Test Equipment Anonymous (TEA) group therapy thread

[med6753]

Was that the one you were trying to sell me at Harwell? 

Quite possibly, but not sure; I've sold several. You would have got a bargain, tee hee.

It is rare to find a visibly working one. The front page of the military service manual gives clues as to why many of the fleabay examples are in suboptimal condition...

Interesting. My youngest brother was in the Army in the late 1980's, early 1990's, and he was a tech on the Patriot Missile system at Ft Hood in Texas. The same time as Desert Storm. He told me things about the Patriot that at the time no civilian had the right to know. For example, the system was never designed to take down missiles. It was just an anti-aircraft system. If you recall Iraq was threatening, and finally did, launch scud missiles. It was launching them at Israel that had everyone shitting their pants. Massive effort to modify the Patriot software to intercept scuds...which it did....sort of. SOP to try to insure a "hit" was launch two at a time, rather than one. And to complicate matters scuds broke up into multiple pieces when coming back down.

My brother wasn't posted over in the sandbox, he was attached to the training group that showed others how to use the Patriot, including Israelis. He waved at those groups that went over seas and said "good fucking luck"   

[bd139]

That's why they came up with the Patriot F series. More than that I cannot say until 2047

[med6753]

That's why they came up with the Patriot F series. More than that I cannot say until 2047

Yep. 

Why is that black helicopter hovering over my place? 

[BU508A]

That's why they came up with the Patriot F series. More than that I cannot say until 2047

Yep. 

Why is that black helicopter hovering over my place? 

They need an emergency blue-painting.

[25 CPS]

One multimeter isn't enough.

I was thinking of a visit to a friend's place about 10 years ago.

The friend was into vintage stereo equipment and I picked up for cheap (<$20) a fairly rare FM tuner at a garage sale so I called him up and went over with it to plug it in and try it out for the first time.  Dead.  So my thought was to grab a meter and start checking voltages and he said no, he's using his meter to keep watch on a car battery that was being trickle charged inside his apartment.  It turned out he only had one multimeter and he didn't want to take it off the battery that was being charged up.

I've always had more than one multimeter even if they were just mediocre Canadian Tire Mastercraft DMMs when I was starting out because you might need one in more than one location or need to observe multiple parameters or multiple test points at the same time or have more than one project on the go, so it totally floored me that this guy who was into electronics had only one.  This was even more surprising since he used to trickle charge car batteries frequently like this which means the multimeter was occupied for hours or days at a time which automatically meant that he was totally stuck unable to do any other electronics while this battery charging nonsense was going on.

I swore I'd never get stuck in that predicament after seeing this.  I have more than one multimeter.  Way more than one!  That was the thin edge of the wedge, the start...  How many do you guys have?

[AVGresponding]

Picked up a package from the Post Office this morning on my way to work.

Jiffy bag with a heavy rectangular object in it.



Hmmm, what could this possibly be, the only things I'm waiting for are small or big or... OMG FFS NO, SURELY NOT, THE FLUKE 289!?!




In what twisted parallel universe of dumbshittery does someone think it's ok to send a £600 (when new) DMM through the post in a fecking JIFFY BAG?
I swear I'm losing the will to live...

Oh but wait, there's extra packing material inside! Time for a guessing game, free internet cookie for the first person to guess what packing material they used.

[Ero-Shan]

Next up: The Schroff. It appeared more "professional" to me.

At first, everything seemed to be alright. Voltage could be set, meters displayed reasonable numbers.
Let us open it anyway, if only to satisfy my curiosity. A few surprises were waiting for me! Alas, I forgot to take more pictures, but I don't want to open it again!

So here is a view from above. What amazed me were the flimsy cables. Yes, it is just a 1 amp PSU, but it is a PSU nonetheless! What are these? AWG26? They used the same for the mains. Of course, the current is almost negligible, but the insulation is also looking rather frail (arrow points to mains).



