Test Equipment Anonymous (TEA) group therapy thread

[ch_scr]

It's Friday evening, time for some Fun with TE!
Todays star of the show: a low noise preamplifier

Also, sorry for the big pictures Vince.

Good Lord.... have I sinned to deserve such a punishment ?!  18MP 3.5MB per pic 

I am confused. Image #1 of ch_scr here show to be 2400x1600px with abt. 800kB. med's images are way larger...

They were at the time of his post... I have atoned my sins in the mean time...
Edit:
Also, to make this post not a total waste of space: I did succumb and get that philips ips from the local kleinanzeigen,
to my defense it was within walking distance and only 10€. Now I am blessed with this mess:

It has a nice thin bezel, but was mostly hold together plastic clips. That means getting it apart was... interesting.
Now on the pcb, we are greeted by lots of physically too tiny capacitors that are tired by now (monitor is 8 years old).
I'll see what I can do about that tomorrow.

[BU508A]

Echoes from a distant past

Part four - The Rohde & Schwarz Vacuum Tube Meter URI BN 1050

Edit:
Part one - Siemens Rel. send. 22b
Part two - The Two Transformers
Part three - The Rohde & Schwarz NGU laboratory power supply unit for vacuum tubes
Part four - The Rohde & Schwarz Vacuum Tube Meter URI BN 1050
Part five - The Rohde & Schwarz UVN BN 12001 NF Millivoltmeter
Part six - The Nordmende digital multimeter DIVO 3355 (with Nixie tubes!)

Hello,

today I'd like to introduce the Rohde & Schwarz URI 1050BN vacuum tube meter which capable of measuring DC volts and currents, AC volts and currents and Ohms. The meter has been produced in the 50's and 60's of the 20th century. It has an impressive wide measurement range. It can measure:
- DC current starting with 2nA up to 1A
- DC voltage starting with 20mV up to 300V (30kV with the 30kV probe)
- AC voltage starting with 0,1V up to 300V (30Hz up to 200MHz)
- AC current starting with 0,1mA up to 1A (30Hz up to 2MHz)
- voltage levels from -20 to +52dB (max. freq. 250MHz)
- Ohms starting from 5Ohm up to 1000MOhm

Let's start with the pictures.

Fastener for the front cover, on top the URI plate with a handle, front view, detailed view of the scale


Detailed view of the beautiful chicken head knobs.
main selector switch, DC ranges, AC ranges


The accessories are stored in the front cover.
overview, 30kV probe, holder for the 30kV probe, corroded banana plug


broken insulation of the 30kV probe, insulation debris, DC voltage probe


RF probe with different hooks, RF-pre-connector divider (plate 1, 2, 3)


Let's see what's inside.
On the right side of the ECC40 there is the voltage reference, a stabilizer tube STV 100/60Z II
Mains transformer, a corroded fuse (mains input terminal), power indicator lamp


back side, bottom side, untouched calibration trimpots, dual diode EB41 with a capacitor bank


nice connection joint, electrolytic capacitors, AEG electrolytic capacitors, vacuum tube socket


And here we are having all the rotary switches.
left ohms switch -  mid DC current switch - right DC voltage switch, left AC voltage switch - mid AC current switch - right ohms switch, wirewound resistor mounted on the main selector switch


precision resistors, main range selector switch, detailed view of the ohms range switch,


But how does it perform after all this years?
I took out my Fluke 3330B and did some measures. I used the Brymen BM869s for comparison.
I've warmed up the URI for about 10 minutes before starting the measuring.
And I did of course this null point calibration first as described in the manual.
Because the 3330B can do only DC, no AC measurements were taken.

Lets begin with DC voltage:
1V, 3V, 10V, 30V, 100V, 300V



Voltages are reading a bit low but I haven't checked yet, if they are within specifications.

