Test Equipment Anonymous (TEA) group therapy thread

[mansaxel]

The ham lifestyle is on the decline, for sure.

There is a large variety in hams in Sweden. Most, the ones we can call the mainstream, are quite technically competent (or would like to be seen as) and in general are likable people who have a partner, know of soap and hairdressers, and can sustain conversation on various subjects. But, there are two strains that diverge;

• One is a CB descendent, very often a caricature of an US trucker, complete with confederate flag, prepper lifestyle and a strong distrust in society. Would, in spite of above really like to be seen as "tactical". Despicable fools.
• Other is people with social disabilities, who have a basic craving to be accepted in a group, but lack the social skills and experience to actually understand how other people will react, and as the ham society in general is quite forgiving, these poor people have attached themselves like glue to the community. While taxing, I think they should be tolerated.

To offer some perspective, some of the smartest people I know have SM or SA callsigns. And are active in the community.

Our hamfests are quite on-topic, actually. The largest one is this Saturday in Eskilstuna. I'd like to go, but have promised to show up in the local "outdoor dance/party park" to go through equipment and plan for the summer projects in audio there. 

[Robert763]

In the UK hams fall mostly into those 3 groups too.

[factory]

Mnem, is this the kind of cheap Chineseum BMS 8S board that could be used in the Tek 422 scope & why only 7sections on the board? Would have been nicer to find something in the UK, but all those seem to be for larger solar/battery charging.


Original battery pack was 24V Ni-Cd D cells, I'm thinking of using LiFePo4 cells, I would need to modify the existing charger & low battery circuits on the scope.


David

[Cubdriver]

Some ebay items that might be of interest.

Someone please rescue this Racal counter from getting parted out, again too far for me (in UK), I did find one a year or two ago, expect lots of bad germanium transistors, I see they had to take the picture of it powered up in the dark too. 
https://www.ebay.co.uk/itm/115331251339


David

Damn - if that was here, I'd likely be all over it - cool old beast!

-Pat

[tggzzz]

Some ebay items that might be of interest.

I've heard of barn finds (which probably aren't), but never found in a field, quite poor condition bunch of HP 174x & 172x scopes, thankfully too far away for me (in UK). 
https://www.ebay.co.uk/itm/165418915392

Honest comment from the seller: "They all turned on last week but one didn't turn on this week. Have been stored under a tarpaulin". Not the only things, from the look of it.

You forget this gem, again from that seller.
https://www.ebay.co.uk/itm/165415965228

Same seller has a Tek Wreck 576, probably too far gone, but maybe a challenge for the brave. 
https://www.ebay.co.uk/itm/165418931698

Another honest commert: "I turned it on last week and after a while it smelt strange so i turned it off. Today when i turned it on to take photos after a while whilst i was doing other things i noticed it SMOKING, so turned it off straight away. Most of the dials and knobs work ok a few are sticky."

Personally I'm surprised it got that far; presumably he thought his concrete bunker wouldn't catch fire.

Someone please rescue this Racal counter from getting parted out, again too far for me (in UK), I did find one a year or two ago, expect lots of bad germanium transistors, I see they had to take the picture of it powered up in the dark too. 
https://www.ebay.co.uk/itm/115331251339

Are the displays worth parting out - to make a clock for example

[Cubdriver]

Some ebay items that might be of interest.


Someone please rescue this Racal counter from getting parted out, again too far for me (in UK), I did find one a year or two ago, expect lots of bad germanium transistors, I see they had to take the picture of it powered up in the dark too. 
https://www.ebay.co.uk/itm/115331251339

Are the displays worth parting out - to make a clock for example

Wash your mouth out with sulfuric acid!  Them's fightin' words in these parts!!   :  

-Pat

[Vince]

Vince, the Rochar DVM, is it possible the range switching problem was just dirty switch contacts,

I did give it some contact cleaner and exercised it, but not much luck...

I noticed it has relays for the auto ranging too. I also find the diagrams quite confusing.

You are doing much better than me though, for I had not even REALIZED there were relays in this freaking schematic ! 
Maybe I should send you this thing, you will fix it faster than me I am sure... oh wait but if you do it all then I won't have any of the fun and won't learn anything... ah well....

Anyway, no relays in the one I am fixing, as it's the 'D' suffix. It's Vdc only and no autoranging. There is just the main big range switch on the front panel, and that's it. My other meter is a 'B' suffix so it does do AC+DC and autoranging, so it actually does match the schematic perfectly.
I looked at this meter and yeah... I can see 3 big ass relays coils hiding deep inside the attenuator subassembly...

