CuriousMarc - 2025-01-21
Just as we were going to do some exciting relativistic atomic clock experiments, one of the clocks went down. Oh well, the bright side is that we get to look in the innards of this very complicated instrument. Atomic Clock Playlist: https://www.youtube.com/playlist?list=PL-_93BVApb59F6V90OdcqVofqVWceR6Dk How an atomic clock works: https://youtu.be/eOti3kKWX-c Atomic clock Zeeman alignment: https://youtu.be/xTy1kY_wtsY Hi-res scan of the HP 5061A manual: https://archive.org/details/hp-5061-a-cesium-beam-frequency-standard-operation-and-service-manual-05061-9052-june-1978 Stuff that supports the channel: - Support us on Patreon: https://www.patreon.com/curiousmarc - Amazon links for the tools I use in the lab: https://www.curiousmarc.com/amazon-links - Channel merch on Fourthwall: https://curiousmarc-shop.fourthwall.com - Legacy channel merch on Teespring (I don't have everything transferred to Fourthwall yet): https://teespring.com/stores/curiousmarcs-store "Elevator Music" Credit: Crinoline Dreams by Kevin MacLeod Our lovely sponsors - PCBWay: fast turn PCBs, https://www.pcbway.com - Electro-Rent: https://www.electrorent.com - Keysight: test instruments: https://www.keysight.com - Samtec: connectors: https://www.samtec.com - R&D Microwaves: https://rdmicrowaves.com Get more technical info on the companion site: https://www.curiousmarc.com Contact info: https://www.youtube.com/curiousmarc/about 00:00 Making relativistic experiments with two atomic clocks 03:50 One clock goes down! 04:41 How the HP Cesium clock works 08:03 I think the fault is in the multiplier 11:24 Opening the beast 13:25 Multiplier measurement 15:43 Testing and tuning the multiplier on the bench 18:54 Is there something wrong with 5 MHz input? 21:41 Into the harmonic generator we go 25:07 Back to repairing the multiplier 29:01 It works again!
People think I’m weird because I get excited to see atomic clock repair. I think they’re weird because they don’t get excited for atomic clock repairs 😂
I think you're weird, I mean, you seem to be a sentient 1980s 8 bit micro computer.
Cool username.
right?! I love atomic clocks!
I am afraid you are not alone as a weird guy. Consider I am in too.
It's OK to be weird as long as you don't insist that others go out of their way to accommodate or even celebrate your ways.
The third physicist in the photo at 1:20 is Paul Ehrenfest. He was once called "the good conscience of physics". Read up on his tragic fate, it is a sad story about a troubled and almost forgotten genius.
Can we take a moment and truly appreciate those HP engineers and their RF black magic? And the fact it’s all relatively “easy” to troubleshoot and repair? Presuming you have a stash of original HP transistors…
I love these types of videos!!!
and a his gigantic brain and a lifetime of experience! :), thank god it wasn't the SRD, that would be "almost" impossible to find, and even if you get one, he will have to retune the cavity, ouch!.
yeah its pretty cool. i was surprised to learn how much stuff hp has made as i thought they only make computers😅
I came to comments to mention the level of engineering that went into this equipment. I'm not really sure that the skillset is there today - as everything is more about writing software rather than bias a transistor!
@pe1dnn They sold the Real HP part (which became Agilent and now Keysight) and kept the Compaq part, after which they also replaced Tru64 Unix (bought with Compaq as Compaq had bought DEC before the HP merger) with HPUX.
Blame HP management in the 1999-2001 timeframe.
I love that they used to give you the internal schematic of custom ICs too or explain what it does. The old service manuals are a great read too.
Not only a repair of an atomic clock, but a repair of a likely original factory defect in an atomic clock! Incredible!
I don't think he actually repaired whatever the defect is, it still had that resistor at max gain and it only barely hit minimum power.
Marc, he's fixing the real tick-tock! Din, Dan, Don.
Stay tuned for the next episode? Both us and the clocks!
Name one other person on this earth who can casually repair an ATOMIC CLOCK
Tom van Baak
Probably Poul Henning Kamp
Come to think of it, i have worked with several people that could repair an atomic clock. They are more common than you might think.
This must be why all the work resurrecting the Apollo gear. Mark et al. are going to launch their own cesium references around the moon to further validate relativity.
Cool - a new CuriousMarc video! Nice way to spend a cold dark winter evening - geeking out on HP equipment :)
Courageously snatched victory from the jaws of defeat, thank you for an enjoyable video.
Well, that was a nail-biter of a repair story! I was on a rollercoaster of emotions watching that one, Marc! I'm glad you were able to get it working again!
Now you will have to try to replenish your supply of unobtainium transistors! :)
At some point, Marc is going to have to invest in a silicon foundry so he can make replacement step recovery diodes; we just can’t keep pilfering them from other units. 😢
@15:40 It did say "Caution, disconnect A4P1 before removing assembly".
it‘s about time 😅 thank you!
The sort of distraction I needed today.
Out of curiosity, did any HP atomic-clocks have an alarm and snooze function? Asking for a friend...
Maybe a socket to turn on a coffee percolator.
Hahaha. Would be cool if they had an option for that!
well, we did see the alarm function in action..
@pe1dnn Did it warn of a disturbance in the force because Marc tuned into the Continuum !
@pe1dnnthat's great, you can connect it to your coffee maker, because you may need the brew for troubleshooting.
I love that all the "twiddly bits" are behind a locked panel!
I was lost at "just ready to do 2 o clock......"I'm a Toolmaker, not a hobbyist, and it takes a LOT of skill and smarts to do what I do, but this is amazing to me that he understands all this stuff.
Amazing diagnosis. I would have been doing component swaps with the working clock.
I feel your pain. The tube in my Symmetricom PRS-45 aged out a few years ago.
