Apollo Comms Part 29: Downvoice

We back out the last remaining modification from our NASA receiver and return it to its original Apollo voice channel. If we are successful, we'll get to hear the voice from the astronauts the exact same way it was transmitted during the missions. And I hopelessly butchered the name of our hero engineer that left the helpful notes on the equipment, it's Frank Landspurg, not David Landsman! Bravo Mr. Landspurg. His obituary says that he was working for Motorola and supporting the Apollo missions, and passed away in 2014.
Apollo Comms Playlist: • Apollo Comms Part 1: O...
Links to doc:
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virtualagc.github.io/virtuala...
www.ibiblio.org/apollo/
www.ibiblio.org/apollo/Docume...
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00:00 Our Apollo receiver has been modified
05:20 Reverting the modification
07:41 Retuning the filter assembly
11:40 First receiver tests
13:38 How to extract downvoice with a ham radio
15:45 First voice trials, not working!
16:49 Tracking the fault in the spacecraft transmitter
20:35 Receiving downvoice!
Correction: 03:26 Frank Landspurg (not Landsman)
Correction: 05:09 Frank Landspurg (not Dave Landsman)

[@CuriousMarc]

Oh, no! I butchered the name of our hero engineer. He's Frank Landspurg (not Dave Landsman). After a long carreer at Motorola, he passed away in 2014. His obituary says that he was most proud of his supporting the Apollo missions. We are very proud of him too! If anyone knows any of his surviving relatives, let us know!

[@twotone3070]

Amusingly carrier works so well in this case and I appreciate two things here, one is that you speak in English for us and two, that career and carrier sound much the same when you say them. I love what you do on this channel and sit open mouthed through most of the episodes.

[@CuriousMarc]

Oops, French influenced spelling mistake. It’s been corrected…

[@twotone3070]

@@CuriousMarc Thank you for being so gracious.

[@StephanAhonen]

"CuriousMarc here, we managed to get ahold of five F1 engines, so we're going to see if we can get our restored Apollo spacecraft to actually land on the moon"

[@electronash]

I genuinely think they would, if they had the parts and funds. lol

[@paulcohen1555]

You just need three astronauts, and can go ahead!

[@todaysgrailtomorrowsbeater]

Hahahahaha😂

[@Runco990]

Do a collab with Elon, he just might be up for it!

[@tomsawyer8102]

Would probably do it faster, cheaper, and safer than Elon 😂

[@alexlefevre3555]

"If you could do a stir of your cryo-tanks." "No." You guys are my heroes.

[@garrettagainpogo4902]

I literally yelled out "no don't do that!"

[@twotone3070]

Sadly I don't understand.

[@alexlefevre3555]

@@twotone3070 The process of activating the damaged heating element in the cryogenic oxygen tank (colloquially "stirring" the tanks) is what triggered the cascade failure that crippled the service and command modules on Apollo 13.

[@UsagiElectric]

もしもし　かめよ　かめさんよ せかいのうちで　おまえほど あゆみの　のろい　ものはない どうして　そんなに　のろいのか Excellent video and was an absolute honor to sing a children's song from the moon!

[@benjaminhanke79]

07:47 "Use the following HP instruments" "I actually have one" These instructions were waiting almost 50 years for Marc to be discovered and executed.

[@paulcohen1555]

Big 👍 goes to the engineer who left the notes!

[@CuriousMarc]

He’s our hero. Unfortunately I butchered his name in the video, he's Frank Landspurg (not Dave Landman). He passed away in 2014 after a long carrier at Motorola. His obituary says that he was most proud of his work for the Apollo missions. I'll pin this info as a correction.

[@XouXin]

This is an amazing contribution to history and education. It’s a privilege to be able to watch you all use and explain the original hardware that aided in landing on humans on the Moon. It’s like watching someone make the pyramids before your eyes. One day this will be ancient history and you’re doing an amazing thing by keeping it alive.

