curiousmarc

And we have TV from the Moon!

A small step for CuriousMarc & Team, but a giant leap for the Apollo communications restoration project. We just transmitted a black and white TV picture using the original Apollo microwave equipment. 

Here is the setup. Our repaired NASA PM transmitter, PM receiver and FM receiver on the left, earth side. We'll only need the FM receiver for this TV transmission experiment. In the middle, an old B&W TV monitor. On the far right, our Apollo transponder, with a period-correct...

Nevada Haul

https://youtu.be/z0mXPbxbMiI

I'm just back from a trip to Nevada where I attended the Nevada swap meet and met with awesome Patreon John L., who once again saved and donated rare vintage equipment to the channel. Here is a preview of all I got!

Marc

Hewlett-a-Sketch with a HP 7035B X-Y recorder

Disabled viewer Kevin Counihan had donated a HP 7035B plotter to the channel a while ago. I finally got to it, because I needed it to plot curves for an audio filter I made for the Apollo setup. 

It did not work at all at first. A shorted cap replacement later, and it worked for a while before stuff started to go south again. This device uses photo-chopper servo amplifiers. It's an early low DC-drift, low bandwidth precision op-amp made with transistors, neon bulbs and photore...

Power RF components donation for Apollo testing

We just received a these hefty RF components, donated by R&D Microwaves. These are two 100 W loads, a 200W directional coupler, and a 30 dB 100W attenuator. R&D Microwaves is a company in New Jersey that makes specialty RF passive components. Check them out at www.rdmicrowaves.com. Michael Antkowiak runs the business, and his father designs the devices. Michael simply reached out and asked if there could be anything of interest in their catalog that they could contribute. 

...

Tek 222 Oscilloscope Video Early Access

I got a bogus copyright claim on my next video about the fantastic Tektronix 222 mini oscilloscope. Always annoying. But let's turn this into an opportunity and give the Patreons early access while this is resolving!

https://youtu.be/HlYOgXKnHvI

Enjoy!

Marc

Nice video about the IBM 360

Not my video, but we have collaborated with the CHA channel in the past. This one has some footage of “my” IBM 360/50 that I had not seen before, as well as the footage of the NASA RTCC in Houston from the Apollo times.

Marc

Will be on Keysight’s “Live from the lab” Thu. May 19, 9 am Pacific

Well that would be later today in my time zone as it’s past midnight. Sorry for the late notice, I just found out myself about the live chat part. They’ll show a video they shot in my lab and I’m supposed to be on the chat. Register here (free of course):

https://live.keysight.com/series/lobby246/lobby_button

Marc

Clutch job on the big IBM tape drives

The IBM 729 vacuum column tape drives at the Computer History Museum need our help again. I am working on a tape that won't load because of a mechanical problem, and Ken is working on one that won't load because of an electrical problem. These are major repairs, they have been going on for over a month.

We think my problem comes from a bad magnetic clutch on the right reel. Here is the partially disassembled right reel shaft, at the back of the machine. It's temporarily suspended with z...

The Cutest Tektronix O'scope

Meet my new old Tektronix 222. It's a classic early digital scope from 1988. At 2 channels, 10 MHz, 8-bit sampling at a rather pokey rate, it's not a screamer even for the time (my monster Tek 7854 samples to 10 GHz!). But it's so small and portable and easy to use.  The CRT display clocks in at an adorable 2" wide, extremely sharp and constrasty. And, imagine that, it's a battery powered CRT scope! But foremost, it's just so puppy-cute you'll want to adopt it.

Even in this age of ...

Stanford Dish Visit

Well, wouldn't you know it, Steve M., the current engineer for the nearby SRI space antenna, better known as the Stanford Dish, is watching the channel. This thing is a mere 10 minutes from where I live, and I had always wondered about it. So imagine my surprise when Steve recently contacted me, wondering about the role of the Dish in the Apollo program. He could find some traces of Apollo related equipment in the warehouse and observation notes in the log books, but nobody at SRI remembered ...

