HP 5061A Atomic Clock Repair

[@AcornElectron]

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 😂

[@hypnotised-clover]

I think you're weird, I mean, you seem to be a sentient 1980s 8 bit micro computer.

[@marria01]

Cool username.

[@tekvax01]

right?! I love atomic clocks!

[@JarheadCrayonEater]

As a former Calibration Tech in the Marines (1999-2007) and for Lockheed at Stennis Space Center (2004-2012), I really appreciate this one! I spent most of my time in RF/Microwave, often calibrating Rubidium and crystal oscillators against our HP Cesium oscillator. Calculating the Allan variance and predicting the aging rate out to 6 months. I even wrote the custom GPIB application to automate the process. Thanks for this!

[@tekvax01]

Thank you for your clock service! :)

[@AsbestosMuffins]

great design, its got 2 lights, one for good, one for bad

[@PaulLoveless-Cincinnati]

Name one other person on this earth who can casually repair an ATOMIC CLOCK

[@azpcox]

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!!!

[@dereketnyre7156]

Cool - a new CuriousMarc video! Nice way to spend a cold dark winter evening - geeking out on HP equipment :)

[@tekvax01]

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! :)

[@AmiPurple]

Courageously snatched victory from the jaws of defeat, thank you for an enjoyable video.

[@nerdmeister2]

it‘s about time 😅 thank you!

[@who_let_me_on_the_internet]

Out of curiosity, did any HP atomic-clocks have an alarm and snooze function? Asking for a friend...

[@WOFFY-qc9te]

Maybe a socket to turn on a coffee percolator.

[@CuriousMarc]

Hahaha. Would be cool if they had an option for that!

[@douro20]

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.

[@CuriousMarc]

Even better, he got in touch with me and is helping me out. So he’s a gentleman and a scholar.

[@RichardFraser-y9t]

The sort of distraction I needed today.

[@Pamudder]

I remember reading about the 1971 experiment when its results were published.

[@CuriousMarc]

You are certified vintage!

[@were_all_fact6026]

Marc, he's fixing the real tick-tock! Din, Dan, Don.

[@SLeslie]

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.

[@lucasimark7992]

We live in marvellous times, don’t we… But let’s enjoy this marvel of engineering!

[@lor0the0fallen0angel]

Everyone needs a hobby, You know :-)

[@itsverygreen532]

Timely!

[@jbrown468]

ISWYDT 🤣

[@jtelliso]

0:20 I could use a yellow light to indicate that on me...

[@nigefoxx]

Stay tuned for the next episode? Both us and the clocks!

[@SusanPearce_H]

Time saver!

[@hymermobiler]

Your own version of saving Tik ToK nice!!

[@MikeWest_W]

What’s Marc mixing with his sanpellegrino? 17:40

[@CuriousMarc]

I drink it straight, don’t even spit out the bubbles.

[@lwilton]

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!

[@jameshackett9992]

Does a stronger beam current reduce the life of the big tube, did they change the transistor to increase the lifespan of the caesium tube ?

[@CuriousMarc]

No, it does not. The Cesium beam is actually neutral, and its rate is constant, only dependent on the temperature of the oven. The current comes from the electron multiplier in the detector, and is just proportional to the number of Cesium atoms you flipped. However, on earlier clocks, there was a setting to run the oven at a lower temperature to extend the life of the tube, at the expense of a less precise clock. Which is the exact opposite of what customers wanted! So on later clocks, the opposite happened. You had the option to request a high performance tube, that ran at higher temperature and had a shorter life.

[@yannickberrios]

Nice timing 😆

[@Brian-L]

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.

[@richardbrobeck2384]

I love the video !

[@MickOhrberg]

Do atomic clocks qualify for the PPM Tower (tm)?

[@CuriousMarc]

You bet!

[@timradde4328]

Who else owns an atomic clock. All step forward. No one? I know I don't. I don't even know how one works.

[@Albrecht_von_Preussen]

👍🏻👍🏻👍🏻

[@peterbjornx]

Nice work! I'm wondering if it'd be possible to do a Caesium-beam clock from scratch in the home machine shop - plenty of cool vacuum and physics projects are being done by amateurs already. By the way, Zeeman is pronounced something like "Zehman" (the ee sound is exactly like the vowel sound you use when you say the H in HP).

