Test Equipment Anonymous (TEA) group therapy thread

[med6753]

The 7904 has been going for a few hours and it was time to throw some high frequencies at it. Impressive. This CRT is sharper than the old one. 

[mnementh]

Yep, RTFM is always a revelation. 

Remember when almost all electronics actually had a manual, with a Principles/Theory of Operation section? 

mnem
Yeah, I remember when cars didn't know anything too.

[worsthorse]

So I am looking at my test bench, which is almost completely comprised of second (or third or fourth) hand test equipment. It works okay, in the sense that the measuring stuff measures and the generating stuff generates, which often suffices in my two-significant-digit world.  But it makes me a little crazy because when something is a little off, I never really know whether it is my instruments or the circuit under test.

(Yes I know, one never knows but you know what I mean, knows well enough.  )

And I can do a little home calibration as I have the DMMCheckPlus and a decent 10MHz frequency standard, but...

So I am thinking of getting my one of my frequency counters, maybe the 5328A, and one of my DMMs, the 8840A, calibrated and then working my way through the other gear so that at least it mostly agrees with each other.   Of course, it has been forty years since I purchased calibration services, so I have no idea what it costs...

But am I crazy? Wait, don't answer that until I finish please.  Am I crazy to try to get a baseline I can use to establish a minimal level of credibility on my bench? Am I descending into some new form of nuttery? What do you all do?

[worsthorse]

Yep, RTFM is always a revelation. 

Remember when almost all electronics actually had a manual, with a Principles/Theory of Operation section? 

mnem
Yeah, I remember when cars didn't know anything too.

Yeah... like the 8840A manual I am reading right at this moment. 

[mnementh]

(SNIP)
But am I crazy? Wait, don't answer that until I finish please.  Am I crazy to try to get a baseline I can use to establish a minimal level of credibility on my bench? Am I descending into some new form of nuttery? What do you all do?

In FLUKE we trust. 

mnem
Questions? See above.

[nixiefreqq]

So I am looking at my test bench, which is almost completely comprised of second (or third or fourth) hand test equipment. It works okay, in the sense that the measuring stuff measures and the generating stuff generates, which often suffices in my two-significant-digit world.  But it makes me a little crazy because when something is a little off, I never really know whether it is my instruments or the circuit under test.

(Yes I know, one never knows but you know what I mean, knows well enough.  )

And I can do a little home calibration as I have the DMMCheckPlus and a decent 10MHz frequency standard, but...

So I am thinking of getting my one of my frequency counters, maybe the 5328A, and one of my DMMs, the 8840A, calibrated and then working my way through the other gear so that at least it mostly agrees with each other.   Of course, it has been forty years since I purchased calibration services, so I have no idea what it costs...

But am I crazy? Wait, don't answer that until I finish please.  Am I crazy to try to get a baseline I can use to establish a minimal level of credibility on my bench? Am I descending into some new form of nuttery? What do you all do?

for frequency WE didn't bother with a cal service.  instead we bought a rubidium standard to compare to all the ocxo's in the basement.

but then you wonder if maybe your rubidium is wacky. (not likely, but possible).

so then you buy a loran tracking receiver to compare to the rubidium.  but when the potus writes an executive order and turns off the entire loran network you buy a gpsdo.  but what if it gets hit by lightning?  so you by a backup gpsdo.

am still looking for a cesium beam standard in case the gps network gets attacked by aliens.

madness......total madness.

[med6753]

(SNIP)
But am I crazy? Wait, don't answer that until I finish please.  Am I crazy to try to get a baseline I can use to establish a minimal level of credibility on my bench? Am I descending into some new form of nuttery? What do you all do?

In FLUKE we trust. 

mnem
Questions? See above.

"Trust, but verify". I've seen a few Flukes that were NOT trustworthy and needed to be beat back into shape. 

[beanflying]

Speaking of Whirry Little Flying Things...

I'm currently dismantling my first FPV/Aerial Photography rig; getting rid of the chassis as I know I'll never rebuilt that prehistoric thing and it takes up more space than the last 5 I've built put together.

This one little piece... the PDB... weighs twice as much as the last FPV/AP quad I built, and that's all-up flying weight. 

mnem
flip!!!

Clearly you NEED to add a Mavic to your fleet 

[beanflying]

So I am looking at my test bench, which is almost completely comprised of second (or third or fourth) hand test equipment. It works okay, in the sense that the measuring stuff measures and the generating stuff generates, which often suffices in my two-significant-digit world.  But it makes me a little crazy because when something is a little off, I never really know whether it is my instruments or the circuit under test.

(Yes I know, one never knows but you know what I mean, knows well enough.  )

And I can do a little home calibration as I have the DMMCheckPlus and a decent 10MHz frequency standard, but...

