Apollo Comms Part 4: Transponder power up preparation, and more original equipment found.

[@72polara]

Getting your hands on rare electronics is one thing, getting the test fixture is a whole other world!

[@RetroSwim]

This holiday season's most anticipated series can't be found on Netflix or Hulu, it's right here! Seriously on the edge of my seat, guys! Great work!

[@SpinStar1956]

For most people, all they'll see are some rocket-hulls, space suits, command module and to them, that was the space program. Curious Marc and his talented team are taking us into the bowels of what made this incredible feat possible. When you think about it, there lie thousands of stories just like this one, within all the technical systems and subsystems that comprised Apollo. That is why it is so sad that most of the equipment (test and support etc.) has been relegated to the scrap-heap but without which, NO one could have gone anywhere let-alone the moon. In other words, all these systems represent a technical 'Master-Class' in each of their fields. So, we must curate the technical side of our history, before our society relegates this historical feat to that of myth...

[@MrHichammohsen1]

Yes finally another part of this amazing series! Thank you Marc.

[@nesagljivic]

Mark , your reverse engineering , debugging , resurrecting from the dead is epic! Great joy to watch , and also happy to see youngsters getting involved in it. The world might not be doomed by collective amnesia of our past.

[@Aengus42]

Fascinating series! I wish I could smell these beautiful systems as they wake up & shrug their half century if sleep off of themselves. There's something very special about the scent of old, warm electronics.

[@MeriaDuck]

15:15 holy canary that's a decent amount of holy grails for a project like this, awesome.

[@Vl7248]

I love these videos! Incredible that so much technology was developed to deliver incredible telemetry in the 1960s!!

[@TechGorilla1987]

@18:06 - "OH! LIGHTS!" That is perhaps the most animated that I have ever heard that gentleman, so I absolutely know this is an exciting breakthrough! :D

[@mikestewart8928]

Usually for initial power-ons I'm in my "flight controller" mode -- stay focused and observant, and celebrate later. This time I wasn't, and was kind of caught off guard by the thing just immediately lighting up. :)

[@TechGorilla1987]

@@mikestewart8928 You're certainly an interesting character and the three (or more) of you together is like a walking research laboratory. Good stuff.

[@FesixGermany]

Superbrain Mike is back

[@vincei4252]

Been in the industry for years. I'd kill to work with engineers like Marc and Mike. Top notch.

[@DK640OBrianYT]

An incredibly interesting workload you have put onto yourselves there. Isn't it funny though, that I have no doubt at all, as in 0.00%, that you'll succeed in making this stunning beauty working again. Absolutely no doubt. What are you feeding your brains with along the way ? Pizzas ? Homemade cooking ? Burgers ? It would be highly interesting to see how the powersupplies works in terms of delivering stable and clean voltages without any jitter or other "misfortunes". Scope please. Carry on good men. Cheerioh from Denmark Scandinavia.

[@MatzeMaulwurf]

No brain food needed. They wear the fancy pants all the time! 🤓👖

[@CuriousMarc]

Part of the tradition, besides the fancy pants, is that the whole team always goes out for a long lunch at a nice local restaurant. You got it right, got to feed your brain and take big breaks, or we’d go bonkers (or more bonkers than we already are).

[@gerryjamesedwards1227]

I love this electronic archaeology!

[@TomKristiansen]

This is so cool, i think they wants to rebuild the Capsule at the end.

[@ricod9451]

If Steve Jurvetson has one in his amazing collection, they sure will !

[@pjbth]

I think they'd rather rebuild the test lab, but I think the original might already be at Steve's house.

[@AsbestosMuffins]

the only problem is there's like 2 surviving command+service module stacks, and the capsules themselves are in varying states of completeness since they did tear them apart afterwards for inspection

[@stheil]

@@AsbestosMuffins yeah but the same can be said about most of the stuff these guys have already got working XD

[@TheOnlyDamien]

@@pjbth I have always wanted to see one of those kinds of labs/station areas rebuilt entirely, the crew here is so great I love these videos. And Steve of course for being so into it to let them do all this work.

