Test Equipment Anonymous (TEA) group therapy thread

[grizewald]

Now if only I could get a GPIB adapter for my 7075...

https://www.equipnet.com/auctions/catalog/uk-rf-testing-sealed-bid/1096/?AuctionSearch=7075

Particularly the first lot is as close as you will get

Bloody hell! There's a whole 11 7075 meters there in two lots!

On eBay, there's a 7075 GPIB interface, but the seller is Radwell and they want over £120 for it. No way.

It might actually be fun to create an Arduino Mega 2560 - BCD controller interface.

[Kosmic]

Sometime ago I asked a similar question about the LM399 Vrefs in my 34970A's which only got a might be worth it response from a few of the Metrology heads https://www.eevblog.com/forum/metrology/hp-agilent-34970a-precision-logging-thread/msg1377876/#msg1377876

Keeping direct air movement away would be more important than insulation IMO so consider a dome over it without the insulation and let the temperature sit where it was designed. For those without a 3D printer https://www.amazon.co.uk/Assorted-Fillable-Plastic-Surprise-Easter/dp/B01N9ZM9SK for those who sensibly have one you know what to do 

LM399 is different since it has it's own oven and air draft protector built in (you can actually buy the chip without the white plastic cover). The only instrument I seen encapsulating the LM399 is the Valhalla 2720GS where 2 LM399 are inside an oven. They are probably running the 1st oven a bit cooler to compensate.

Even with it being ovenised there is still drift due to draughts on the can and legs, plenty of info on that and including the LTX1000. In your case I would be concerned that insulating rather than just stopping draughts will push the component temperature higher screwing with the reference circuit's voltage/calibration. You might find a more stable but out of calibration instrument is the result. Worth asking as a seperate thread in Metrology for some more experienced feedback.

Make sense for the LTZ1000 since the can is exposed. I guess the LM399 was too sensible since they are mostly selling the chip with the plastic draft protector. So I don't think adding a second draft protector on top of the original one will change anything.

[Kosmic]

If you have a VISA compatible gpib adapter I can send you my software. You configure via .xml file and it dump the data in .csv. I'm building the UI right now. Will eventually support graph, filtering and etc ..

I don't have such an adapter unfortunately, for two reasons: they cost way too much money for what they are; they use drivers which will only run on Windows and I won't use Windows on my machines at home.

Keysight has a linux driver for the 82357B 

Was using a Prologix adapter a while ago and I was trying to write my own software and it was just not fun. Switched to Keysight 82357B and everything changed. The visa drivers make it super easy to interface with in your own software / scripts and it support 3rparty software (Tektronix, Lecroy, NI).

[grizewald]

Agreed. The temperature of the transfo is concerning. I'm wondering if it was always like that. This guys thought it was a good idea to add a heatsink and fan on top of the transfo.

None of my Solartron meters with the linear supplies have any hum from the transformers to indicate they are getting tired and I'd say that the heat from these transformers is quite normal. I'd seen pa4tim's cooler mod, but can't really see the need. I'm pretty sure that the case is meant to act as a heat sink for the transformer. Mine never exceeded the 42°C in the thermal image, but exceeded that temperature fairly quickly when I had the top of the case off. Also, I'm allergic to fan noise.

I posted some comparaison on the Prema 5017 thread (Solartron 7061 vs Prema 5017 vs HP 34401a).

That's great data! I think I'm seeing similar amounts of noise on my 7061. I still think that over 150nV noise is a poor show for a 7.5 digit meter. If that's the real noise floor, what's the point of having more than four digits?

They definitely did a effort to move the diode away from the board for some reason. You can disable auto zero via gpib. I remember running some tests with auto disabled and did not see a huge difference. Technically it help with drift.

I'm still confused by the auto zero function. Where is this "thermal drift" coming from? Why do they need the auto zero function in these meters when they didn't need it in the 7075? How is it that once my 7075 has actually warmed up and stabilised, it shows 0.000000 with shorted inputs and rarely moves more than +/- 1μV from that point?

One other tool I'll be building to help look at the noise levels on all my precision meters is a xdevs.com KX LTZ1000A reference. I have all the parts now thanks to Mouser's incredible service. All I'm waiting for is the PCBs from OSHPark and some bismuth/tin super low melting point solder paste from China.

Cool, what is going to be your resistor setup ?

R3: 120R
R4: 1K
R5: 12295.5R
R6, R7: 68.1K

The selection is mostly based on "what I could get hold of", tempered with advice from the mega-thread about what values would be acceptable for each function. All of the resistors are 0.01% tolerance and 5ppm/C or better TCR. I'd like to get ones with a better TCR, but this is the compromise I could get from stock and build a KX reference now instead of in a year's time.

[med6753]

The above dissertations is why I won't go above 5.5 digits. 

I would fall into that rabbit hole and never come out. 

[Kosmic]

I posted some comparaison on the Prema 5017 thread (Solartron 7061 vs Prema 5017 vs HP 34401a).