The attenuator section in the schematic I find extremely confusing, convoluted, complex, unclear, it's spaghetti to me. So having, on top of that, to guess what bits I need to mentally remove, "rewire"... to make it match my non-autorange and non Vac model... it's too much to ask frankly....

They provide waveforms measured at numbered transistors, but you found no layout or markings.

Yes, see below. That's the comparator board as an example... zero marking whatsoever. Just a bare bakelite board and a bunch of components thrown all over it and bob's your uncle 

Something I just noticed is some pages indicate Rochar were part of Schlumberger.

Yes and no. Rochar was self owned, created inthe mi '40s and after 20 years eventually Schlumberger bought and killed them, like tehy did with many other French TE manufacturers in those days. So they just slapped a "Schlumberger" branded cover page over the original / old Rochar service manual, and that's it...

Now biting the bullet, printed the schematic for the comparator board. If I study it long enough, as well as the board and theory of operation, maybe my brain will soak it eventually, and I will be able to look at the board and know what component does what where... Don't see much choice... it's not gonna fix itself all by magic 

[Cubdriver]

Honest comment from the seller: "They all turned on last week but one didn't turn on this week. Have been stored under a tarpaulin". Not the only things, from the look of it.

You forget this gem, again from that seller.
https://www.ebay.co.uk/itm/165415965228

As someone from the northeastern US, it still seems weird to me to see things stored outside at Apex in California, but they're basically in the desert and I've purchased several things from the outside yard that have been in pretty good nick once the caked on dust had been removed





but storing electronic instrumentation under a tarp in a farm field in the UK?!?!?       

WTF is the thought process there?       

-Pat

[tautech]

Just a bare bakelite board and a bunch of components thrown all over it and bob's your uncle 

FYI, that's not bakelite but FR2 or phenolic PCB.
https://db-electronic.com/en/pcb-manufacturing_s35.htm

[Vince]

Just a bare bakelite board and a bunch of components thrown all over it and bob's your uncle 

FYI, that's not bakelite but FR2 or phenolic PCB.
https://db-electronic.com/en/pcb-manufacturing_s35.htm

OK thanks will try and remember it....

1AM, I am going to bed with some sense of satisfaction : I made some progress on the bloody thing ! 

So as I said I am starting to "study" that "comparator" board (that's how the manual calls it, because well it contains the two required comparators that are needed to do the Voltage / Time conversion ).
I decided to start with the simplest of the problems it has, to wet my feet : the polarity Nixie doesn't light up at all anymore. Circuitry in the top right corner of the schematic posted earlier. Only a couple transistors a few diodes, 2 cathodes... it was a good candidate to get started on that board. Teh easiest to spot / identify on that board, was the 200V supply for the anode of the tube. Bingo... I measure zero volt ! Cool, that means all the circuitry is probably just fine and it's just a power rail missing ! 
The problem was NOT on the board... it was on the back plane / rear board where all the boards attach to with these 12 way card edge connectors.
The socket/female connector, soldered on that back plane, has a bad solder joint. It did NOT look bad at all... I only foudn it because well, I was tracing that rail with the continuity tester, so I quickly found that the joint was not making contact with the pad ! 
So I wicked that joint completely, and all others on that connector, to see what's what, and look at that ! That joint, and the next 3, did not stick at all to the pad ?! You can see 90% of the pad is still clean bare copper !  The other pads looked OK/ tinned.  Crappy PCB back then ? I put lot of flux when soldering back all these joints with fresh solder, hoping it will be good.

So that was it, cracked joint. It must have happened as I plugged and unplugged this board many times when swapping boards, and when I took it apart initially to take pictures.
Thing is, this board has not one but two 10 way connectors, so it takes quite a bit of force to nuplug it. 100% of that force is transfered to those solder joints becasue the connectors are not screwed down/ secured to the PCB. There is zero strain relief so to speak.

So now the polarity Nixie is back to life, look at that ! Even displays negative polarity, so I know the circuitry in there works just fine 

I do notice however, that the tube looks a bit "foggy", like a car headlight that's got moisture in it from damp weather... well this nixie look a bit like that. Also, at the back of it inside, I can see that scary, horrible... purple glow !! Oh no... it adds up ! This tube really sucked moisture, it's doomed ! 
It's still pretty bright though, but for how long...
I guess I better start searching for a replacement soon, hoping this particular tube model is still available. It reads on it " F9082 ", made in France apparently... can't believe that for one second.
A regular tube might be findable, but this particular one for the polarity and special symbols (odes also the " AC " sign, and also Omega for resistance )... maybe not so easy...