[@whiskeytuesday]

This video really makes me feel better about the documentation I write for my code

[@bassybossy]

Always a joy to see Mike working his skills and talents along side you Marc! Always great to see the curious minds coming together :D

[@jtveg]

What great luck getting that bit of original test equipment. I can't wait for the next episode. Thanks for sharing. 😉👌🏻

[@pedro_mg]

would be cool a small episode on Mike, his work, his projects. Mike fans unite :D

[@jurvetson]

Bountiful Thanks giving! Power up seems imminent!!! And I love the shade of blue hidden in these lighting systems

[@eduardocarvalho1547]

Those last seconds in the video is like candy, I'm waiting for next part!

[@acmefixer1]

At the end, it looks like you're well on your way to making the next episode. Thanks!

[@MCCRITTERS]

Lest have a huge Kudos' to those who had the foresight and ability to preserve this historic equipment and our current heros that are bringing it back to life!

[@GeeWillikersMan]

You should get in touch with the Motorola museum. Who knows, they may have photos or schematics or more of its history.

[@GrantWyness]

What is it about this channel that draws me like none other…

[@kevinreardon2558]

This is so cool. I grew up when these were brand new. Us little humans were quite smart back then.

[@nanieas]

Fascinating. I hope the modifications to the schematics are documented.

[@soniclab-cnc]

all day I had this cued up to watch.... after a long day I finally get to sit and watch my favorite nerds play with space junk.

[@CuriousMarc]

We play, it's space - but it's not junk! ;-)

[@soniclab-cnc]

@@CuriousMarc it is so very cool ! Can't wait to see some signal pass though it now its powered on... and still in spec after 50 years! (mind blown)

[@rsmrsm2000]

you should provide high resolution photos of the equipment.

[@MarcelHuguenin]

Wow, top job guys! Can't wait for the next one!

[@krnlg]

This series is just so frigging cool! :)

[@FrancSchiphorst]

Could the drawer be just that, a drawer to put all the needed cables and test harnesses? It uses some very specific cables so i doubt they will be used elsewhere so might as well keep them very close by :)

[@SpinStar1956]

Usually if it is meant for storage, the drawer will have bottom (I did not see one). Also, if it is storage, there is a protective panel just in back of the front-panel to protect the front-panel components. It also looks like the transponder would be too large for the drawer and make it past the connector. since I think it is a 19 inch rack. But my thinking was along with yours, in why wasn't that connector on the front of the panel.

[@zyeborm]

@@SpinStar1956 Do have to keep in mind that this is likely the 15'th time this test panel has been hacked on, it would have been changed during development, then probably more changes through the missions. Then who knows what it was used for after apollo.

[@daviddavidson1372]

Love this series of videos. I have one of those receiver's you have stack beside the one your working with in this video. Mine has damage just to the center tune meter. Easy fix. But mine has a small metal tag under the attenuator knob that saids Cm Fm and has the frequency .can't remember frequency right now. Talk to bill woods on collect space. He was in charge of s-band communications during the appolo missions. He said those receivers would have been used for Nasa vendors for testing of the command module transmitters. Love seeing more of this equipment. You guys can figure out anything.

[@chupathingy5862]

On this Thanksgiving, I'm thankful for CuriousMarc's contribution to the archival of world history.

[@maicod]

you guys leave me glued to the screen !

[@Dennis-uc2gm]

If you had an extra mating connector(s) a break out box could be made for easier testing and continuity . I used them a lot when I used to work for a defense contractor, they could be very helpful and easier to use than trying to get right on the pins with test probes. Over the years I've read a lot about the Apollo communication system and design so I find this fascinating that your bringing this back to life.

[@SeanBZA]

Those are standard avionics connectors, so you can buy them new from companies like RS, and for this very likely that if they reached out to a company or three in the avionics business they probably would get a box of the various types given to them. Got to be some viewers here in those companies, and they probably have bins of obsolete style or configuration connectors, which are worth using just for the pin packs alone, let alone the backshell.

[@johnedwards1685]

That 41-way is a connector my workplace used for a good long time. Its made by Amphenol and comes in a variety of backshells and cable clamps. Sometimes specific Amphenol connectors can be suddenly very scarce for some reason. What worries me is the other connector on that casing. It looks to me to be a Reynolds HT connector. The white supplying leads will be Reynolds PTFE HT 15kV+ bonded and potted in. I take it that since the conductors on that connector are female it is the supply side. When the power supply is activated there may be 10 - 15kV present on conductors in that socket and it will flash over to deck and/or an adjacent pin without the mating connector fitted. A dangerous potential hazard.