That's great data! I think I'm seeing similar amounts of noise on my 7061. I still think that over 150nV noise is a poor show for a 7.5 digit meter. If that's the real noise floor, what's the point of having more than four digits?

I should run the same test in 7.5 digits. Noise might be lower since integration is longer. I was mostly trying to compare it to the 34401a and ended up disappointed  The 34401a is a really good meter.

Also, I understand now why the Prema 5017 come with some special filter functions 

[beanflying]

Sometime ago I asked a similar question about the LM399 Vrefs in my 34970A's which only got a might be worth it response from a few of the Metrology heads https://www.eevblog.com/forum/metrology/hp-agilent-34970a-precision-logging-thread/msg1377876/#msg1377876

Keeping direct air movement away would be more important than insulation IMO so consider a dome over it without the insulation and let the temperature sit where it was designed. For those without a 3D printer https://www.amazon.co.uk/Assorted-Fillable-Plastic-Surprise-Easter/dp/B01N9ZM9SK for those who sensibly have one you know what to do 

LM399 is different since it has it's own oven and air draft protector built in (you can actually buy the chip without the white plastic cover). The only instrument I seen encapsulating the LM399 is the Valhalla 2720GS where 2 LM399 are inside an oven. They are probably running the 1st oven a bit cooler to compensate.

Even with it being ovenised there is still drift due to draughts on the can and legs, plenty of info on that and including the LTX1000. In your case I would be concerned that insulating rather than just stopping draughts will push the component temperature higher screwing with the reference circuit's voltage/calibration. You might find a more stable but out of calibration instrument is the result. Worth asking as a seperate thread in Metrology for some more experienced feedback.

Make sense for the LTZ1000 since the can is exposed. I guess the LM399 was too sensible since they are mostly selling the chip with the plastic draft protector. So I don't think adding a second draft protector on top of the original one will change anything.

As you start getting down into the thermal EMF and noise leg to copper pcb junctions matter too.


Yes Alice we are in the Rabbit Hole 

[Kosmic]

The above dissertations is why I won't go above 5.5 digits. 

I would fall into that rabbit hole and never come out. 

Come on, it's tons of fun. And beside, I found the bottom of the hole, doesn't go deeper than 8.5 digits 

[mnementh]

@med: Are you kidding...? This is some primo OPVN right here.  Here, have some popcorn... 

mnem
As long as bean leaves that de-nutting knife at home we should all be okay...

[Kosmic]

Sometime ago I asked a similar question about the LM399 Vrefs in my 34970A's which only got a might be worth it response from a few of the Metrology heads https://www.eevblog.com/forum/metrology/hp-agilent-34970a-precision-logging-thread/msg1377876/#msg1377876

Keeping direct air movement away would be more important than insulation IMO so consider a dome over it without the insulation and let the temperature sit where it was designed. For those without a 3D printer https://www.amazon.co.uk/Assorted-Fillable-Plastic-Surprise-Easter/dp/B01N9ZM9SK for those who sensibly have one you know what to do 

LM399 is different since it has it's own oven and air draft protector built in (you can actually buy the chip without the white plastic cover). The only instrument I seen encapsulating the LM399 is the Valhalla 2720GS where 2 LM399 are inside an oven. They are probably running the 1st oven a bit cooler to compensate.

Even with it being ovenised there is still drift due to draughts on the can and legs, plenty of info on that and including the LTX1000. In your case I would be concerned that insulating rather than just stopping draughts will push the component temperature higher screwing with the reference circuit's voltage/calibration. You might find a more stable but out of calibration instrument is the result. Worth asking as a seperate thread in Metrology for some more experienced feedback.

Make sense for the LTZ1000 since the can is exposed. I guess the LM399 was too sensible since they are mostly selling the chip with the plastic draft protector. So I don't think adding a second draft protector on top of the original one will change anything.

As you start getting down into the thermal EMF and noise leg to copper pcb junctions matter too.

Off course since the input leads are in Kovar. Create a thermocouple with copper 

[med6753]

The above dissertations is why I won't go above 5.5 digits. 

I would fall into that rabbit hole and never come out. 

Come on, it's tons of fun. And beside, I found the bottom of the hole, doesn't go deeper than 8.5 digits 

I don't understand half the stuff you guys are talking about. 

[beanflying]

Sometime ago I asked a similar question about the LM399 Vrefs in my 34970A's which only got a might be worth it response from a few of the Metrology heads https://www.eevblog.com/forum/metrology/hp-agilent-34970a-precision-logging-thread/msg1377876/#msg1377876

Keeping direct air movement away would be more important than insulation IMO so consider a dome over it without the insulation and let the temperature sit where it was designed. For those without a 3D printer https://www.amazon.co.uk/Assorted-Fillable-Plastic-Surprise-Easter/dp/B01N9ZM9SK for those who sensibly have one you know what to do 

LM399 is different since it has it's own oven and air draft protector built in (you can actually buy the chip without the white plastic cover). The only instrument I seen encapsulating the LM399 is the Valhalla 2720GS where 2 LM399 are inside an oven. They are probably running the 1st oven a bit cooler to compensate.