[@Milten130]

It's super weird for me that we lost so much of technology history that we have to reverse engineer what "ancients" did. I wonder how much of current technology we'll lose in 70 years just because programs get cancelled or companies go bancrupt or stuff like GitHub is lost

[@alexander19681]

Very True.

[@colormaker5070]

I hope Mark Watney has added you to his contact list. This is a blast from the past my grandfather was one of the engineers that worked on comms at Colins radio in IA in the 60’s. We would often go outside and watch the moon. He told me we will be able to talk to people as they walked around on the moon. I was 5 years old and its a memory that I will have forever.

[@parkerlreed]

Every single one of these videos, I am amazed at how much technology we had even back then. You guys have done absolutely fantastic work documenting this and demonstrating it. Without this series, there would be a big void to be filled, that would probably never see the light of day. Thank you so much for this.

[@__Dude_]

It came a long way since Marconi. That was the peak of high frequency analog communication! Soon after, digitization started, and now we are working with SDRs.

[@Ronilac]

Each generation considers itself the smartest of all but when you look in the past carefully no fools gave us the basis to move up... We are standing on the shoulders of giants.

[@hoofie2002]

I don't have the same amount of kit and test gear but I DO have the same Icom 7300 ham radio the team are using so I have a strange glow of pride and kinship 😂

[@CuriousMarc]

Isn’t it a great little radio?

[@tomschmidt381]

As a baby boomer the Apollo missions were an exciting time. It is fantastic seeing this 1960's technology restored.

[@michiganmudduckradio7849]

the apollo 13 "will you stir your cryo tanks?" has me dead....

[@radarmusen]

Surprising that a paper sticker still can be readable after so many years, good thinking from an old nasa guy.

[@lmamakos]

I'm sure 100 years in the future, someone will say the same thing about the P-Touch label in comparison to the 3D holographic video labels used like we do QR codes today.

[@DrJaneLuciferian]

This is exactly what should be done with all the dusty space and computing equipment floating around museums. Almost everything could be revived with time and effort. I think this is one of the most important projects on KZbin.

[@ryansharp4020]

Now you lot just need an Apollo CM to put all that hardware into. It's awesome watching you all restore this equipment and teach all of us how it works in the process. Thank you!

[@masterman1502]

That's a bunch of test equipment, so I doubt it will fit there :D

[@TonyWeirPD]

I'm pretty sure they'll build their own at some point.

[@jasonmurawski5877]

@@TonyWeirPDget a bunch of makers together to build a replica capsule like they did when the hatch was recreated.

[@danielpeck6269]

This takes me back to studying Morse code as a child: ".... . .-.. .-.. ---" I actually ordered and checked out a training manual on vinyl record through the inter-library loan program and had to wait a week or two for it to arrive. I might have to pick that hobby back up again.

[@tekvax01]

Well, I know what I'm watching first thing tomorrow morning! Our Apollo communication engineering dream team repairing and demonstrating 50 years ago technology, that we love, in a way no other could explain!

[@rndullrobinson3076]

I was the a/g comm tech at the Guam tracking station. My job was setting up UHF links for them to talk confidentially. If you have any questions please ask

[@simonstergaard]

you have to install all this into a capsule at a museum...it will be epic !

[@staaaaalbeton]

You have to build a working Apollo now! After communications the power-generators you showed us at a collector a while ago!

[@ponyhorton4295]

I'm honored that you're using the Apollo Command Module Panels reference poster that I created for LunaReplicas!

[@CuriousMarc]

You did that? Well done!

[@Derrick6162]

Keeping Apollo alive, one success at a time. 👍👍

[@MarcoTedaldi]

Seeing that the fix was done in August I'm looking forward to many more episodes! 🎉

[@stepannovotny4291]

Nice job simulating your SDR in hardware!

[@Edisson.]

Absolutely amazing work, I came across this channel completely by accident and I'm glad I did. Your knowledge is amazing and the equipment is breathtaking, these videos far surpass (at least for me) any documentaries I have seen about Apollo. It started as a coincidence and today I regret that I cannot be at such a great project in person. Thanks for the opportunity to see this project at least with YT. I wish you a nice day and a pleasant Christmas 🙂 Tom

[@thewhitefalcon8539]

by accident, or by the algorithm?

