HP 10638A Degausser: checking vintage HP equipment with more vintage HP equipment!

We over-test the over-engineered HP 10638A Degausser, in preparation for the tuning of the HP 5061A Cesium clock C-Field.
Video on how the Cesium atomic clock works: • How an Atomic Clock Re...
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[@radio655]

A precision cesium clock degausser: Always there is one more piece of test equipment of which you never thought that it existed and you definitely want in your collection.

[@rkan2]

Does HP (or Keysight) have a tool for all their numbers from 0 through 9999? :D

[@Adrian-foto]

@@rkan2 Just beware of HP overflow when model number reaches 9999 :D

[@rkan2]

Actually this tool was 5 numbers... so 99999?

[@TheGreatAtario]

Never thought I'd see a degausser that required calibration

[@leonerduk]

I love the increasing levels of "tools used to maintain other tools" going on here. Given as the Caesium Clock itself isn't the end goal, but it's the tool used to perform some other work, there's at least four levels in this one. ;)

[@coertlangkemper8862]

Oh boy, the final (far) digits of precision conquering Earth's noisy fields. Take care giving the clock it's special degaussed shop shelf. Thank you Marc for again sharing HP engineering marvels.

[@qzorn4440]

There is another gold mine of vintage instrumentation and that is the old 1930s, 40s, 50s sci-fi movies sets. With all the background meters and recorders in the evil "it's alive it's alive" monster labs. Like the Leeds and Northrup 1952 Speedomax type G chart recorder used for charting temperature and George Burr, 1940s Instron machine was working with a new device called a 'strain gauge' 😎 thanks a lot great HP 10638a video!

[@SubTroppo]

My de-gaussing experience is sitting over-night in a shack on the coast of northern England and measuring the tide-affected underground water level at the site of a proposed de-gaussing dock. Between measurements I killed time by removing the tannin accumulation from the insides of the tea-mugs (a major task).

[@DiverCTH]

Thank goodness you didn't get to the teapot. I've heard those accumulations are strong enough to chip carbide-tipped screwdrivers

[@SubTroppo]

@@DiverCTH I don't think that the shack ran to a teapot; strictly teabags.

[@DiverCTH]

@@SubTroppo Assuming this is a "lost in the pond" moment. I was borrowing from the late Sir Terry Pratchett's Sam Vimes novels and assumed there's a British version of the bulk pot that American drip coffeemakers use. We yanks live on coffee instead of tea, and depending on the setting, the pot either gets left to boil dry or is reused for long periods between washings (a quick rinse doesn't count). The truely ancient metal-bowl pots can accumulate an unbreakable .5mm crust of burnt coffee whereas the modern glass or plexiglass ones break before that happens.

[@SubTroppo]

@@DiverCTH Domestic teapots are never cleaned out but I am not sure about tea-urns which used to be used in factory canteens etc. I tried a Terry Pratchett book but just couldn't see what my brother was going on about. However the first two books of the "Gormenghast" trilogy by Mervyn Peake are an entirely different matter. To paraphrase Star Trek: It's coffee Jim, but not as we know it here in Australia. ps The Yanks used to drink tea big time, why else the 'Boston Tea Party"? pps I hear that Americans are getting around to electric kettles!

[@kaitlyn__L]

@@SubTroppo I know plenty of people who wash their tea pot by hand every few weeks, some, even stick it in the dishwasher occasionally. The only reason not to do it is if you only have one teapot!

[@video99couk]

4:02 My tape degausser has a conveyor belt, it looks like a supermarket checkout. You can drop any kinds of (oxide) tapes on it and they fall off the end, blanked. It's less effective on metal formulation tapes though, they have much higher magnetic retentivity (one reason that Video8 is better than VHSC). It's seriously heavy.

[@EricLikness]

Applause 👏 on using the period correct 2-pen chart recorder for full effect. The right tool for the right job.

[@MarcoTedaldi]

When curious marc posts it's always worth to watch. Came for the AGC back than and stayed for all the cool stuff!

[@eeengineer8851]

Long ago played with a degaussing coil on color TVs. I think the one in the shop was home-made even. A few years later I was dumb and put a neodymium magnet up by a CRT monitor. OOPS with a colored spot that did not go away on a power cycle (so the degauss circuit in the monitor could fix it). I recall flipping the magnet end for end and carefully doing hand motions around the spot to work it away... Then there was the time I had to work with a permanent magnetizer. It was for magnetizing flywheel magnets on small engines for the ignition. It came with a gauss meter and you had to have a coil to slowly draw the magnet through to measure the field. I made one (from the manual info) out of normal wire and got to practice trying to measure when the magnets had reached max strength as determined by how many volts on the big capacitor bank got dumped into the winding on the fixture. A real "thump" piece of gear!!! Fun times!