Next the DC current ranges. The 3330B can do a max current of ca. 111mA, so I'm going to measure only up to the 100mA range.
100nA, 1µA, 10µA, 100µA, 300µA
1mA, 3mA, 10mA, 30mA, 100mA





Some of the DC current ranges are spot on, some are reading a bit high. The 1µA and 100nA range seems to have a problem (needle off the scale). Impressive for an instrument of that age.

Measuring my 10kOhm reference resistor:


I've attached a full scan of the manual here. The source can be found here.

I hope, you've enjoyed this teardown. Sorry for some of the blurry pictures. It seems, that the camera of my Z3 has come to its limits.

Please stay tuned for part five of this little series, the Rohde & Schwarz NF millivoltmeter UVN BN 12001.

Thank you for watching.

Edit:
I've added the scale in a better resolution (repeated my measures) and added the measuring of my 10kOhm reference resistor.

[med6753]

Echoes from a distant past

Part four - The Rohde & Schwarz Vacuum Tube Meter URI 1050BN

Edit:
Part one - Siemens Rel. send. 22b
Part two - The Two Transformers
Part three - The Rohde & Schwarz NGU laboratory power supply unit for vacuum tubes
Part four - The Rohde & Schwarz Vacuum Tube Meter URI 1050BN

Hello,

today I'd like to introduce the Rohde & Schwarz URI 1050BN vacuum tube meter which capable of measuring DC volts and currents, AC volts and currents and Ohms. The meter has been produced in the 50's and 60's of the 20th century. It has an impressive wide measurement range. It can measure:
- DC current starting with 2nA up to 1A
- DC voltage starting with 20mV up to 300V (30kV with the 30kV probe)
- AC voltage starting with 0,1V up to 300V (30Hz up to 200MHz)
- AC current starting with 0,1mA up to 1A (30Hz up to 2MHz)
- voltage levels from -20 to +52dB (max. freq. 250MHz)
- Ohms starting from 5Ohm up to 1000MOhm

......snip

Impressive and typical German over engineering. Separate rotary switches for each function. Only the Germans would come up with that and truth be told I love it.   

[Cerebus]

What you can tell from those traces is that the 'fake' references have much higher peak to peak noise over relatively short periods (minutes) than the genuine article.

Yes, that much is obvious. But if I were to take the real and fake and use them as a reference in a typical 4.5 or 5.5 digit DMM would I see much, if any, difference?

Tsk, you ought to be able to figure that out for yourself.   

One of the 'fake' references shows a 300uV jump at one point, 30ppm of a 10V reference, which would be 3 counts on a 100,000 count (5 1/2) digit meter or 0.3 counts on a 4 1/2 digit meter (nearly enough to push the last digit one way or the other). Rule of thumb says that noise-wise your reference should be 4 to 10 times better than the least significant digit, i.e. 0.25 to 0.1 digits peak to peak (1/6 that figure for RMS). So the 'fakes' would be OK on 3 1/2 digits, not really for 4 1/2 digits, right out of the running for 5 1/2 digits. Obviously we don't know the long term stability of these from those short graphs but I doubt that it's up to much.

[Specmaster]

Lets begin with DC voltage:
1V, 3V, 10V, 30V, 100V, 300V

Voltages are reading a bit low but I haven't checked yet, if they are within specifications.

These photos are clear example when the extra resolution is required, in order to see the true needle indication.

[med6753]

Speaking of VTVM's would love to find one of these. Plenty of the newer units on Ebay but this one dates to the 1950's. Not as fancy as the R&S but still very accurate.

[Carl_Smith]

Well, resistor is baked and coated in enamel and reinstalled.
I forgot I had a Chinese Uyue 946c hotplate hiding on my shelf, so it was put to good use.

Yesterday I was going to suggest that if you had a 3D printer with a heated bed you could use that to bake the resistors.  Throw them on the bed and maybe put a small box or something over them to hold in some heat.  But by the time I got to the end of the thread I forgot to reply.