[@peakinout1]

Very cool Soviet rocket lamp dude ! have one my self .Keep up the good work.

[@ericblenner-hassett3945]

Check if Case Ground is shared with the Capital A pin!! I have seen old ( helped part out a 1950s ) stove and the wiring had the ceramic coated case as earth ground. One reason it was getting scrapped was the chance of shorting out the cook due to corrosion.

[@swedenfrommycam]

Sooo Amazing to watch u guys! Thanks a bunch! Can u do a walkaround in the cave to show all your cool stuf? Keep up the Beautiful show!! 🇸🇪👍

[@bennock1017]

fantastic, great job all.

[@rpavlik1]

Impressive, and the "found" control panels are lovely. More of those pretty roto-tellites! (Iirc)

[@pdppanelman5889]

And as we travel back in time to the late 1960's we now see how the impossible was done. I never thought I would see this.

[@russmiddleton5486]

THe Transponder Mount does have a STE label stuck to it so pretty good bet it's test equipment.

[@prt1527]

What does STE stands for ?

[@russmiddleton5486]

@@prt1527 System Test Equipment

[@mikestewart8928]

@@russmiddleton5486 ​ It's actually "Special Test Equipment", apparently. We thought it was System Test Equipment too, at first.

[@russmiddleton5486]

@@mikestewart8928 It's System where I work. But it could also be Special... It might work it we spoke nicely to it.

[@russmiddleton5486]

@@mikestewart8928 There's always room for a duplicate acronym :-)

[@kriss1_]

I think i'm gonna need the next episode right now

[@chrisdickens4862]

Beautiful!

[@bborkzilla]

Actually, for three phase WYE configuration, you do have a neutral. For Delta configuration you do not. They may have changed their minds on which configuration to use.

[@SeanBZA]

Most avionics will only use delta connection, the neutral is not normally used, more often provided as instead a protective ground connection to keep the fault current from a failed transformer from flowing through the circuit chassis, and creating more failures there. If you need a wye connection you will always find a separate 3 phase transformer used, with the secondary providing the wye voltages and neutral, typically 28 VAC and 5VAC, used to power smaller synchos and other magnetic instrumentation and calculation, and the 5VAC is normally used to provide the 400Hz reference clock to electronics, typically with it being either an integrator to recover the peak, by detecting the zero crossing, or having a simple diode rectifier, and then a comparator detect it rising to near the peak. The signal is then used to drive sample gates on the other AC inputs, with the voltage captured in the sample window giving the angle of turn of the input, or whatever the particular synchro is sending. Everything locked to the 400Hz clock, so even if it drifts the readings stay absolutely steady. In the era this was made all those sample gates would be junction FET's, driven with -15V gate drive, with the input signals being scaled to 5VAC, either with resistors or transformers, or direct from the synchro units. Even variable resistor units would be powered with the 5VAC supply, so that all noise is removed from the reading. With the ADC units of the day you could get a very stable 12 bit reading out of the signal, with the odd 1 lsb flip every few seconds.

[@scowell]

Happy Thanksgiving.... you found the GSE! Gets easier from here.

[@marvintpandroid2213]

Ground control to Major Marc....

[@kurtnowak8895]

I was gonna say, that drawer was likely the storage for the breakout cable,

[@twilliamson3]

This stuff is so cool.

[@larry785]

I have some used cannon connectors if you need any for the project.

[@jantonkens9820]

Can't wait for power up. Maybe you can retransmit moon landing videos and this time stream that live. Maybe ask SpaceX to install repaired unit in the moon landing "ship" as "proven technology"..😁

[@soulrobotics]

I also have my bottle of "S. Pellegrino" in my workbench... Amazing Job Marc!, nice to see Mike around... I am wondering if he will reduce all that electronics into a DEO-NANO kit.

[@rrostagni]

Captivant, merci !

[@knallertk8062]

good job

[@CodeAsm]

This is so awesome :D good luck guys.

[@feicodeboer]

Is there a launch date planned yet?

[@VorpalGun]

If you have the pins, couldn't you 3D print the connectors if they are that expensive?