So I am thinking of getting my one of my frequency counters, maybe the 5328A, and one of my DMMs, the 8840A, calibrated and then working my way through the other gear so that at least it mostly agrees with each other.   Of course, it has been forty years since I purchased calibration services, so I have no idea what it costs...

But am I crazy? Wait, don't answer that until I finish please.  Am I crazy to try to get a baseline I can use to establish a minimal level of credibility on my bench? Am I descending into some new form of nuttery? What do you all do?

DMM Checkplus is a great 'sanity checker' only team that with a cheap GPSDO and be happy with them.

OR

I recently spent a chunk of change and sent my two 6 1/2 digit meters to Keysight. That 'pair' is now being used systematically to go over the rest of the fleet with my GPSDO being used for a frequency reference. Why send a pair away? It was to improve the certainty of the gear I am now calibrating which is close to if not better than the reference meters and GPSDO. This will bring the entire fleet close to Cal and more than good enough for what I want to do with it. Next year sometime I would most likely only send one of them off for Cal but take a careful set of measurements on the other before it leaves then repeat the cycle on the rest of the gear when it gets back.

[bitseeker]

Am I crazy to try to get a baseline I can use to establish a minimal level of credibility on my bench? Am I descending into some new form of nuttery? What do you all do?

I appoint devices to be my in-house standards. They're generally the most stable one in a category or ones that I have the most confidence in. All the others are compared to the designated standards and either brought in line or offset noted. If I buy a new device with a known calibration or can borrow a standard with a known history, I'll use it to validate the in-house standard.

For example, my Agilent 34401A is my DMM standard. When I got a new U1282A, I used its in-cal status to sanity check the 34401A on all functions and ranges. Each time one of the USA Cal Club voltage and resistance refs get around to me, I check them using the 34401A to see how much it has changed.

For example, the past few years the 34401A has consistently been about 200µV high at 10V. Have I adjusted it? Nah. I'm OK with having a little more potential than everyone else. It's close enough at that resolution to adjust my power supplies, lower-res DMMs, etc.

For frequency, if you don't want to have GPSDO-based central frequency source (or don't have external clock on all your gear), you can still get one of the inexpensive GPS modules to tune up a frequency counter pretty well. That's still on my to-do list.

[BravoV]

..... GPSDO-based central frequency source ...... That's still on my to-do list.

What ? A TEA priest that doesn't have a GPSDO ? How could you ?

[med6753]

Am I crazy to try to get a baseline I can use to establish a minimal level of credibility on my bench? Am I descending into some new form of nuttery? What do you all do?

I appoint devices to be my in-house standards. They're generally the most stable one in a category or ones that I have the most confidence in. All the others are compared to the designated standards and either brought in line or offset noted. If I buy a new device with a known calibration or can borrow a standard with a known history, I'll use it to validate the in-house standard.

For example, my Agilent 34401A is my DMM standard. When I got a new U1282A, I used its in-cal status to sanity check the 34401A on all functions and ranges. Each time one of the USA Cal Club voltage and resistance refs get around to me, I check them using the 34401A to see how much it has changed.

For example, the past few years the 34401A has consistently been about 200µV high at 10V. Have I adjusted it? Nah. I'm OK with having a little more potential than everyone else. It's close enough at that resolution to adjust my power supplies, lower-res DMMs, etc.

For frequency, if you don't want to have GPSDO-based central frequency source (or don't have external clock on all your gear), you can still get one of the inexpensive GPS modules to tune up a frequency counter pretty well. That's still on my to-do list.

I do similar with my DMM's. Of the 3.5 and 4.5 digit DMM's the Fluke 8050A is generally the most accurate and most stable therefore it's my "Bench Standard". I use it to calibrate my home built voltage references which in turn calibrate/check my other 3.5 and 4.5 digit DMM's.

My 5.5 digit DMM's are more complex. Siglent SDM 3055 and Fluke 8810A. Both of them absolutely require minimum 24 hour warm up for best accuracy. The 8810A drifts the most but settles down. I use two AD584-M references to check them. The 8810A after 24 hours is typically dead on. The SDM 3005 generally reads 0.0002 to 0.0003 volts low. In the overall scheme of things that don't add up to a hill of beans so I just note it.

I haven't ventured into time nuttery territory (yet  ). Besides, I'm retired and got all the time in the world.     

[0culus]

The 7904 has been going for a few hours and it was time to throw some high frequencies at it. Impressive. This CRT is sharper than the old one. 

That does indeed look very nice!  Hope you are able to get the gremlins out and enjoy the 'scope. My 7904A is such a joy to use, but I wish they hadn't abandoned the illuminated vertical and horizontal mode switches that yours has.