Teletype Model 31

This footage is courtesy of Patron John L. He recently got a Teletype Model 31 going. He told me it is a small portable teletype originally meant for airplane use. It prints on a narrow 1/4 inch ribbon. Congrats John, it looks spectacular!

Opening the Apollo Pre-Modulation Processor

We just opened the PMP, or premodulation processor box. It's the box that comes after (or before, depending how you look at it) the transponder. It is described by Collins as the heart of the system. It is in charge of modulating and demodulating all the sub-carriers. It's of pretty spectacular construction.

In and out of this thing comes the voice. The digital data downstream goes directly int...

NASA PM Tx back on Apollo frequency, link double-locked

There are a lot of good looking vintage green lights in the lab tonight. We have just successfully returned the NASA PM transmitter to its original Apollo frequency. Our Apollo transponder now locks onto our NASA test PM transmitter uplink, and our PM receiver phase locks on the spacecraft transponder downlink. Solid double locked PM S-Band link, as in the good old days.

I previously posted how we retuned the receiver after we got our custom ordered crystals from Laptech. For the receiv...

Apollo S-Band SDR Reboot

Many of you have asked how one would redo the Apollo link with modern electronics. And I believe one of the nicest way to do it would be using SDR (Software Defined Radio) technology. At least for the ground station where your electronics are not sensitive to radiation, and you can use the best and latest.

The SDR concept is straightforward: radio receiving or transmitting is nothing else than mathematical processing of very fast signals. Band filtering, frequency shifting, modulation a...

The Apollo PM receiver is back on its original frequency!

We finally received the crystals from Laptech in Canada. Frequency is right on the money (new one at left, the old one at the "wrong" frequency at right). They were spec'ed at +/- 10 ppm and we got -1.8 ppm!

The realignment of the VCO is an "engine out" procedure, with the VCO on the bench in a test harness we had to build.

2022-01-31 20:02:13 +0000 UTC View Post

Another vintage components donation

A viewer that wishes to remain anonymous rescued a batch of old components from the dumpster of his company. And they are quite interesting. They are mostly from the early 60's. Early Germanium semiconductors for the most part, mostly professional / higher end. I don't have much Germanium stuff in my collection, so this turns out to be a great addition. They'll come in handy to repair the early transistorized HP stuff from the1960's.

See this really early Germanium transistor, an OC47. ...

Monster E&L Breadboad System

Thanks to your support, I just got a big bad vintage solderless breadboard system off eBay. Actually, two of them.

We use breadboards quite a bit in the lab, and when there are several of us and several projects running at the same time, I need to have enough around for everyone. 

I have a pile of simple bare breadboards of course, but the most popular item is the E&L Instruments Digi Designer DD-1, pictured below. 

It comes from late Ron Crane's home lab. Ron ...

HP 9825 Crowbar

I wanted to keep the crowbar design for the last episode and grand-finale of our HP 9825 repair series, but this is dragging on as we have been distracted by Apollo stuff and the re-emergence of Covid, and have not completely repaired the tape board yet (although it's mostly up now thanks to Eric). 

However, one of you requested the design so he could go ahead and power his units without fear, so I uploaded my crowbar design on my website. You can find it here:

2022-01-12 05:28:40 +0000 UTC View Post

The IBM IO Tester thinks it is a chronomter

https://youtu.be/sv0nwF3uzUY

I just hooked up the restored IBM IO Tester blinkenlight panel to an Arduino to make it blink a bit...

Marc

Large IBM installation in the 1970s

A tip from a viewer, this video has really neat footage of an IBM datacenter, an IBM 370 I presume. Gorgeous and iconic IBM terminals, the super duper 20,000 line per minute laser printer. Not sure if the tape drives are IBM, they look like compatibles to me. Enjoy, and bonus points to those that can identify the exact pieces of hardware.