[mansaxel]

Part four - The Rohde & Schwarz Vacuum Tube Meter URI 1050BN

Very impressive. As I've posted about earlier, I've got my Marconi VTVM from roughly the same period on the bench for a run through after  recapping it, so this hits right home.  The R&S has the Marconi beat with an order of magnitude in build quality.  And, it's quirky in a way that makes sense!

Now, if we start comparing the 410B and the URI, then it feels closer. Except in current, because that was never a thing in anglo-american VTVM builds.

[capt bullshot]

Maybe you remember I've got fake AD587 references from china and somewhat later real AD587UQ from Mounty.
...

To address some of the criticism and questions:
- I don't care about head slapping physics teachers, though they're right of course
- This is not a proper voltnut setup at all, it's just fun with TEA. I do know the measurements depend on both the characteristics of the used DMMs and the references itself, a better way would be to use a multiplexer and a previously characterized DMM. And I do not log the ambient temperature which appears to have quite an influence on the references.

Here's the same plot over somewhat longer time span:



What can we see here:

Genuine reference 1 (blue) and 2 (red) have different short term noise levels, but quite similar long term drift. I'll have to investigate whether the noise is inherent to the HP34401s or the particular reference.
Both fake references (green and yellow) have well visible higher noise level, but their long term drift is quite different in nature than the original ones. The green one has some periods of "jumping" between two values - this also has to be investigated if it's introduced by the reference or the DMM.

Since I'm not logging the ambient temperature, this is guesswork: The genuine references apparently are less stable over temperature while the others rather appear to drift over time and have less temperature dependency.

The fakes are not factory rejects, they're most probably bandgap (instead of buried zener) references with compatible pinout and were relabeled. One can easily determine this by looking at the adj. pin voltage level and adjustment range. Anyway, to see the differences in noise level and drift is interesting, they have totally different characteristics. In comparison to the 34401A internal reference and the Fluke 5100 (that I've used to check the DMMs before) they're "meh". Otherwise, they're all within +/- 110uV of their (arbitrarily set) initial value over this experiments time range, which equals 22ppm - comfortably good enough to check (not calibrate or adjust) 4 1/2 and 5 1/2 digit DMMs, once their initial value is known and they're used at a close enough temperature.

[mnementh]

IMHO, Without knowing/subtracting the response of the 4 different meters over that time as opposed to measuring with the same meter/multiplexer, it's pretty hard to accurately characterize anything at this resolution. It appears the "fakes" have aboot 2x-3x the actual drift of the "genuine" ones, at least as compared against the nexus of normalization at ~11:40.

mnem
 

Yeah, but picking an arbitrary time point to determine 'drift' maketh no logical sense. For instance, if the left of the graph is the actual turn-on time then the 'fake' references would seem to have less drift overall as determined by the difference between maxima and minima for each trace.  Looking at both, sometimes the 'fake' are better than the 'real' depending on the timescale you evaluate drift over. There's a reason that this kind of drift is normally evaluated by looking at Allan variance.

What you can tell from those traces is that the 'fake' references have much higher peak to peak noise over relatively short periods (minutes) than the genuine article.

Also, capt bullshot would have received a glancing blow to the back of his head from my school physics teacher for having failed to label neither the axes nor title the graph. 

Yeah, but that "nexus" is aboot as far back as you can start reading with the test conditions being the same. That's the only reason I chose to start reading at that point; agreed it's not the best reason either, but not absolutely arbitrary. 

mnem
      ^{https://xkcd.com/833/}

of course, there's a XKCD for that. 

[Neper]

Speaking of VTVM's would love to find one of these. Plenty of the newer units on Ebay but this one dates to the 1950's. Not as fancy as the R&S but still very accurate.

I happen to own a close relative of yours, a WV-97A. When it arrived here, the ohmmeter battery had leaked and much of the rear wall had the usual white corrosion. I was able to scrape off most of it but it still has a very unpleasant sour smell when it's open, which has so far kept me from tackling its various problems.