[@CuriousMarc]

You sure could if you were well equipped. That’s how the first clocks were made, in a lab. However the problem is financial. It requires ultra high vacuum, and UHVAC equipment gets expensive very quickly. Also Cesium is pretty dangerous to handle.

[@peterbjornx]

​@CuriousMarc I've already got quite a large amount of high vacuum parts as my reverse engineering hobby led to buying a SEM which led to more and more high vacuum tinkering :)

[@CuriousMarc]

@@peterbjornx Sweet! Then you are all set. Go for it! Don’t forget the safety squints when handling Cesium.

[@PaulLoveless-Cincinnati]

Also - I would appreciate an explanation of the entire stack used in this experiment. For instance, what is a distribution amplifier and why is it used in this setup? Thanks!

[@CuriousMarc]

Aha! You are ahead of me. Coming in the next video about the measurement setup. But briefly, the timers are used as dividers, and the distribution amp is used to double one of the 5 MHz clocks to 10 MHz and distribute it to the interval counter and the timers.

[@PaulLoveless-Cincinnati]

@CuriousMarc Thank you. This is absolutely fascinating content.

[@tintruder224]

Why does what direction the aircraft flew make a difference in their timekeeping?

[@c1ph3rpunk]

Why, one is flying into tomorrow while the other is flying into yesterday, eventually they meet at today.

[@ralfbaechle]

Due to earth rotation. In the one direction the plane 's speed adds to the rotation speed, in the other it is subtracted from the rotation speed Sadly this is incompatible with flat earth models which say earth doesn't rotate 😂

[@BradBo1140]

I thought 21:10 the exact same hingl

[@BradBo1140]

@ Thanks so much!

[@tintruder224]

@ralfbaechle so this change is relative only to the point on earth where a reference clock is located? Seems BOTH would still go slower, but at a difference related to the rotation of that point on earth. Thus a reference clock at the north pole would either show equal change, or zero if their location (east or west travel) remains equidistant from the pole?

[@MichaelEhling]

Really looking forward to your relativity experiment. How will you do it? (Surely HP and Mr Fancy Pants must have made a device to accelerate something to something like 0.42c, no? Darn.)

[@CuriousMarc]

We were thinking of the tall mountain experiment. Unless a viewer owns a jumbo jet and invites us in ;-).

[@justovision]

I would think keeping it as original as possible is important and not knowing much of anything about RF, could you insert a modern RF amplifier between the module and multiplier? Or even something different to generate the base frequency and replace that module or would impendence matching or something else make that difficult?

[@CuriousMarc]

You sure could. I thought of that as plan B, but since I managed to get it in spec anyhow, I did not have to go that route.

[@Rutherford_Inchworm_III]

Careful tinkering with quantum stuff, Marc. You might poke a hole in the space-time continuum and destroy the known universe. 🤭

[@CuriousMarc]

Oh that’s OK. I’ll just have to make a video on how I repaired the universe.

[@bunkermatty]

as always, CuriousMarc does things only dreamed of by the mentally insane 😝

[@jastrapper190]

If theory states that “time” is a relative quantity and it “slows down” when you’re close to any mass. Like as you approach a “black hole” or a point of infinite (or more likely just extreme density) your clock from an observer at a great distance would appear to freeze or stop. What if you had an observer that was at a great distance from ALL the mass in the entire (not just observable) Universe. Like everything that was in our universe was contained in a marble and another being was at a great distance from said marble and all the mass. How much faster could his clock be ticking? What is the difference between something surrounded by all the mass (even if we don’t know for sure this answer… how much mass is there beyond the observable) and another close to zero or none of the mass? It seems to me that a literal eternity might be zipping by out there… while our clock ticks but a single tock.

[@jaysonpida5379]

Always funny to hear, "problem with the tube ..." in 2025.

[@craigs5212]

Must be a nail biter working on something where one slip of the probe could bust the expensive physics package. What do you have to compare the two oscillators? A few years back I ended up with 2 Rb standards. I built a 10x multiplier so I could compare them on the scope at 100 Mhz. Some day I want to build a heterodyne difference counter from an article I have. Hard to measure things in 10 to the -12 range.

[@BlaMM74]

First view:) Love your channel!

[@lynzoido]

Just don't let these atoms escape!😂