Marc

HP 8568 RF Analyzer: Restoration within a restoration

In previous posts, we explained that will need to retune our Apollo PM test receiver to the original Apollo CSM frequency, because its frequency had been changed to support another project, one of our best guesses being the Viking launch in 1974. 

Fortunately we found the manual a month ago, and it describes the involved procedure in detail. For that, we'll need a RF analyzer. I was going to use my HP 8568, but when I turned it on, it had this interesting modern art "deconstructed"...

Quick IBM IO Tester Restoration

You probably remember seeing us unbox this big gray box recently. It is a donation from viewer Brad Proffit (thanks Brad!). 

He did not know what it was, but Carl quickly identified it as an IBM IO Tester. It was a piece of debugging equipment from the 1960's, for the IBM 360 peripherals. You could hook it up to a supported printer, card reader, or disk controller, and it would give the cu...

My TI Silent 703 terminal is overclocked!

Next in our unboxing was the TI Silent 703 from eBay. This one started strong, printing its waterfall test with no problems, in eerie silence:

Still in local mode, I discovered it had two character width settings. One yielding a standard 80 characters per line, and the compressed one yielding 132 characters per line, like an IBM  printer:

2021-11-06 21:11:48 +0000 UTC View Post

We made two good HP 4957A with two bad ones!

You saw us unbox my HP 4957A in a previous video, and as expected, it did not even power up. This was a cheap non-working machine I got for parts. This was to help getting my other  "good" HP 4957A working. 

The "good" one was a clean machine, complete with all the application disks, documentation, and cables. And it worked almost perfectly. 

Except that the feature I really bought it for did not work: the high resolution, 80 character per line VT100 terminal emulat...

(Spoiler Alert) Good job Patreons on guessing the PS/2 fault

Here are the results of the poll:

And you guys did pretty good, much better than the average commenter that thought it was a cap. Well the average commenter *always* tells me it's a cap, no matter how much I show and explain what the fault actually is in the video.

As you can see, the most popular Patreon guess was a broken trace in the PCB. It's very close but no cigar. The second guess ...

Original manual for our PM receiver found!

Over the week-end, Mike, Marcel and I flew to a private collector that might have other items to help us with our Apollo comms restoration. The collector, who is super nice, is also very private and wishes to remain anonymous. While Mike was foraging in his many documentation shelves, he found this.

It said: support manual for the Apollo Block II Special Test Equipment PM RECEIVER. And it's fro...

Place your bets on the PS/2 “planar” (motherboard) fault

Las Vegas time! Put in your bet! 

In Part 4 of our IBM PS/2 repair adventure, Eric changed the IO chip and finally got the “planar” to behave. But it worked only after he prodded it with his magic finger or put cold spray on the IO chip. Then it seemed to work fine for a while, but even then we got it to fail a couple more times. There were many opinions about this intermittent fault i...

Apollo PM Test Receiver First Light

I am falling further and further behind in my videos, but our current latest advance was to power up the PM test receiver. Previously we had done receive tests using an HP mixer to bring the microwave signal back down to an IF of 20 MHz, then I used my HF ham radio as an IF section and got the FM baseband out of it. Good enough to confirm we could hear a tone from the PM and FM downlinks of the transponder, but the demodulation is not correct (much too narrow for the Apollo FM and no real PM)...

Apollo Uplink Box Progress

https://youtu.be/nALBEotYQzs 

You might remember our mystery uplink command box that we got from Marcel, completely undocumented, full of weird modules and with some parts missing. Last time I posted about it, I had barely managed to manually trigger the paper tape reader. In the meantime, Ken has been using hi...

To the Moon and Back with the Apollo Transponder

Progress continues with our power up of the Apollo transponder. We achieved frequency locked turnaround transmission: from Earth to the Moon, then back. With Earth being simulated by the two antennas at the far end of the table attached to my growing pile of HP equipment, and Moon being the two antennas in the near corner attached to our Apollo S-band transponder. This setup is getting monstrously complicated, and we have hardly scratched the surface of the full S-Band system setup.

You...