pc smps torroids - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: December 06, 2023, 02:28:40 pm
content: can the torroids from scrap smps units be used as common mode chokes at hf?.

author: madires
author_rank: Super Contributor
timestamp: December 06, 2023, 02:58:30 pm
content: The common mode chokes in SMPSs are meant to filter frequencies up to the lower radio frequency bands. Which frequency bands do you mean? And how much RF power?

author: Andy Chee
author_rank: Super Contributor
timestamp: December 06, 2023, 03:06:50 pm
content: If you're talking about the SMPS toroids that I'm thinking of (typically yellow enamel coating), then no, those toroids will not work. That's because they are made of powdered iron which is the incorrect material. You need ferrite material for a common mode HF choke.If you want to salvage ferrite, look no further than scrap VGA monitor cables.Incidentally, you can use your VNA to measure an unknown toroid's parameters. Then you can compare the graphs to a known #31 or #43 or #76 ferrite datasheet.https://owenduffy.net/blog/?p=5198

author: p.larner
author_rank: Frequent Contributor
timestamp: December 06, 2023, 03:26:11 pm
content: i was thinking of 10w max from 80-10m

author: madires
author_rank: Super Contributor
timestamp: December 06, 2023, 03:37:45 pm
content: Look for ferrite material 73.

author: p.larner
author_rank: Frequent Contributor
timestamp: December 06, 2023, 03:43:56 pm
content: i am not worried enough to hunt for them as have no rf issues feedback etc,its just i have a bunch of dead smps units and wondered if the torroids were of use for ham radio.

author: madires
author_rank: Super Contributor
timestamp: December 06, 2023, 03:56:05 pm
content: Quote from: Andy Chee on December 06, 2023, 03:06:50 pmThe yellow ones (with a white side) are material 26, good for up to about 1MHz. Because of the iron powder (distributed air gap) they are great for DC/DC converters.

author: A.Z.
author_rank: Super Contributor
timestamp: December 06, 2023, 05:58:53 pm
content: Quote from: p.larner on December 06, 2023, 03:43:56 pmhow can you say you have "no RF issues"; did you take some MEASUREMENTS ?https://owenduffy.net/blog/?p=458https://owenduffy.net/module/icm/index.htmIf not, then what are you talking about ?As for those iron powder toroids, yes, you can use them for an ATU, and a pretty good one toohttps://pa0fri.home.xs4all.nl/ATU/FRImatch/FRImatcheng.htmbut for sure, not for baluns/chokes, the material doesn't fit the requirements, you'll need NiZn or the like, plug in the brain and gather some infoshttp://www.karinya.net/g3txq/chokes/https://gm3sek.files.wordpress.com/2019/01/G3TXQ-RC.pdfand, this time, try to UNDERSTAND thingsP.S. the spelling is "toroids" not "torRoids"

author: coppercone2
author_rank: Super Contributor
timestamp: December 06, 2023, 09:34:59 pm
content: yes,if you crack the code then millions of pounds of junk boxes will suddenly gain some valuewe have been waiting at least 30 years for this moment. Otherwise i predict they will be inert until the discovery of the alternate topology subspace repeater made by people some where around 3000 years from now.maybe its possible to strip the coating and crystalize some kind of material in there under the correct conditions to utilize them. With high pressure fed electroplasmic deposition reactors. Only possible for cores aged at STP for at least 25 years.