[@BittyDaProto]

To the moon!

[@liquidsonly]

And beyond!

[@LostAgain1970]

I prefer this kind of electrnics so much more than today's miniaturized surface-mounted components. Dunno why? But this kind of electronics makes me happy.

[@prt1527]

Very nice job as usual ! But what are you going to broadcast when it'll be up ?

[@CuriousMarc]

We're planning to send Carl to the Moon. He's already moved close to Cape Canaveral so he can sneak in when ready.

[@carlclaunch793]

@@CuriousMarc The only way to accurately test the ranging detection hardware is to take a transponder to a known distant point. I volunteered at once.

[@GeneralJackRipper]

Are the differences between the hardware and schematics related to the fact you have an engineering test unit and not a flight unit, or is some variance between schematics and hardware normally encountered?

[@ostrov11]

Спасибо за контент.

[@rsmrsm2000]

Amazing !!!

[@MLX1401]

"The nightmare before Christmas, but it's Schematics" -episode

[@ruadeil_zabelin]

19:36 Final Fantasy 14 music ey? Nice

[@CanDoo321]

Awesome

[@pulesjet]

Some of that Looks like the stuff I worked on in the USAF DAYS.

[@bradwilmot5066]

Stupid question time... Unless I missed something, A13 lost both AC buses when they lost main bus B totally and had a pretty good undervolt on A. If the XPDR requires AC, why did A13 not lose USB capability? (or did they not lose all AC, and I'm remembering wrong?)

[@michaelmiller641]

Interesting!

[@techalyzer]

Question - are these the actual electronics used on the mission or just replicas, like a copy of the same thing?

[@thesteelrodent1796]

When you go "the diagram is wrong" I immediately thought "what if the diagram is right and your device is wired wrong?"

[@NixToDo]

There are pins shown twice in the diagram. So, the diagram is wrong.

[@mikestewart8928]

Future Mike here. It's a bit of both, I think, depending on how you look at it. Aside from the obvious errors like the same pin being used twice, I think there's a good chance a lot of the "mistakes" are, as Marc speculates in the video, because this document may have been made for a slightly different iteration of the transponder. I just recently acquired a slightly earlier set of the schematics we're referencing, and they're even more "wrong" -- including using separate coax connectors for everything instead of the one big hex coax one. It seems pretty likely that the design was still in work when these schematics were drawn up. Also: of the 44 pins on that connector, at least 22 -- half! -- were wrong. :)

[@gth042]

@@mikestewart8928 My vote's still you got the schematic we leaked to the rooskies. Hope you guys have been well.

[@dieterschaub8765]

@@NixToDo But they insist, they make it to the moon?

[@AndreaThing]

​@@dieterschaub8765 I can assure you from first hand experience that all complex engineering endeavours are like this: lot of documentation revision. This means that eventually all non final versions of the doc are somewhat "wrong", but doesn't imply the final product is wrong in any shape or form.

[@SoddingaboutSi]

Is the 120V 400Hz ? Aircraft use 115 V Line to neutral. Concorde used 1Khz apparently

[@Chiavaccio]

👏👏👏👏👍

"So, we have finally rebuilt the whole Apollo program, and are preparing for launch to have nice views from lunar orbit as Artemis I arrives..."

[@electronash]

This was great, as always. Super nerdy pinout stuff, but that's why most of us are here. :p Were most of the circular connectors still made by companies like Amphenol back then, or a few different companies?

[@mikestewart8928]

Almost all of these are from Deutsch, which has since become a part of TE.

[@electronash]

16:26 Could possibly be a drawer for testing only one sub-module from the transponder, maybe with a heating plate involved? ie. not as much airflow in there, to keep the temperature of the DUT a bit more stable?

[@electronash]

I found a reference to "USBE" in a paper from GE Astro Space, which also has an article about Motorola.

[@electronash]

Ohh. USBE = Unified S-Band Equipment, ie. the long-winded NASA name for the transponder itself. lol There's a page on spaceaholic about the transponder.