The PCB is a "Europakarte" with holes for the old 31-pin connector on one side. And a 1000 µF filter cap for 1 amp load? I think I remember a rule-of-thumb from more than 40 years ago: Use 3 µF/mA.
The regulation part seems to be hidden under that glued-on plastic cover. My curiosity had dropped significantly, so I didn't bother to get it off.



There are more oddities. The sense inputs (-F and +F) are internally shorted to the outputs. The amp meter sports an antenna and appears to have been replaced.



That unit was clearly not in its original state! On we go. 2 2N3055 pass transistors. For 1 A. Comfortably inside the SOA of a single 2N3055. (The Conrad PSU used a single 2N3055 for 30 V/2 A). No need for current sharing. They sit on the same heat sink, so power is limited by that. The only positive effect that I see is the halved thermal resistance from case to heat sink.



Then I took a closer look at the output: Holy shit! (It is not quite as bad as it looks - the input is scaled as 10:1, but fed directly; displayed voltage is 10 times actual voltage).
There's quite a bit of ripple. Though not of the expected 100 Hz kind, but 100 kHz!



There's no chance to find schematics, so I looked at the one easily accessible capacitor - across the output terminals. a 22 µF/35 V electrolytic. It was numb. Replaced it with a 22 µF/40 V one, and the output was quiet!
(Yes, the filter cap was also easy to get at. And it had exactly the 1000 µF it claimed to have.)

Then I got eager and replaced the shorts between output and sense inputs with resistors. I took 820 Ω/4 W (Accidentally shorting +F to - shouldn't toast them). The thing went unstable. Without further ado, the shorts went back. It now works quite nicely, but somehow I'd rather use other PSUs.

Final shot after removing stickers (except the safety check one) and a modest amount of cleaning:

[bd139]

Picked up a package from the Post Office this morning on my way to work.

Jiffy bag with a heavy rectangular object in it.



Hmmm, what could this possibly be, the only things I'm waiting for are small or big or... OMG FFS NO, SURELY NOT, THE FLUKE 289!?!




In what twisted parallel universe of dumbshittery does someone think it's ok to send a £600 (when new) DMM through the post in a fecking JIFFY BAG?
I swear I'm losing the will to live...

Oh but wait, there's extra packing material inside! Time for a guessing game, free internet cookie for the first person to guess what packing material they used.

Newspaper?

Makes me laugh but I ordered a bottle of ferric chloride off ebay a couple of years back and it arrived in a jiffy bag 

[AVGresponding]

Newspaper?

Makes me laugh but I ordered a bottle of ferric chloride off ebay a couple of years back and it arrived in a jiffy bag 

Nope.

[bd139]

Underpants? 

Thanks to a member of another forum I think I may have my hands on another unfinished but complete Radcom spectrum analyser 

[Brumby]

Underpants? 

Thanks to a member of another forum I think I may have my hands on another unfinished but complete Radcom spectrum analyser 

 

Why am I seeing: Spadcom rectum analyser...?

[Brumby]

Seeing that bubble wrap is too ordinary, I'll go for paper towel...

[bd139]

Why am I seeing: Spadcom rectum analyser...?

Oooeeerrr 

[Brumby]

.... maybe that should have been toilet paper

[PA0PBZ]

@Tony, look what I found for you: https://www.marktplaats.nl/a/doe-het-zelf-en-verbouw/meetapparatuur/m1595600742-hung-chang-8100a-multifunction-counter.html

[tggzzz]

Oh but wait, there's extra packing material inside! Time for a guessing game, free internet cookie for the first person to guess what packing material they used.[/color][/size][/b]

Without looking at other responses, newspaper or that stuff patented by Tektronix: foam peanuts.

I'll ignore the possibility of bubble wrap because that is vaguely sensible, unless de-zitted.

