAPR amp.https://tapr.org/product/tadd-1-rf-distribution-amplifier/On Friday, September 24, 2021, djl wrote:>> https://www.sv1afn.com/en/gnss-gps/10-mhz-distribution-amplifier.html> has other interesting stuff...> >>___time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.comTo unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