[@Edisson.]

@@thewhitefalcon8539 Coincidentally, I was looking for some info on HP measuring technology and this channel came up in the video menu

[@PaulLoveless-Cincinnati]

This is BY FAR the most fascinating channel on KZbin.

[@cvkline]

Awesome, I thought you'd finished this grand tale, glad to see you're still working on this amazing equipment!

[@RocketCityTech]

These guys aren’t going to stop until they land on the moon 😂

[@thesmallterror]

Thank you for taping all this work! So exciting to watch!

[@RicoD5]

The Apollo saga continues 🚀Thank you for keeping the memory of this tech wizardry alive!

[@scowell]

Please bring that rig on tour... love to see it near me. Houston? Perfect! I'll drive hours from Austin. And... thanks for keeping this alive.

[@FrankGevaerts]

One very tiny detail that I found interesting is that the original equipment was marked in KC (well, MC in this case) while the modification used KHz. Assuming the 768 KHz label was original, that's a nice illustration of when exactly that notation changed!

[@sidharthcs2110]

I've never heard or seen anyone using that notation for frequency. What is that ?

[@brianl2607]

the modification could have been made any time after the notation change, right? so it wouldnt tell us much?

[@FrankGevaerts]

@@brianl2607 that's true...

[@FrankGevaerts]

@@sidharthcs2110 cycles, or in this case megacycles

[@herbertsusmann986]

Hey I still sometimes use "MC" instead of "MHz" when labeling something. Just can't forget the old days!

[@curtlundgren6867]

Thanks so much for continuing this amazing series!

[@user-sy6lc6hv7e]

Happy New Year, Marc! Great as always!

[@JimmytheCow2000]

Thank you so much for more of this! I really enjoy learning more about this stuff.

[@danieldare2640]

I just want to say thank you for all that you are doing and the amount that you are sharing. Truly remarkable thank you so much and Merry Christmas

[@malcolmgibson6288]

Thanks for the early Christmas present.

[@jlwilliams]

Yay! I've been enjoying the videos from other projects, but had been hoping for another Apollo coms installment. This is a great early Christmas present! Thanks, CuriousMarc and team!

[@markgreco1962]

Thank you for the wonderful Holiday gift

[@hymermobiler]

You guys just never fail to impress! Thank you so much for sharing!

[@Peter-House-Jr]

I am living vicariously through your channel. Keep up the good work!!!

[@VincentGroenewold]

So so so soooooooo awesome, without you all this would've been forgotten forever, thanks!

[@flyer617]

Awesome that you were able to gather all that equipment, and even more awesome that you were able to get it running.

[@EVPaddy]

Moon landing deniers should be forced to watch the whole series. Deeply impressed with the skills and knowledge

[@rogervanbommel1086]

Imma stay tuned to this frequency, hopefully another vid soon

[@euroclassicsnation]

So much fun to watch. Yet again it’s well above my understanding but so interesting

[@Techie_ASMR]

woah.. i just love this channel..

[@GeneralJackRipper]

Nice to see some progress.

[@brianwilson49]

i’m 2 minutes in and my mind is blown already! you guys are frickin incredible!!

[@emdxemdx]

I was about to turn blue waiting for the Quindar tones at the end!

[@tekvax01]

Marc you and your team continue to amaze! Thank you for your hard work, repairing and demo'ing this wonderful hardware! THIS is the best site on the KZbin platform!

[@TheFleetz]

The present that keeps on giving! 👍😀

[@mk1cortinatony395]

I didnt understand most of this but still think its brilliant that you guys go to this level to bring the Apollo hardware and software to life again. Fantastic!

