K71-7 precision capacitor

[shodan@micron]

void

[bsw_m]

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.

[bob91343]

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.

[bob91343]

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.

[bdunham7]

Whatever they use in these...

https://www.chinakaip.com/products/detail/ch-17t-precision-standard-capacitance-box.html

[bob91343]

Yes that is a precision capacitor.

[ramon]

Do they keep their properties after soldering?

[bsw_m]

I have finished testing the leakage current of the K71-7 470nF 250V capacitor at nominal voltage.
Voltage source: lab power supply B5-50
Current 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.

[Kleinstein]

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.

[dzseki]

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/#msg1880765

Some more measurements:
https://drive.google.com/drive/mobile/folders/1eVK5zdJ4sEdfRsW1ztHgo94Y7h8NaYLF?usp=drive_open

I've of course have kept a few for future use...

[Russ3000]

Used similar 0.49175 uF capacitors in a tube RIIA preamplifier with very good sound.

[Henrik_V]

Okay! lets fight!!!
Try show to me any other caps with 500nF capacitance and tolerance better 0.5%. 
Vishay say, 1...2% its precision capacitor, but i don't see better 1% caps.

A short look into my collection
Jahre makes them  .. or has made them

https://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

[Henrik_V]

here is the a bigger one