Soviet capacitor questions. - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: August 06, 2022, 02:05:17 am
content: I read that for capacitors like the K40 series the K40 designates the dielectric, but what about the K72 for example? it's a teflon cap but all the other K series caps are PIO.MBM caps, I've read that they're "aluminum foil wax paper PIO caps with the same dielectric as the K42Y-2"... wax + oil?? what are they then?and the K42 dielectric corresponds with other caps in that series which are said to use a metalized dielectric.and the metalized polypropylene dielectric, why is this a thing?metal seems to be a bad choice for a dielectric, can someone shed some light on why this was done and what are the benefits?and there's many other caps which I haven't seen any info online, like the:and the VMT-2 caps, I took one apart and it seems to be regular paper in oil, but not sealed, all the ones that I have leak pretty bad (electrically)and some of the KSO-5 caps (they just look the same, don't have any designation on them), were actually paper.

author: AnalogueLove1867
author_rank: Regular Contributor
timestamp: August 06, 2022, 08:58:45 am
content: A few pointers.1) A metalized dielectric is 100% referring to a metalized film.https://en.wikipedia.org/wiki/Metallised_filmSo It actually refers to the method used to coat the dielectric with a conductor (vapor deposition in a vacuum).2) Very old capacitors were frequently metal foil spaced with oil impregnated paper. The capacitor roll is then sealedwith solid wax just underneath the metal or cardboard capacitor casing. Very rarely the opposite arrangement ofa wax paper dielectric sealed with oil was used.3) There are so many components named K72 and K42 That the identity is a guess.Is it distantly related to this?https://www.ebay.com/itm/351310115935

author: AnalogueLove1867
author_rank: Regular Contributor
timestamp: August 06, 2022, 01:47:00 pm
content: Ok, cheers wish you the best.Will help if I can.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 06, 2022, 05:59:58 pm
content: Paper with oil capacitors can have very high dielectric absorbtion. This may looks a lot like leakage and makes it difficult to measure the true leakage.

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 07, 2022, 03:40:31 pm
content: Quote from: ELS122 on August 06, 2022, 02:05:17 amProbably, you may use google-translate here:Capacitors. Look at table 10.K40, K41 and K42 are paper types. K70, 71, 72, ... K77 - film types.

author: quadtech
author_rank: Regular Contributor
timestamp: August 07, 2022, 03:49:53 pm
content: The late Ed Brown compiled this list over on diytube several years agohttp://www.diytube.com/phpBB2/viewtopic.php?t=898

author: Gyro
author_rank: Super Contributor
timestamp: August 07, 2022, 06:53:34 pm
content: K40s sound very good in filter applications - specifically speaker crossovers.

author: Gyro
author_rank: Super Contributor
timestamp: August 07, 2022, 09:07:25 pm
content: Quote from: ELS122 on August 07, 2022, 08:46:49 pmI wouldn't even consider any of the non-hermetic PIOs (and maybe some of the others), after all, these are NOS Soviet. A non-hermetic PIO is as close as you can get to a Rifa!

author: Gyro
author_rank: Super Contributor
timestamp: August 07, 2022, 09:22:39 pm
content: P.S. The attached databook may help (it has both Russian an English text)...

author: strawberry
author_rank: Super Contributor
timestamp: August 07, 2022, 10:44:21 pm
content: 70's NOS MBM? one with rubber seals tested above 500k leakglass sealed is environment stableFKP-4 in Gohm range