[mnementh]

Speaking of Whirry Little Flying Things...

I'm currently dismantling my first FPV/Aerial Photography rig; getting rid of the chassis as I know I'll never rebuilt that prehistoric thing and it takes up more space than the last 5 I've built put together.

This one little piece... the PDB... weighs twice as much as the last FPV/AP quad I built, and that's all-up flying weight. 

mnem
flip!!!

Clearly you NEED to add a Mavic to your fleet 

You know what's funny... When I started tinkering around with multirotors, what I was trying to build was something exactly like a Mavic, but the technology didn't exist yet in the hobbyist space. It was my driving passion, and I built more and more sophisticated little drones with better and better FCs & waypoint software, until I discovered how fun the little airframes I was letting fly themselves were to fly for myself. 

Then came the drive to simplify and build more & more high-performance, fully manual quadcopters to crash & build & crash again.    Now I really don't care that much about Aerial Cinematography; there are dozens of $150 folder clones that do everything I ever dreamt of back then and more, and in higher definition. 

mnem
If you're not crashing, you aren't really flying.

[bitseeker]

..... GPSDO-based central frequency source ...... That's still on my to-do list.

What ? A TEA priest that doesn't have a GPSDO ? How could you ?

Well, technically, I have a GPS module and several OCXO. So... it's yet another to-do item.

[bitseeker]

I haven't ventured into time nuttery territory (yet  ). Besides, I'm retired and got all the time in the world. 

Good one, med!

[med6753]

I know it's a day early.

"Down with the British!" 

[Specmaster]

When it comes to checking the calibration on my meters, I use a DC voltage checker of ebay, ADMxxx I forget the numbers but I think its 784. I check the meters for DC accuracy against that and my 6.5 DMMs are within 10 to 17 uV of each other, for DC current I use a Mastech calibrator which will provide upto 24mA in steps,  ohms I have some known resistors of 0.5% AC I just use mains voltage.

Then I use the same again on my 5.5, 4.5 and 3.5 DMMs and I'm very happy with the results on all of them and of course the 3.5 meters never disagree more than the last digit flickering between 2 digits so I still take comfort from that. That's as far down that rabbit hole as I intend to go, good enough for my work. My car is supposed to go 137mph but do need to check it, no[emoji4]

Sent from my POT-LX1 using Tapatalk

[bd139]

I know it's a day early.

"Down with the British!" 

https://youtu.be/tX5ZRE26YWM

 

[med6753]

I know it's a day early.

"Down with the British!" 

https://youtu.be/tX5ZRE26YWM

 

FUCK YEA! 

[beanflying]

I know it's a day early.

"Down with the British!" 

Just hope your Muppet 'in charge' gets laryngitis and ..... rest of comment removed but consider it grossly offensive to the size of his ..... (lets say Ego)

Vive la révolution 

[bd139]

something has been bothering me about my C channel upgrade to the hp 5334b.

looked again at my pictures and something appears to be missing.

seems i forgot to put  half the diodes in the peak detector circuit. (but it works anyway)

puzzled over it for quite a while and then decided it was time for drastic measures.

RTFM!!!

I think you only need half the diodes in one side of things so that might make sense. I can't remember if it's the peak detector or limiter.

[tggzzz]

Some tants just have a longer leg on the positive, which is a bastard if leg has clipped short for some reason as you then have a 50/50 chance of getting it right  Why cant they all use a common standard of marking that is good across all kinds of polarised caps, oh of stupid old me, that too fecking logical that's why 

Yeah totally agree. This one really gets me annoyed. I notice that X7R SMD ceramic caps are dirt cheap now the supply chains have cleared some of the backlog so I've started replacing tants with them instead. Cheaper, not polarised and even lower ESR.

Note that the capacitance is a function of the DC voltage; in many cases at the rated voltage the capacitance has fallen by 80%-90% - so derate more than a little.

In some cases, lower ESR can result in instability; it is a case of RTFM for the surrounding circuit.

Didn't I just say that? *Goes back to revise his post with even more pessimistic figures* And that? 

Yes, you did mention derating, but I hadn't got that far through the list of unread messages.

No, ISTR you only mentioned derating to 25%, and I note that your last change was made after I posted derating by 80%-90%, i.e. to 10%-20%

[med6753]

Gee, I don't feel like doing squat today. And here I sit in a t-shirt and skivvies. 

[mnementh]

I know it's a day early.

"Down with the British!" 

https://youtu.be/MZsEl3QIs38

*sigh* Garner was just a punk kid... and McQueen too.  Remember when it was still okay have heroes who used their brains?

mnem
*suddenly feeling very, very old*