Good night people 

[tautech]

Oh yeah, someone was being real mean with the solder when they made this and as there's so little thermal cycling was sure to crack the solder joints.

[tggzzz]

Some ebay items that might be of interest.


Someone please rescue this Racal counter from getting parted out, again too far for me (in UK), I did find one a year or two ago, expect lots of bad germanium transistors, I see they had to take the picture of it powered up in the dark too. 
https://www.ebay.co.uk/itm/115331251339

Are the displays worth parting out - to make a clock for example

Wash your mouth out with sulfuric acid!  Them's fightin' words in these parts!!   :  

What other use could it have? Turn it on end and have a light bulb sticking out of it?
https://www.ebay.co.uk/itm/153997204152
That perpetrator didn;t have the wit to turn it upside down so it looks like a smiley.

[cyclin_al]

Anyone looking to add a "screenshot" option to their Tek 400 Series? https://www.ebay.de/itm/115332266476

McBryce.

And surprisingly you can still get the B/W film for the camera. No, not interested.

I wonder if there is a way to mount a CCD sensor inside that?  You could then get digital imaging and keep that nice retro hardware.

Unfortunately, I don't think so - at least not without changing the lens.  The image plane is the film face, so unless you change the lens focal length you'd need a sensor the same size as the film is, and given the price of medium-format digital cameras, I don't want to even think about how much something like that would cost. 

I agree that it would be pretty cool to somehow rig a digital scope cam in the original camera body, but just can't easily think of a way of practically doing so.

-Pat

Ooof!  I did not realize it was medium-format.  In that case, the cost would be scary 
My assumption was that it would be 35mm, as this size was the most common before everything went digital.  In that case there would likely have been many choices for a sensor or sensor assembly for 35mm...

[Cubdriver]

Anyone looking to add a "screenshot" option to their Tek 400 Series? https://www.ebay.de/itm/115332266476

McBryce.

And surprisingly you can still get the B/W film for the camera. No, not interested.

I wonder if there is a way to mount a CCD sensor inside that?  You could then get digital imaging and keep that nice retro hardware.

Unfortunately, I don't think so - at least not without changing the lens.  The image plane is the film face, so unless you change the lens focal length you'd need a sensor the same size as the film is, and given the price of medium-format digital cameras, I don't want to even think about how much something like that would cost. 

I agree that it would be pretty cool to somehow rig a digital scope cam in the original camera body, but just can't easily think of a way of practically doing so.

-Pat

Ooof!  I did not realize it was medium-format.  In that case, the cost would be scary 
My assumption was that it would be 35mm, as this size was the most common before everything went digital.  In that case there would likely have been many choices for a sensor or sensor assembly for 35mm...

No, to the best of my knowledge, all the scope cameras (at least all that I’ve seen) used Polaroid instant film, so alas no easy way to make them digital.

-Pat

[Cerebus]

Anyone looking to add a "screenshot" option to their Tek 400 Series? https://www.ebay.de/itm/115332266476

McBryce.

And surprisingly you can still get the B/W film for the camera. No, not interested.

I wonder if there is a way to mount a CCD sensor inside that?  You could then get digital imaging and keep that nice retro hardware.

Unfortunately, I don't think so - at least not without changing the lens.  The image plane is the film face, so unless you change the lens focal length you'd need a sensor the same size as the film is, and given the price of medium-format digital cameras, I don't want to even think about how much something like that would cost. 

I agree that it would be pretty cool to somehow rig a digital scope cam in the original camera body, but just can't easily think of a way of practically doing so.

-Pat

Ooof!  I did not realize it was medium-format.  In that case, the cost would be scary 
My assumption was that it would be 35mm, as this size was the most common before everything went digital.  In that case there would likely have been many choices for a sensor or sensor assembly for 35mm...

That camera takes Polaroid Type 40 roll film, which has a frame size of  3¼" × 4¼" (8.2cm x 10.8cm). Quite a bit larger than the 6x6 cm 'medium format' frame size.

[Zucca]

How much HP 34401A 2W ohms digits usually differ from its outputting measurement voltage?

Obscure question, if you are doing a 2W R measurement, why you want to know the voltage? What it counts is the V/I ratio.

[Zucca]

WNR

The WNR defines the ratio in dB between the wanted power [W] over the needed power [N] for a device that can/should be purchased or it is already purchased.




