K71-7 precision capacitor - Page 1
Forum section: electronics / general

author: shodan@micron
author_rank: Contributor
timestamp: June 11, 2021, 08:58:29 pm
content: void

author: bsw_m
author_rank: Frequent Contributor
timestamp: June 11, 2021, 11:18:14 pm
content: In fact, these capacitors actually have very good accuracy and low Df and Da.I am sorry, I could not find my data on the measurement of dielectric absorption (it was a long time ago). But I remember exactly that the dielectric absorption of these capacitors was low. Measuring again is a lengthy process and requires preparation. But I measured the capacitance and Df. I measured 2 randomly taken samples with a nominal value of 470nF 5% tolerance and 100nF 0.5% tolerance. Measurement frequency was 1000Hz.

author: bob91343
author_rank: Super Contributor
timestamp: June 12, 2021, 02:19:27 am
content: I don't consider 0.5% tolerance high precision. But it's a relative term. I think these could be considered general purpose, although they are better than most.

author: bob91343
author_rank: Super Contributor
timestamp: June 12, 2021, 03:00:11 am
content: You can't fight over opinions. Since precision is a general term, each of us interprets it differently. I think 0.1% is precision. Those would be expensive lab standards but I think that gets into the realm of precision.

author: bdunham7
author_rank: Super Contributor
timestamp: June 12, 2021, 03:16:57 am
content: Whatever they use in these...https://www.chinakaip.com/products/detail/ch-17t-precision-standard-capacitance-box.html

author: bob91343
author_rank: Super Contributor
timestamp: June 12, 2021, 03:56:15 am
content: Yes that is a precision capacitor.

author: ramon
author_rank: Regular Contributor
timestamp: June 12, 2021, 04:05:44 am
content: Do they keep their properties after soldering?

author: bsw_m
author_rank: Frequent Contributor
timestamp: June 13, 2021, 08:06:58 am
content: I have finished testing the leakage current of the K71-7 470nF 250V capacitor at nominal voltage.Voltage source: lab power supply B5-50Current metter:V7-49 electrometer.Series resistor ~ 10GΩ KVM.Test time ~ 9.5 h.Leakage current is about 8pA.Possibly, the leak current can be even lower, but 10GOm resistor too small in order to get rid of the noise rise in the lower measuring range.I am attaching a raw data file.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 13, 2021, 02:22:26 pm
content: When testing the leakage current directly, there is not just the noise of the ampmeter, but also noise if the voltage source to power the capacitor. Chances are the 250 V source is more noisy than the electrometer input votlage.The other part that is seen is the dielectric absorbtion of the capacitor - that is likely much of the initial decay part.

author: dzseki
author_rank: Frequent Contributor
timestamp: June 13, 2021, 09:08:10 pm
content: I don't have these for sale anymore but you might find it interesting afterall:https://www.eevblog.com/forum/buysellwanted/wts-precision-capacitors-109nf-125v-0-25/msg1880765/#msg1880765Some more measurements:https://drive.google.com/drive/mobile/folders/1eVK5zdJ4sEdfRsW1ztHgo94Y7h8NaYLF?usp=drive_openI've of course have kept a few for future use...

author: Russ3000
author_rank: Regular Contributor
timestamp: June 13, 2021, 10:23:59 pm
content: Used similar 0.49175 uF capacitors in a tube RIIA preamplifier with very good sound.

author: Henrik_V
author_rank: Regular Contributor
timestamp: June 18, 2021, 07:30:18 am
content: Quote from: shodan@micron on June 12, 2021, 02:22:47 amA short look into my collectionJahre makes them .. or has made themhttps://www.jahre.de/en/products/mica-capacitors/small-capacitors/actual offer is 0.5% , but that's just a question of $$ if you ask them

author: Henrik_V
author_rank: Regular Contributor
timestamp: June 18, 2021, 08:38:04 am
content: here is the a bigger one