[@kaitlyn__L]

I once did something similar, except instead of massaging it away manually, I just waited for it to slowly go away over about 30 power cycles with regular use. Luckily, it was just my TV in the bedroom (which itself was just an older TV from the living room) so no one else was bothered.

[@KeritechElectronics]

Mighty exotic gear indeed. Love the plots! That magnetic tape degausser reminds me of Techmoan :)

[@revenevan11]

Really fascinating old school stuff! Somehow I get a kick out of it being HP hardware too, used for a historic experiment (the relativistic time dilation measurement). I love the intersection in history between analogue and digital, and when you add in this level of precision it's even better!

[@edgeeffect]

That chart recorder IS lovely!!

[@terrygains8327]

If you are planning to replicate the Flying Clocks' Experiment and Fly one of the HP 5061A Cesium clocks and compare to the time on the HP 5061A Cesium clock left on the ground, I'm happy to chip in for the air fare. :) Bonus points for historical accuracy if you can do with a DC-7 aircraft per original experiment, but whatever you do, it's always a fantastic video. Thank you.

[@Damien.D]

I think they have all the hardware and knowledge to fire-up an unused Saturn V and do this experiment by landing a clock on the Moon.

[@markevans2294]

There are currently no airworthy DC-7s. Possibly an airline, or Boeing, would agree to carry one on a test flight.

[@thebiggerbyte5991]

I'd love to see the HP brand back on top scientific equipment and not on mediocre consumer stuff, but equally good is CuriousMarc's collection being put to use. Love it.

[@thesteelrodent1796]

Ever since Compaq drove HP into the ground the name doesn't exactly command respect anymore, so even if HP and Keysight were to get back together it'd likely be bad for business to put HP on the equipment. To anyone who don't know what HP was before they got slaughtered in 1994 it's a brand that for the most part signals low quality and overpriced. It's sad that their server tape drives are the only thing they're good at these days, and occasionally they make a laptop that's not a total ripoff, but that literally is the state of what remains of the company now

[@thebiggerbyte5991]

@@thesteelrodent1796 agreed, but I can dream :). That said, their workstations are pretty good - I love my old Z800.

[@plumbr13]

I like my HP laptop. It's well-designed and reliable.

[@zh84]

Ah, the offset null pin! That takes me back to my school days and learning about the 741. Using the offset null was one of the exercises in the book.

[@c1ph3rpunk]

I’ve been in withdrawals without a video from y’all.

[@thomask6295]

Nice to see that someone still has an HP 180A oscilloscope in use. Mine is in storage. I'll have to get it back to the lab sometime. It was my second oscilloscope after the HP 175A monster.

[@williamsquires3070]

(@4:49) I hope that wasn’t the only backup copy of Minesweeper for the PDP-11! 😆

[@benjaminhanke79]

That's probably how the moon landing tapes were overwritten.

[@testing2517]

"We can make it perfect." "It's within spec." "Ok, it's within spec! Leave it!" Engineers... :)

[@Debraj1978]

My childhood TV always used to hum during start (with ocassional flicker of house lamps). And that is degaussing, the brute force method.

[@RogerBarraud]

Yayyy! Another video from CuriousMarc! I was craving my retrofixit fix! :-)

[@AppliedCryogenics]

Marcel's a protective father of his vintage electromagnetic baby.

[@GodOfMetal1991]

i worked with a table mount demagnetiser at work, do demag metal stuff that was grinded with a magnet table. Now I understand why pulling it slowly away while the thing was running make the best results. love your videos, learning new things every time. :)

[@Romulustj]

What a great way to end my night! :D

[@alexmaurer]

So much fun with this plotter 😃😃😃😃

[@tekvax01]

very cool guys!

[@phomchick]

Wow, Marc, a Han-D-Mag! I’ve had mine for close to forty years!

[@EvertvanIngen]

This makes me happy

[@michaelmiller641]

Fascinating!

[@thesteelrodent1796]

4:44 having the tape degausser between the tape drives seems rather risky. Wouldn't want to mix them up :D

[@keitha.9788]

HP 10638A - The perfect Christmas gift for the engineer who has everything.......................

[@624Dudley]

Good stuff. 👍

[@FrancSchiphorst]

Pretty sure at some point an infinite loop of equipment needed to tune equipment will be created causing endless what came first the chicken or the egg like discussions :)

[@joswhite7923]

Excellent!