Unfortunately it is more than a little off in all ranges and rather inconsistently so. I have my doubts if the meter movement still is original. Note the cutout at the bottom of the scale. It just doesn't look right.



As an interesting aside, it has been used at or sold by the Société Belge Radio-Electrique (SBR), at the time Belgium's biggest maker of radios and radio equipment:

[factory]

Speaking of VTVM's would love to find one of these. Plenty of the newer units on Ebay but this one dates to the 1950's. Not as fancy as the R&S but still very accurate.

There are two WV-87A on ePay and one later B version.

https://www.ebay.com/itm/324825230533


https://www.ebay.com/itm/154667805983


David

[factory]

Part four - The Rohde & Schwarz Vacuum Tube Meter URI 1050BN

Very impressive. As I've posted about earlier, I've got my Marconi VTVM from roughly the same period on the bench for a run through after  recapping it, so this hits right home.  The R&S has the Marconi beat with an order of magnitude in build quality.  And, it's quirky in a way that makes sense!

Now, if we start comparing the 410B and the URI, then it feels closer. Except in current, because that was never a thing in anglo-american VTVM builds.

You would need a separate VTVM for each, hp 412A or hp 425A for DC current and hp 400D/H/L with the shunt resistor set, or current probe for AC current.

David

[BU508A]

Lets begin with DC voltage:
1V, 3V, 10V, 30V, 100V, 300V

Voltages are reading a bit low but I haven't checked yet, if they are within specifications.

These photos are clear example when the extra resolution is required, in order to see the true needle indication.

You got a point here. I've added some close-up pictures of the scale. They should be readable now.
Added also the measuring of my 10kOhm reference resistor which I had forgotten in the first turn.

[med6753]

Speaking of VTVM's would love to find one of these. Plenty of the newer units on Ebay but this one dates to the 1950's. Not as fancy as the R&S but still very accurate.

There are two WV-87A on ePay and one later B version.

https://www.ebay.com/itm/324825230533


https://www.ebay.com/itm/154667805983


David

Thanks for that. My Evil bay search must be broken. Anyway, I messaged the seller of the one with all the dirt/corrosion. I asked if he could provide some pictures of the interior. If it's decent I can deal with the exterior and that will be my next project. 

[mansaxel]

Part four - The Rohde & Schwarz Vacuum Tube Meter URI 1050BN

Very impressive. As I've posted about earlier, I've got my Marconi VTVM from roughly the same period on the bench for a run through after  recapping it, so this hits right home.  The R&S has the Marconi beat with an order of magnitude in build quality.  And, it's quirky in a way that makes sense!

Now, if we start comparing the 410B and the URI, then it feels closer. Except in current, because that was never a thing in anglo-american VTVM builds.

You would need a separate VTVM for each, hp 412A or hp 425A for DC current and hp 400D/H/L with the shunt resistor set, or current probe for AC current.

David

Or the 428b. Which I have!

[mnementh]

Thanks for that. My Evil bay search must be broken. Anyway, I messaged the seller of the one with all the dirt/corrosion. I asked if he could provide some pictures of the interior. If it's decent I can deal with the exterior and that will be my next project. 

Uh-oh... I knew you'd been clean a little too long; feelin' a need to spray sumptin', aren'cha...? 

mnem
"Lock up the wimmen & hide the fried chicken... med's on the prowl..." 

[factory]

I found this Systron Donner time code gen/reader on the Bay earlier in the week, the parcel arrived on Friday with the usual comments of "not another grey box" wrong they were as it's vomit color. 
For a change it was very well packed, wrapped in card, foam wrapped on front panel, then bubble wrap and in a large box of shredded paper. 

Quick look that evening found a shattered fuse for the HV supply and 2A fuses fitted for the mains (values marked for 110V) but has been changed to 230V in the past.
Today I found a 150mA (no 125mA in stock) fuse and two 1A fuses for the mains input and gave it a try, it seems to mostly working, but most of the tubes are very knackered and the days didn't change between 23:59:59 & 00:00:00, it has quite a noisy fan too.




