V7E-42 - 16 channels electrometry source-meter

[shodan@micron]

void

[MegaVolt]

Should we wait for a teardown?

[chekhov]

Price per unit into old-stock store radiopribor@bk.ru: 850 USD. (seller is very hard to communicate and slow, but my unit arrived with good condition, see above)

Sadly this seller does not have В7-45 anymore ...

Btw, these triaxials on switch module also sapphire-based ?

[chekhov]

This switch does not seem to be a part of ZIP for this instrument, doesn't it ? If so, does it have it's own name ?

[bsw_m]

V7E-42 "КОП" interface(GPIB IEEE-488.1) checked - fully operational with Keysight 82357B clone + Raspberry Pi. 

Wonderful!
This confirms my assumption that it will work well. Since I keep track of the continuity of solutions in this device and the earlier microprocessor-based DMM V7-39.
Moreover, continuity not only in the digital part, but also in the analog part (ADC, scaling amplifier).

[khach]

Any information about electrometric MOSFET pair in HT002 hydride? What crystals used in it?

[eliocor]

SMD-cap in eighties... hm... i'm really surprised.

Just for curiosity, is there any way to get an higher resolution picture of the hybrid?

.       TIA
_         Elio.

[bsw_m]

NT002(NT003) Electrometric mosfet pair designed (R&D) by Dvornikov Oleg Vladimirovich. (MNIPI) https://orcid.org/0000-0002-6632-429X
NT002 mosfet pair also used in electrometric amplifier U5-11

[Kleinstein]

It looks like there is quantization visible, like 0.1 fA steps.

[Kleinstein]

The last end (e.g. factor 3-10 in the time scale) of the Allan variance curve is usually rather uncertain, as there is naturally not enough time to do much averaging over such long time spacings. If the measurement is repeated one could get quite different values there.
Still the stability looks quite good though not much different from the one before.

Having the maximum at some 15 seconds is odd. What is happening at this time scale ? Is there something like a beat frequency with mains hum, or is here some kind of digital filtering going on for the shorter times ? The zero / reset cycle is considerably longer, more like 1000 seconds.

[chuckb]

Thanks for all the pictures and details about these wonderful instruments!

I have used Stable32 with 500k sample data sets without a problem. It just takes 10-20 sec to compute the AD. One time I tried to process a 1,000,000 sample file. The software crashed.  This was with a workstation PC.
Good luck!

[Kleinstein]

I don't think one would really need a TCXO : there would not be sub ppm stability anyway.
The low pass filter may mave to be lower cross over, so that there is more averating over the steps from the DAC. 1/10 second would be only some 100 LSB steps (for 20 min cycle).  I doubt one would need a faster reaction so the filter would likely be better more at some 1 Hz  - still a parameter to trim for the final version.

The gain stage from 2.5 V to 20 V would not need to be super stable - just avoid extra crurrent noise from the resistos. One may still consider a different reference, possibly with lower noise, though higher long time drift. This may be as crazy as a 18 V battery stack. One point one does not want is something like popcorn noise.

With a giid timing resolution from the µC one may not really need the DDS generator for the clock. Some of the STM32 µCs offer PWM with very fine time resolution (sub ns range), that could be used instead.