[@ReneSchickbauer]

Much easier when you have to recalibrate your modern voltmeter. You just take any old Apollo equipment and use its power supply as a precision reference ;-)

[@_2N2222]

Demagnetization with very low frequencies makes sense and may be even required. Depending on the circumstances, magnetic fields produced with mains currents of 50Hz or 60Hz may appear as of "high frequency" to the magnetic material. This will cause eddy currents in the surface of the material, which in turn shield the inner parts of the material from the applied field, so the demagnetizing field cannot penetrate the entire material. At lower frequencies, the demagnetizing field goes deeper into the material and has a stronger effect.

[@erikdenhouter]

Good point in this respect: I learned in the '70 from a Japanese technician from Akai (Mr. Nakamura) how to de-magnetise audio recorder heads. Of course a 50Hz coil was used, but when he pulled the split of the coil slowly away from the playback or recorder head, he also described small horizontal circles with his hand, so the field was also pulsing in a sort of 1 Hz amplitude until his hand was behind his back.

[@68hoffman]

wow...that was kool to see ..i never knew they blanked out those data tapes ..i guess to make sure the data on there could not be used by others ...such a great collection..all can still be used today for real science ..that is the seal of quality :)

[@SeanBZA]

Not to make sure the data was gone, but to leave the blank tape so that it could be re used, and not worry about getting bleed through of old bits that the record head did not flip correctly. You want to record ideally on a neutral bias, so the head current is low, so it will provide enough energy to flip all the way one way or the other, if you have old data there your head either has to have a higher current to ensure it can flip from one to the other, which heats up the head unnecessarily, and also runs the risk of the stray field flipping other bits already recorded.

[@CuriousMarc]

I think it was primarily used for instrumentation tapes, as instrumentation recorders did not always have erase heads. Use for data tapes required a hub adapter accessory, which you see I hastily cobbled together.

[@bennylloyd-willner9667]

@@SeanBZA I know what you mean, but I found it funny (weird humour, I know😁) that what you described was actually precisely "making sure data is gone", just not for the "spy" reason 😁

[@RingingResonance]

12:44 you draw my profile picture!

[@Brian-L]

Where does he get all these wonderful toys? Looking forward to the next episode!

[@CuriousMarc]

- degausser: eBay (Marcel got it) - timer counter: viewer donation at VCF - DVM: eBay - chart recorder: - long sought after elusive main machine: test equipment auction - elusive pens: eBay - elusive graph paper: viewer donation - manual: eBay + a lot of work to revive that one!

[@ThomasGabrielsen]

I would like to have that plot on the wall.

[@soulrobotics]

I would like to see a battle between Marc's HP instruments against the new Keysight... by category... Let's see if they continue to uphold their slogan "Keysight works with innovators..."

[@tim_bbq1008]

I'd love to see the HP equipment used to check calibration of the Keysight equipment

[@tbp-channel8870]

Hello Marc, maybe Off-Topic a little bit.. I would love to hear a "before and after" comparison, if you would put a normal recorded quarter-inch audio tape into the 3603A. Would there be hearable artefacts, like print-through, and at how much dB S/N ? Possible ? Anyway.. nice video, as always !

[@lerk.]

I only know degaussing from the button of my old monitor that engages disco mode.

[@Muonium1]

Looks just like a free induction decay signal from a nuclear magnetic resonance machine as the nuclear spin precession relaxes back to the ground state.

[@624Dudley]

That.

[@mohaaabdi262]

i wonder if you could share a link of the book that you are using if you have it a as soft copy

[@miked4377]

your hp equipment is the best and most interesting thing on the channel...

[@douro20]

Could this be one of the rarest pieces of equipment HP sold?

[@j7gy8b]

I can't wait to see the quantum experiment that helps you calibrate a clock!

[@laurensvisser7623]

Hewlett-Packard. Degaussed to Perfection ©

[@bin_chicken80]

Can you put a modern mechanical hard drive in the degausser to see if there is any data left? I know it's not made for that but maybe you could try it if it somehow fits? Thanks!

[@thesteelrodent1796]

hard drives require a stronger magnetic field than tapes - because the alloy shell helps shield against magnetic fields - so it likely wouldn't be very effective to stick a harddrive in a tape degausser

[@bin_chicken80]

@@thesteelrodent1796 Thanks for the response. We still don't have any scientific evidence of this :P If they have the time to try, It would be interesting to see :)

[@benjaminhanke79]

That hard drive would be very dead, if it's affected by the degausser at all. The disc contains tracks that are essential to make the head control circuit work.

[@stargazer7644]

This degausser wouldn't even touch a mechanical hard drive, or even a modern tape cartridge for that matter. Their high density formulations require far, far stronger fields than this unit can produce.

[@tschak909]

that is....an epic....cycle............time........

[@OscarSommerbo]

A HP operation on HP equipment requiring more HP equipment, I am not saying it is a scam, or that it doesn't work, but the feedback loop of expensive HP only equipment is... suggestive.