Even with it being ovenised there is still drift due to draughts on the can and legs, plenty of info on that and including the LTX1000. In your case I would be concerned that insulating rather than just stopping draughts will push the component temperature higher screwing with the reference circuit's voltage/calibration. You might find a more stable but out of calibration instrument is the result. Worth asking as a seperate thread in Metrology for some more experienced feedback.

Make sense for the LTZ1000 since the can is exposed. I guess the LM399 was too sensible since they are mostly selling the chip with the plastic draft protector. So I don't think adding a second draft protector on top of the original one will change anything.

As you start getting down into the thermal EMF and noise leg to copper pcb junctions matter too.

Off course since the input leads are in Kovar. Create a thermocouple with copper 

This is worth a read https://xdevs.com/doc/Fluke/720A/doc/JW_EDN_p3.pdf

[Kosmic]

I'm still confused by the auto zero function. Where is this "thermal drift" coming from? Why do they need the auto zero function in these meters when they didn't need it in the 7075? How is it that once my 7075 has actually warmed up and stabilised, it shows 0.000000 with shorted inputs and rarely moves more than +/- 1μV from that point?

Everything drift. They are probably compensating differently on the 7075. But I didn't see any ill effects of the auto zero on the 7061.

[mnementh]

Fuck those inconvenienced electrons. If I can get up every morning and go to work, so can they. 

mnem
*unrepentant*

[med6753]

I think I'll go play with the 535A. That I can get my head around and comprehend although getting my arms around it is impossible. 

[mnementh]

Awww... go give it a nice warm hug. It has the warm part already sorted for ya. 

mnem
*tzzzt*

[WastelandTek]

Keysight has a linux driver for the 82357B 

$738 !?!?!?!?!!!

[beanflying]

Think I will go play with timber. If it misbehaves due to Temperature, plane it, sand it or use a bigger Hammer 

[Kosmic]

Keysight has a linux driver for the 82357B 

$738 !?!?!?!?!!!

Paid 60$ for mine (used). and yes it's an original and not a clone 

[bitseeker]

Ok just got home. Today’s haul:

3400A meter is peeling badly And it has the old style line connector so will require some work. I know someone who has a 3400A meter floating around which will go in it if I can lever it off them for a decent price  . As for the rest of it as yet unknown. Bolometer and chopper are probably fecked knowing my luck. Worst case I paid less than the feet are worth for it.

...

Scope tear down coming later. It’s a plain 2445 so no nasty bits inside in theory. Will see. Sure there’s RIFAs in there.

Amazingly, we didn't have either in the POI. Added.

[bitseeker]

Am I missing something here? someone thinks a 1960's HP 6269A (40V 50A PSU) is worth nearly £500 (plus almost £1/kg for the courier). 

eBay auction: #184164186009

P.S. Sticking a later HP badge on the front will not fool me.

Badge inflation!

(I guess it's better than no badge at all.)

[bitseeker]

Just realized, many of TEA regulars here, own Tek 24x5 A/B/plain, aren't we ?

I'm a mere observer here, but I have my admission pass 

Alas, thus far, I only have a 454 and a 2215A. One day...one day.

[bitseeker]

When noise, and thermal emf is involve you need more than a spot check. Logging the same ref (or simply a short) for 2 days with and without isolation would probably be interesting.

...

But I will be recording some long term statistics from the 7061 as soon as I have that all done. Now if only I could get a GPIB adapter for my 7075...

If you have a VISA compatible gpib adapter I can send you my software. You configure via .xml file and it dump the data in .csv. I'm building the UI right now. Will eventually support graph, filtering and etc ..

Cool. What are you writing it in, Kosmic? I did a quick logger using Python and PyVISA when I last had the US Cal Club's voltage refs and temp sensor. Nothing fancy like yours.

[Kosmic]

When noise, and thermal emf is involve you need more than a spot check. Logging the same ref (or simply a short) for 2 days with and without isolation would probably be interesting.

...

But I will be recording some long term statistics from the 7061 as soon as I have that all done. Now if only I could get a GPIB adapter for my 7075...

If you have a VISA compatible gpib adapter I can send you my software. You configure via .xml file and it dump the data in .csv. I'm building the UI right now. Will eventually support graph, filtering and etc ..

Cool. What are you writing it in, Kosmic? I did a quick logger using Python and PyVISA when I last had the US Cal Club's voltage refs and temp sensor. Nothing fancy like yours.

All in C#. The plan is to move to .net core if I need linux support at some point. Decided to make my own since it was almost impossible finding a software supporting my instruments. So the driver to talk to a specific instrument is described in a .xml file. Pretty easy to create and edit. The code is generic and use the driver to send commands to a instrument. This way I can log almost anything and adding an instrument is fast and easy.

[bitseeker]

Sounds very cool. I look forward to seeing the upcoming plotting functionality.