[@electronash]

Also a PDF titled "APOLLO UNIFIED S-BAND - NASA Technical Reports Server", mostly block diagrams. But I'm sure Mike probably has most of the docs already. Ooh, "APOLLO UNIFIED S-BAND - NASA Technical Reports Server" is very interesting. Tons of info, mostly about the ground station equipment, with photos of some of the rack units. (19650025875.pdf)

[@cambridgemart2075]

The use of an AC supply is rather intriguing; whilst I know that aircraft (and most military equipment) use 115V / 400hz (208V if 3 phases), that's because all the vehicles have rotating engines of some sort, so driving an alternator is an obvious choice for generating electrical power. Given that there are no rotating engines in the Apollo, all electrical power is generated as DC from the fuel cells, so converting to AC is a lossy process.

[@bobl78]

what´s the reason for the strange 120V 400Hz ? Why 400

[@CuriousMarc]

This is actually standard avionics power. 400Hz makes the transformers smaller and lighter, hence the use in aerospace.

[@michaelsouth2567]

"Pin *lowercase* s". Implying there's an uppercase S too? If I was an assembly tech, that would be very... anxiety-invoking.

[@mikestewart8928]

Yep! Even worse, on the connector it's uppercase and lowercase. But on the schematics, they're all uppercase, and the letters that are supposed to be lowercase are instead underlined. It keeps you on your toes.

[@SteveVanDeBogart]

Drawer is probably for all the cables.

[@randycarter2001]

You technically don't need a neutral on 3 phase. For every amp going in on phase A there is a 1/2 amp leaving on phase B and C. Where was the 400Hz AC coming from? Fuel cells and batteries only provide DC.

[@Bata.andrei]

A rotary inverter unit...i think they were quite common in aeronautics before solid state ones.

[@randycarter2001]

@@Bata.andrei I'm surprised they sacrificed the weight. For every pound of weight that went to the moon it took 4 pounds of fuel to get it there.

[@guywilkinson]

But what kind of batteries did they have back then? Not like today 🤔

[@acmefixer1]

@@guywilkinson Spacecraft often used Eagle Picher batteries with the electrolyte separate. When the system was activated, a charge would go off and shoot the electrolyte into the battery.

[@dale116dot7]

@@Bata.andrei I thought this spacecraft used a thyristor inverter, it was synchronized to the AGC’s oscillator.

[@theposguy1435]

How do make the 400hz ac?

[@carlclaunch793]

There were inverters on the spacecraft to convert the fuel cell or battery supplied 28V DC to 3 phase AC. Most efficient way to power the various motors, such as fans and pumps.

[@randomunavailable]

CuriousMarc and team attempting to restart the Apollo program all by themselves.

[@kippie80]

I'd herd it said that the Apollo mission was the finest achievent of Russian counter intellegence. I thought that was pretty funny. Scare those yanks out of their capitalist bickering enough to actually achieve something.

[@trcostan]

Looked like some nice RF stuff in that test set! Variable attenuators maybe?

[@mikestewart8928]

Those are "double slug tuners" -- specifically the SF-30N. We do think they're essentially being used as attenuators here, though... right Marc?

[@CuriousMarc]

I think they are used as variable phase reflection simulators, to test transmitter stability. There is also a directional coupler that is used as a tap off for the output, or an attenuator if you will. Finally there is a dummy load at the end of the main line.

[@physnoct]

And flerfs say we lost the technology? Nah! It's so much documented that your team could rebuild it (... "we have the technology").

[@nahuelolgiati5969]

WOoooOOwoow

[@benjaminhanke79]

It's a big face. The open drawer is the mouth, two black eye knobs and the brains light up.

[@Bierkameel]

I want to see someone at NASA freak-out when you power that thing up.

[@eugenioarpayoglou]

These videos are too short!

[@patrickradcliffe3837]

No pinout diagram for the cannon plug?

[@CuriousMarc]

All the docs on our websites. Links in the description. Sometimes it takes me a little while before I can update the page when new material is added, but in this case it's already up. Let me know if you can't find it.

[@pulesjet]

Well it would seem NASA complicated the hell out all the simple things we had to work with?

[@Spookieham]

I'd argue it is in fact a beautifully designed and engineered piece of equipment with lots of redundancy.

[@pulesjet]

@@Spookieham I find it amazing that they accomplished what they did with what they had to work with. The whole craft was wrought with redundancies to insure the mission had a chance to succeed.

[@kevinbarry71]

For anybody who thought analog communications was simpler.