[@lmamakos]

The pursuit of precision time and frequency is fraught with exotic challenges and opportunities.

[@platin2148]

Dang did i see a emco there?

[@CuriousMarc]

Super 11 CD. Good eye!

[@dentakuweb]

Big Clive did a simple video about degaussing a few years ago. kzbin.info/www/bejne/bmK5ppubYt6nsJY I took a transformer from a lamp and rearranged the laminations to turn it into an e-core electromagnet, put it in a box with a momentary button and a giant LED to show when it's on which works fine to demagnetize pliers, cutters etc. You just have to pull the tool away from the magnet slowly. Of course I can't pull them away in a perfect exponential curve over 22 minutes. :)

[@Wombbatts]

I leveled up Nerd watching this. )

[@rallymax2]

Ooooo degaussing Monday.

[@marvintpandroid2213]

I feel the planetary fields unaline

[@nandi123]

What became of your HP 21MX?

[@CuriousMarc]

Still there. Two of them now. Got displaced in the queue by the Apollo stuff…

[@nandi123]

@@CuriousMarc Wonderful! 🙂

[@LaurentLaborde]

I heard you liked HP so I put HP into your HP ^^

[@geoffreykeane4072]

Sigh. 1960s HP gear working to perfection. Yesterday me trying to get an elderly neighbour’s brand new HP inkjet printer to work. After two hours - Nope. Returned for another brand that “just worked”.

[@ErulianADRaghath]

I spy some White Crane sake on your table :D

[@CuriousMarc]

It’s the water bottle for the soldering iron sponge. But it was sake once,..

[@thechefkoch123]

The 3603A is not really emc compliant

[@soulrobotics]

Damn!. Now I want to have a degauser in my instrument collection without use

[@gordon8657]

I have no idea how you find this obscure equipment. There couldn't have been but a few of these made

[@TrimeshSZ]

They were not that uncommon - basically, if you had a 5061 with a high performance tube you had the degausser, simply because the use of the degausser was required to meet the stated spec. You had to use them quite frequently, too - if you moved the clock any significant amount you had to do a high-current cycle, and you were supposed to do a low current cycle if you just turned the power off and back on again. At this point, I expect there are likely more degaussers than functional high-performance tubes, simply because to get stated performance you basically have to run the clock 24/7 and in that state it only lasts about 8 years before the beam current drops to the point where it starts to degrade the tube performance. This is also why a lot of these clocks were taken out of service - if the tube started to get weak, then it made sense to replace them with the HP5071 because the standard tube on the 5071 provided better performance than the high-performance option on the 5061 and lasted a lot longer.

[@lineways5477]

Degaussed my 100 BTC hard drive 🥲

[@acmefixer1]

I just wonder how much this C field affects the cesium beam and the time. Should we be concerned that all those cesium beam clocks out there are a bit off because they haven't been degaussed in years? Or what? 🤷🤷 Thanks for the entertainment, Marc!

[@ShainAndrews]

They operate within spec or they don't.

[@TrimeshSZ]

No, the effect is pretty marginal - IIRC, the standard tube was quoted as 1 part in to 10^-11 and the high performance tube was 7 parts in 10^-12 - the degaussing is not considered necessary on the standard tube because it will hit the specs without it. Also note that in a lot of cases the reason people used the high performance tube was not so much the better accuracy but the improved close-in phase noise (standard was -80dBc/Hz @ 1Hz, and opt 04 was -100dBc/Hz @ 1Hz) - the downside is that it burns through the Cs a lot quicker. Another thing to remember is that the 5060/5061 are basically museum pieces now - even the (30 year old) HP5071A doesn't need degaussing for full specified performance.

[@absolutely1337]

I have been wondering what exactly a degausser is all last week! Zoomers don’t know the fun of magnetizing mommas crtv was as a kid!

[@profpep]

Or the not so much fun TV repairmen had getting it demagnetised again. The degauss coils in the set would only go so far, and if a kid had magnetised the shadowmask with a powerful it meant getting out the really big degaus coil. I worked at Thorn Colour Tubes in the UK as a student, and remember the wonderful patterns we got with the big degauss coil on setting up brand new tubes for QA

[@AsbestosMuffins]

yey

[@bigsarge2085]

✌️

[@cdrom1070]

every time I hear over engineered I think 'try working a few days in a lab and get back to me'.

[@absolutely1337]

During ww2 they would degauss ships as to not attract magnetic mines at sea. Cool shat, eh?

[@MrArgon39]

Where sound?

[@philstephes]

Glad to know it's not just me

[@cormacmccreary9160]

It's youtubes stupid compression algorithm, give it an hour and it should be fine

[@philstephes]

working fine after a reload

[@ShainAndrews]

You need to learn patience.