[@srOmatic]

All the best from Oleron Island - France. You make us dreaming. And long live to HP instruments too :)

[@624Dudley]

This material is mind-boggling. Luckily, my mind really enjoys being boggled every so often 😁. Thanks Marc & company! 👍

[@darrinpearce9780]

You guys are my heroes. Fantastic job, love the cryo tank reference!!. 73's

[@68hoffman]

im so happy i found this channel ..i wuv what ya'all are doing there ...rebuilding americas history ..the nasa tech our granparents made "with maw bell "is what built our world we see today ..that may be a tall staement ..but look no furhter than your phone ..to know i am right ..merry x-mas marc and your faboulus team :) happy new year 2024 is gonna rock! :)

[@mrlithium69]

This is phenomenal retro re-creation!@

[@SpinStar1956]

I know that there is so much research and work that goes into all this reverse-engineering but I must say that we all appreciate these historic efforts. It is one thing to look at a bunch of legacy hardware, talk about it and lament it passing; but it is a whole-nuther thing to bring it all back to life for all to see. Very commendable effort, and you and your team should be very proud of these exceptional achievements. Also, telling the historical story is admirable as well. Thanks Again & 73...

[@canalcomentario]

Admiro tudo isso, saudaçoes do Brasil.

[@jimsn9624]

You guys are the best. I am an Apollo nut, so obviously I love this whole series. Thank you for all of your dedication, hours of reverse engineering and your top notch debugging skills. You fix extraordinarily complex electronics, but I retain probably 10% of it. However I have learned SO much from your channel. Thank you for sharing your knowledge. And happy new year!!!!

[@InvertedFlight]

I just got super excited when I heard the PTT beep

[@MarcelHuguenin]

What...? Did I hear Usagi Electric doing Eugene Cernans' famous "I was Walking on the Moon One Day" song? Oh no, he was probably doing a Japanese song 🤣 I love this series, you'll doing an amazing job. Great it's all taped for prosperity.

[@biniouhamoto1236]

Allo Houston, Bonjour de Belgique Marc ! et Merçi pour ces vidéos passionnantes🌎🚀🪐

[@lazerusmfh]

This was awesome

[@Roskellan]

Love this, I was 11 years old when I watched the first moon landing. At 16 I went to work at Goonhilly Satellite Earth Station where the first moon walk pictures were received off the Intelsat Satellite for broadcast in the UK and for some parts of Europe. As a Radio Amateur I have some of the test gear you are using including the Nixie Tube Counter and the Spectrum Analyzer - love HP kit from this era.

[@raymitchell9736]

Excellent work untangling the RF for the voice downlink... Who would have thought back in 1969 that you'd be working on restoring the equipment here in the SF Bay Area? It is a pleasure to watch every episode! I feel this work is historic in its own right and I'm glad to be here to witness it. P.S. I was a little boy at the time of the moon landings and didn't understand the significance, now that I do, I just love every technical detail of it. I had an opportunity to meet Buzz Aldrin on the USS Hornet for the 40th anniversary... And see the moon rock at Chabot Space science center.

[@Turambar3791]

Amaizing!

[@UpLateGeek]

Excellent work, as always. It's pretty mind-boggling to see what went into just radio communications to/from the moon. Nowadays you could probably get the downlink going using a digital TV tuner with an overinflated ego, AKA an SDR.

[@SimonBauer7]

yeah i assume thats what they will do the next time they go to the moon.

[@rickhole]

22 minutes well-spent! Great troubleshooting technique. When the notification popped up I dropped everything for another Apollo fix.

[@AdamosDad]

73's🎙KD9OAM🎧📻📡 🚧 As an electronics technician from the US Navy that was in the Pacific for Apollo 11's splash down. Our shipboard equipment was larger of course, but we used very similar equipment and procedures, to what I see you operate and restore in this video. Well done!

[@mikek5633]

Joyeux Noel Jean Marc !!!

[@mikesradiorepair]

To say your making progress would be a understatement. To say I spend half of my working life undoing modifications to radios would be a understatement. Seeing the modification documented in the equipment in my world a unexpected joy. You were blessed by the RF gods. Excellent work by you and the team. Curious, since I saw a modern amateur radio in the video are you a amateur radio operator? Mike KC3OSD

[@lwilton]

He got his license a few years back when they started working on this stuff. Don't know his call.

