NK4-1 low current and high resistance calibrator (made in Belarus) - Page 1
Forum section: electronics / general

author: bsw_m
author_rank: Frequent Contributor
timestamp: August 11, 2020, 10:55:57 am
content: NK4-1 has arrived.This reference calibrator designed in MNIPI and go to production in 1989 year. Later this instrument has certified as low current & high resistance standard.My unit produced at end 1996year and have serial number 14.Minimal metrologically significant current that this calibrator can generate is 1E-17A with resolution up to 1Е-20AFirst power on attempt fail. Computer in this device has not work. But after cleaning sockets, computer started.Photo and first test.

author: TimFox
author_rank: Super Contributor
timestamp: August 11, 2020, 03:46:29 pm
content: Very nice device, with that interesting proprietary low-leakage connector. Is there a standard cable to connect with the Keysight B9285A triax input?(For my less-sensitive requirements, I rely on a Keithley K261 "picoampere current source" to work with my Keithley 610C analog and 616 digital electrometers. It is merely a Kelvin-Varley divider driving a set of the usual glass-encased Victoreen carbon resistors mounted on a rotary switch. The most sensitive range is 0 to 9.99 V through a 1 x 1012ohm resistor.)

author: bsw_m
author_rank: Frequent Contributor
timestamp: August 14, 2020, 10:06:48 am
content: Quote from: TimFox on August 11, 2020, 03:46:29 pmThanks!This device doesn't have standard cable for connect to B2985A and similar. Need to DIY.For currents >=1E-9A this device use network of precision microwire resistors and DAC.For currents <1E-9A this device use capacitors and DAC that generate ramp voltage.The use of differentiating capacitors to generate ultra-low currents in this calibrator has solved 2 problems at once.1. Lack of stable ultra-high resistance resistors suitable for the high precise generation of such currents.2. Get rid the thermal noise of the resistors.The amplifier of V7-45 for the same reasons also using integrating capacitor in their feedback. - Full eliminate current noise from resistors. And more precise measurement, due the capacitor is more stable than ultra high resistance resistors (time and temperature).Photos: output connector with sapphire insulator on differentiator №2. This differentiator used to generate output currents from 1E-14A to 1E-16A. And connector with amber insulator on one of kit's cable.

author: bsw_m
author_rank: Frequent Contributor
timestamp: August 14, 2020, 10:34:50 am
content: Sweet couple: NK4-1 and V7-45. Calibrator that can generate 1E-17A and electrometr that can measure this current.On photo there devices are not acting.

author: bsw_m
author_rank: Frequent Contributor
timestamp: August 22, 2020, 12:46:45 pm
content: Teardown base block of this calibrator:https://drive.google.com/drive/folders/1WmNponhWYFL2ooBO2Bm_bLCmdCyd0okh?usp=sharing

author: bsw_m
author_rank: Frequent Contributor
timestamp: October 14, 2020, 03:05:34 pm
content: For those who can read in Russian. An article on the creation of a standard for ultra-low currents

author: bsw_m
author_rank: Frequent Contributor
timestamp: October 16, 2020, 06:04:14 am
content: I scanned the first book of documentation for the NK4-1 device. Perhaps someone will come in handy.https://drive.google.com/drive/folders/1D9E9QGc1qtWnUpHSRtgMRAiQxbgFVZO7?usp=sharing