David

[Cerebus]

I found this Systron Donner time code gen/reader on the Bay earlier in the week, the parcel arrived on Friday with the usual comments of "not another grey box" wrong they were as it's vomit color. 

Having my own Systron-Donner pulse generator to get the full horror of the colour first hand I must disagree. My colour card says "Fleet Street pub ceiling, circa 1972".

[Cubdriver]

Yeah, S-D’s “puke yellow #4” is certainly the worst enclosure color I’ve come across thus far.  Not sure who picked that one, but they must have been at least partially color blind!  Blechh!

-Pat

[mnementh]

Were they actually made that color or just a popular color choice of the era exacerbated by the vagaries of time and elemental exposure...?

mnem
 

[Cerebus]

No, they really are that horrible a colour, originally and intentionally.

The paintwork on mine is pristine (and of high quality) and the same colour where it's protected from the environment as on the exposed bits. It's a smooth uniform colour all over, the same colour that someone actually chose to make it.

When I first got it my first thought was exactly yours, "God this has suffered the ravages of time, I'm going to be scrubbing this muck off for ever!", because I couldn't believe that someone would deliberately paint it the colour of something that had been screwed to the wall between a urinal and a condom machine  in a very smoky pub for 20 years. But proper examination proved that they did.

At least they chose a highly durable pigment. Hmm, I've just had the terrifying thought that cadmium dichromate is (a) highly durable, (b) about the right colour. They couldn't, they wouldn't, use that as a pigment, would they? 

[Robert763]

I found this Systron Donner time code gen/reader on the Bay earlier in the week, the parcel arrived on Friday with the usual comments of "not another grey box" wrong they were as it's vomit color. 
For a change it was very well packed, wrapped in card, foam wrapped on front panel, then bubble wrap and in a large box of shredded paper. 

Quick look that evening found a shattered fuse for the HV supply and 2A fuses fitted for the mains (values marked for 110V) but has been changed to 230V in the past.
Today I found a 150mA (no 125mA in stock) fuse and two 1A fuses for the mains input and gave it a try, it seems to mostly working, but most of the tubes are very knackered and the days didn't change between 23:59:59 & 00:00:00, it has quite a noisy fan too.
<SNIP>

David

I hope the offer was a lowball...
They had listed it as used which means fully working regardless of what they put in the description. If you are not happy with it do a return through ebay or get a partial refund.

The "days" not incrementing may be because it is set as Identification number (ID) rather than days.

[tautech]

Pokes TEA thread with OT just to see if there's anyone out there ?

Nearly record downpour event in August created a few small landslides which is just nature doing its thing but one came outta the bush and skittled some of our bush block reserve fencing ! 

Wouldn't be a problem except at that time of year and moment laid eyes on it knew what a tragi-mess it would turn into. 
First pic shows some of the BS we had to go through with a snatch block anchored to a tree and ropes fed under the tractor onto Larry Minor's little Fiat crawler.
All that just to replace one broken strainer then some more hours to get all the wires back on it to keep stock from the reserve. 
The tidy up can wait until Jan/Feb mid summer !

[med6753]

Pokes TEA thread with OT just to see if there's anyone out there ?

Nearly record downpour event in August created a few small landslides which is just nature doing its thing but one came outta the bush and skittled some of our bush block reserve fencing ! 

Wouldn't be a problem except at that time of year and moment laid eyes on it knew what a tragi-mess it would turn into. 
First pic shows some of the BS we had to go through with a snatch block anchored to a tree and ropes fed under the tractor onto Larry Minor's little Fiat crawler.
All that just to replace one broken strainer then some more hours to get all the wires back on it to keep stock from the reserve. 
The tidy up can wait until Jan/Feb mid summer !

I see you have very wet and muddy Springtime too.

For some reason I have a hard time wrapping my head around "Jan/Feb mid summer" especially when outside temperature is currently -1 C. 

Edit.....typical Jan/Feb in these parts.