TEA members present always high levels of WNR, generally above 20dB.
Generally speaking the WNR and MWC (money wasted coefficient] are in direct proportion.



In my last purchase


I measured a 62.3 dB WNR peak.

[AVGresponding]

How much HP 34401A 2W ohms digits usually differ from its outputting measurement voltage?

Now HP says 0,15013 kOhms and Fluke 8505A says 0,14909 V.
Leads are around 0,0001.

BTW,
Temperature dependency of one Volt Ref. AD584-M.
As in room temperature oven with a fish.

0,15 mV / 9,5 C sharp

I'll check when I get home from work. If I remember...

[mansaxel]

WNR

The WNR defines the ratio in dB between the wanted power [W] over the needed power [N] for a device that can/should be purchased or it is already purchased.




TEA members present always high levels of WNR, generally above 20dB.
Generally speaking the WNR and MWC (money wasted coefficient] are in direct proportion.

There's a referencing problem in your formula, and dB being unspecified is relative!. I'm somewhat curious as to what your references are.  Being somewhat entrenched in RF and opticks I tend to use dBm and regard 0dBm as a nice generally useful level, where there would, for Needed values exist a state of "This would improve things I do daily". I wanted my DM42 like 20dBm, which is a lot. I needed it about -5dBm which is strong, but not necessary at all.

10Log * ( 20/-5 ) = -4dB

N values being negative mess your formula up.

Proposed W values, related to 0dBm:

30	I need a complete set, desperately
20	Wantwantwant!
10	This is an interesting instrument...
0	Would look good on the bench
-10	If it had Nixies, I'd buy it
-20	I could do with a parts unit
-30	I have like 5 already, in better condition

This needs standards and committee work. Your move.

[Robert763]

How much HP 34401A 2W ohms digits usually differ from its outputting measurement voltage?

Now HP says 0,15013 kOhms and Fluke 8505A says 0,14909 V.
Leads are around 0,0001.

<SNIP>

That is because the nominal 1 mA test current is a little bit low. It does not matter exacty what the current is becuase the measurement is ratiometric.

[McBryce]

My guess: 2 actual HAMs, the rest of the occupied tables operated by various different entities flogging the same exact household and makeup wares from the nearest Freight-reclamation liquidator.

And one crusty old bastard selling crusty-ass and broken hand-tools for more than they cost new; may or may not be the same person as one of the two actual HAMs.

mnem
 

Don't forget the crusty ham guy with the soggy cardboard box full of rusted PL-259 connectors and uselessly short pieces of old coax.

McBryce.

[vk6zgo]

Anyone looking to add a "screenshot" option to their Tek 400 Series? https://www.ebay.de/itm/115332266476

McBryce.

And surprisingly you can still get the B/W film for the camera. No, not interested.

I wonder if there is a way to mount a CCD sensor inside that?  You could then get digital imaging and keep that nice retro hardware.

Unfortunately, I don't think so - at least not without changing the lens.  The image plane is the film face, so unless you change the lens focal length you'd need a sensor the same size as the film is, and given the price of medium-format digital cameras, I don't want to even think about how much something like that would cost. 

I agree that it would be pretty cool to somehow rig a digital scope cam in the original camera body, but just can't easily think of a way of practically doing so.

-Pat

Ooof!  I did not realize it was medium-format.  In that case, the cost would be scary 
My assumption was that it would be 35mm, as this size was the most common before everything went digital.  In that case there would likely have been many choices for a sensor or sensor assembly for 35mm...

It was a Polaroid based thing---their cameras always struck me as looking like they were designed by someone who had never seen any other cameras, & was going by a very vague description!

[Peter_O]

...
I've heard of barn finds (which probably aren't), ...

Found some hay in my 2nd hand lambda 30 amps switching psu.
You can often see hay in the vents of strong PSUs.
They seem to have second lifes in the barns loading akkus of seasonal farm machines.

[tggzzz]

I've heard of barn finds (which probably aren't), but never found in a field, quite poor condition bunch of HP 174x & 172x scopes, thankfully too far away for me (in UK). 

At least one auction house stores equipment in a farm barn, the green building on the left. I've seen hessian sacks over the equipment to catch the condensation from the air.

[Saskia]

FedEx just brought a Mouser box with the Kria SOM which was on backorder.

Postal service dropped permanent "disabled" id for Hubby.

They also dropped off a speeding ticket. Bloody hell ....