Timely!
ISWYDT 🤣
Cool to know that HP once made mission-critical important tech and did it well. Their modern consumer division is a crying shame.
The good old days when HP made extremely cool gear that was actually fixable. I repaired several of their single frequency helium neon lasers over the years. ❤
I still can't get over the blank stares I get when I tell people that atomic clocks are now so precise you can use them to measure changes of altitude with submillimeter accuracy. "WHY AREN'T YOU AMAZED????", I plead. Their answer is nearly always the same: "nerd"
This is just the best channel ever.
Some people driving around with atomic clocks to prove theory of relativity while others argue that the earth is flat and there is not such thing as global warming, etc.
We live in marvellous times, don’t we…
But let’s enjoy this marvel of engineering!
Everyone needs a hobby, You know :-)
I received 2 answers from a single guy that were deleted.
(Those guys already have way too big of a platform for their science denial.)
Blame religion.
Religious people have dug in their heels against science and indeed, education altogether, in an attempt to validate their fairytales.
and those are in power, alas.
4:40 elevator music! Love that part
Old hp gear is truly art. Love my 8555b. 18ghz in the 70s!
21:56 Someone is practicing their Hanon chops on the piano. ❤
This is the most niche comment i saw today. Love it.
Good ear! It’s wifey. God I hate Hanon.
0:20 I could use a yellow light to indicate that on me...
Mine would burn out after a few seconds.
Oh, how I look forward to that cymbal tap!
I remember reading about the 1971 experiment when its results were published.
You are certified vintage!
1955
If my memory is correct, the experiment was covered in an article in TIME magazine, with the same photo you showed in your video. The 1971-1972 academic year was also the year I was taking high school physics with an extraordinarily gifted teacher (for which I later received 8 hours AP credit). We of course covered spectral lines and photon frequencies and electron orbits.I am sure we must have covered the experiment although all I remember specifically was learning that cesium had very closely spaced electron orbits and would produce photons in the microwave range that were being used for hyper-accurate clocks.
Time saver!
Bonjour Marc. J'ai regardé sur Arte un documentaire sur la silicon valley et j'ai été surpris et ravi de te voir dedans. Depuis je sais que c'est Jean Marc!!! J'adore la chaîne, bonne continuation.
For the French speaking community, this Arte YouTube series about Silicon Valley here: https://www.youtube.com/watch?v=g9ZKLeyHyZA . Except for the title, it is excellently well done.
Merci Christophe pour le tuyau ! Du coup j'ai été voir, c'est marrant de voir CuriousMarc parler français :))) Enfin... Jean-Marc donc... Dans l'épisode 2/6... Une sacrée bande de grands seigneurs... Des passionnés fondus d'idées et durs au mal. Fascinant (C) Spock.
Drop on from AvE here. Awesome channel. Subbed.
Bad news! Good news!...
I wouldn't differentiate at all. Mainly because I'd have no idea what I as doing be it on the microwave or digital side. Well done Sir!
HP had some brilliant engineering. 💖 Thank you.
Astonishing! 👍
Almost to the very end I expected a bad mini coax or connector.
Looking back at the video, I feel there is still one of the two in there, I need to investigate further. Bad microcoax from the multiplier maybe? It’s pretty kinked in there.
@CuriousMarc That was based on my experience with what happens when they are kinked, twisted, pinched or stretched. Substituton is often the easiest way to verify, but looking at signal while manipulating the coax might show one end is bad in the installed position.
awesome episode! very interesting! great job. Thank you! And BIG THANKS to old HP for this brilliant schematics and theory of operation
The jumper from your 5 MHz source to the counter at 17:07 looks very much like a segment of "classic" Ethernet coax! I have some feeding my 40m inverted vee antenna. Handy stuff.
thank god it wasn't the SRD, phew!!, i was starting to get worried.
even if you find one, you'll have to retune the cavity... ouch
i absolutely love these videos!.
I was looking at that and thinking that it was going to be a sizable operation just to get down to the clock where you could open it!
Awesome Video, as always. I was very surprised that you didn't have an SMB adapter, since vintage HP gear is full of those. I've had to stop and order some at least twice now, because there are just sooo many connections done with them. Especially in the spectrum analyzers and microwave gear. One day, eager to play with an 8008A, I had the misfortune of discovering SMC connectors too. And yes, custom IC reengineering ensued, although two different ones had failed.
You make some of the best videos Marc. Kudos sir, kudos.
Mr. Curious, this is so far above my paygrade but that´s why I watch it. I gaze at Your gear and admire all the stuff I´ll never get to play with. And You make everything look so easy but that must be experience. I always have a very hard time orienting myself, matching schematic and reality. I have chosen a Grundig Schwebungssummer as project, it is a tube based frequency generator and measuring device that happens to have a sweet power stage I use to play guitar&bass thru. Now, after 50odd years the caps are shot and the tubes weak so I have a try with it. …That´s why I say You guys are way ahead of me. Happy New Year!
Nice timing 😆
daily doze of awsomeness received
He has TWO active hydrogen masers, one of them a vintage Sigma Tau MHM-2010 and the other a more modern Russian Kvarz Ch1-76. I'd hate to think how much the newer one cost.
Even better, he got in touch with me and is helping me out. So he’s a gentleman and a scholar.
I am so jealous. Want to build a rubidium optical clock and femptosecond comb to compensate.
@AsbestosMuffins - 2025-01-22
great design, its got 2 lights, one for good, one for bad
@lmamakos - 2025-01-22
...and a power switch behind a closed door, operated only with a screwdriver. That tells you quite a bit, too!
@JimS-m1e - 2025-01-25
Until the "good" light burns out.
@lmaoroflcopter - 2025-02-02
@JimS-m1e i'd be more worried if the bad light burned out.