[tonyalbus]

@Tony, look what I found for you: https://www.marktplaats.nl/a/doe-het-zelf-en-verbouw/meetapparatuur/m1595600742-hung-chang-8100a-multifunction-counter.html

Thanks!
i indeed thought about it for a second...its super cheap, but i did have that one branded with an other name, they are quite good, it has an xtal oven ans is very stable... i was supprized

[AVGresponding]

Underpants? 

Thanks to a member of another forum I think I may have my hands on another unfinished but complete Radcom spectrum analyser 

LOL nope   

Seeing that bubble wrap is too ordinary, I'll go for paper towel...

Nope

.... maybe that should have been toilet paper

...and we have a winner!





The next guessing game is, what condition did the meter arrive in?

[mnementh]

Have fun! 

Ken Shirriff has another interesting blog. Larry Bower, the designer of the ca 1974 -hp- "Nanoprocessor" 1820-1691, kept the original photolithography masks and has released them. If you have a way to manipulate Photoshop files, you can download it and explore!

http://www.righto.com/2020/09/inside-hp-nanoprocessor-high-speed.html?m=1

That's neat... but I think Ken's deep-dive into the thing is more than enough full-frontal nerdity for one cup of coffee... 

mnem

[Specmaster]

That's why they came up with the Patriot F series. More than that I cannot say until 2047

Yep. 

Why is that black helicopter hovering over my place? 

Intimidation tactics to make sure you don't repeat anything bd may have said. If they start dropping ropes down, run like Feck for your life   

[AVGresponding]

That's why they came up with the Patriot F series. More than that I cannot say until 2047

Yep. 

Why is that black helicopter hovering over my place? 

Intimidation tactics to make sure you don't repeat anything bd may have said. If they start dropping ropes down, run like Feck for your life   

Given how military procurement normally works, the ropes either won't be long enough to reach the ground, or won't have the requisite load capacity.

[bd139]

They'll be really really expensive ropes though! 

[Specmaster]

If they use the same system as we do for PPE, they will also be past their use by date and be dangerous to use 

[med6753]

They'll be really really expensive ropes though! 

Does the UK also have the Patriot Missile Defense? If you do I wasn't aware of it.

[mnementh]

As someone who likes to wear T-Shirts I wanted to have one with a TEA logo on it.
But I wasn't able to find such a logo, perhaps I've overlooked it somehow.

If we don't have a TEA logo, is there somebody here with us with some
graphical and artist talents (and is willing to do) who could create such a logo?

My abilites in this respect are fairly mediocre.

Any ideas, how such a TEA logo should look alike?

I've contemplated, off and on, about having T-shirts made. Of course, that requires a logo to start with. I created a TEA YouTube channel, just in case, but since we don't have a logo, I just put a good ol' CRO instead.

The ideas for either a logo or a t-shirt design so far are quite fun to see. Keep 'em coming. And the two are not mutually exclusive. For example, the logo could go on the front in the "pocket" area and a full design on the back. I'd definitely want to have them silk-screened. No thermal transfer rubbish! So, that'd probably require a batch run.

A logo idea that's been bouncing around in my head for a while is a tea cup with a DMM in it. It can be kept clean and simple (bd139 is spot on there), which is important for many reasons including clarity at various sizes and robustness across different media including embroidery where too much detail fails and too many colors gets really expensive. Interesting to see that Mnem's TEA dragon illustration is mighty similar.

I also like bd's retro concept with that vintage Tek logo mod.

So, keep the ideas flowing. Maybe this weekend I'll try to create the logo that's in my head and see if it looks better, as good as, or terribly worse than I imagine.

I've often thought that some version of the Infinite Improbability Engine meme would be spectacularly appropriate; especially given our membership's almost universal appreciation of Adams' sense of humor.

Here's a template with a blank plaque for anybody to fill in using tour favorite photo editor (as long as it supports transparent backgrounds like Paint3D, etc do). Don't forget to keep it .png or the transparency will vaporize.

mnem