[@mikesradiorepair]

@@lwilton That's great. I'll have to keep a ear out for him on air. Maybe I'll catch him on air one of these days on HF.

[@clifforddicarlo9178]

Wow, this is neat!

[@SubTroppo]

My thirteen year-old self hardly gave the technical aspects any thought. It was just what was expected and accepted (shrugs shoulders). But now... ...and what is equally astonishing is that "they" are struggling to equal the achievement. ps Chapeau l'équipe!

[@jamesbrewer3020]

Thanks

[@unmanaged]

Marc would love to meet you one day... I am on another cost ... lol thanks for the great work and happy holidays

[@jeremiefaucher-goulet3365]

8/14/2023... Working on editing your video backlog I see ;-) Awesome video as always!

[@arcadeages3917]

Bravo! ❤

[@proehm]

I had a horrible flashback to retuning a 6 cavity input filter on a (tube) Motorola VHF mobile. I had an Eico RF signal generator for a source. (And an HT to verify its frequency.)

[@AltimaNEO]

22:02 Oh hey, David of Usagi Electric!

[@TheDefpom]

You probably should have tuned it with the cover on, as the cover could well have an effect on the tuning circuit.

[@ooosoo8727]

I get to see it within minutes of uploading!

[@beefchicken]

I’m glad you imported a Texan to play the role of Houston.

[@mahtin]

Fast forward fifty years and think of a future-Marc restoring a present day spacecrafts electronics (Dragon?). I’m not convinced it would be this interesting. We’d be watching s/w debug sessions.

[@LlamaAlarma]

That moment at 21:12 when it "locks in" is so cool

[@TheGmr140]

I see a lot of hp vintage test gear, be nice to see test specs, signal mds, selectivity, noise figure, min Snr needed, pll lock range, in any case, I'll gladly take your hp test gear after your Apollo videos wrap up. 😊😊😊

[@HotHammster]

Yeah. That HP test equipment is’80s vintage. Much closer to Apollo than today.

[@trewjohn2001]

One of the crazy moon conspiracy theories I hear is how the president was able to place a “phone call” to the astronauts. It was common place for Marine VHF and HF to patch into PSTN. Would be amazing if someone could find the patching equipment from the moon landings.

[@msylvain59]

12:18 Amazon has "plastic blade scrappers", same thing but a plastic blade is much less prone to damage paint.

[@williamsquires3070]

If I’m ever on a starship, and I can’t find Scotty, I’ll have to take CuriousMarc with me instead (and all the rest of the guys there with him.) 😀

[@raphaelchevalier2217]

fantastic work guys, are you planning on remaking a mockup apollo cabin to hold all pannels & boxes in place without risk of ripping cables or unplugging/replugging connectors the wrong way? Would love to help if ever needed.

[@contrapezist]

Traveling Wave Amplifier Tube

[@FUNKLABOR_DL1LEP]

Whoooo!!!❤

[@vincei4252]

7:49 Oh no! I could have shipped you my HP606 for authenticity!

[@yellowtomato]

Everytime I watch this video, it gets very expensive for me, I end up buying more HP test equipment soon after. 😂

[@CuriousMarc]

That's quite OK, one can never have too much classic HP test equipment! I think I have used every single HP RF instrument I have at least once for this restoration!

[@prillewitz]

I Do, I Do, I Do is from ABBA. I had expected a Christmas song like the astronauts did when they discovered a polair satellite!

[@68f100ranger]

Never been this early to a CuriousMarc video before!

[@stephano6793]

12:17 some gentle heat is your friend here.

[@bradnelson3595]

Come one. That's not rocket science. Oh...wait...yes it is! Well done, all. Amazing.

[@JulieanGalak]

Hey! A piece of test equipment I recognize and own! That looks just like my HP 3312A function generator! (Though it may be a slightly different version, can't quite tell.)

[@CuriousMarc]

Good eye, that’s what it is!