Ideas for shielding can? (inductor)

[JW]

Anybody off the top of their head have any ideas for an RF shielding can, from I don't know, the grocery store or something. Some product I'm not thinking of, whose container that would make a good shield from the nearby torroid.

??

 

[zebra50]

Take a magnet with you, and see if any suitably sized tins of beans* stick to it. That would be a good start!

* It doesn't have to be beans. I remember bodging a holed car exhaust for a neighbour. I asked her if she had an empty cat food tin so that I could use it to patch the hole. She went inside and came back again after five minutes and said "I haven't got a cat. Will tomatoes work?" 

 

[0dbfs]

Well even though it took her five minutes to figure out she didn't have a cat we'll give her credit.

Did the tomatoes work or did you have to run out for cat food?

-jb

EDIT:
Canned spinach is high in iron...

 

[JW]

Thanks
Those cans are pretty big though compared to what I want. The inductor is only about 2"x2"x2"

 

[gemini86]

There may be a pipe or conduit end cap that could work you. Copper will be easy to find, but that's only good fir rf shielding, right?

 

[mitsos]

how are you having RF interference from your toroid?

 

[gemini86]

I think OP is mixing EM and RF...

 

[mitsos]

I know, I was just being a smart ass.

sorry... 

Have you tried shielding the toroid? Normal steel will not work, much less tin cans.  You need to put some silicon steel strips around the toroid (same stuff the toroid core is made of). One long strip a few times around will work nicely, but you'll first want to rotate the toroid while listening to the hum to find the position of lowest interference. The guy selling pultec parts in europe had some strips a while back, don audio I think is the site. Maybe he still sells them.  Or call trafo vendors around you, they might have something.  On the other hand, it's the same stuff the toroid core is made of, so if you have a bad toroid you could try taking it apart, but you might find it's epoxied in which case that'll be a waste of time.  Too bad everything is made in china nowadays, otherwise you could call a local toroid winder and get some of this stuff for free...

 

[Stagefright13]

I bought a sheet of MU metal here for cheap. Used it on a few projects. Cuts like butter with tin snips. And solders great with regular solder. (To make A can) http://www.lessemf.com/magnetic_shielding.html

Bad pic but made A nice tuna can with it in a few minutes......

John

 

[JW]

Good tips!
Thanks guys.

Yeah, I meant EM, not RF, sorry. Spaced out there.

StageFright, what is that you grounded it to, just a piece of metal connected to the chassis? Just curious.

 

[bruce0]

rotate the toroid

I second mitsos on this, rotating the toroid can make a huge difference.. On power toroids the interference is far from symmetrical or smooth.  Listen for, or measure, hum in the 60,120, 240 frequency range (EU 50,100,200)  and rotate the toroid to minimize it.  If there is only one channel you will surely make a big difference, if there are multiple channels, you will be doing some "dividing the baby" but can still find a spot that is better overall.

 

[Jean Clochet]

There are two or three units that got used for years in a broadcasting setup that contained power transformers that I had shielded with an empty tin of salmon.  I guess a "tuna fish can" would be the way to go in the US!

Other than spending an hour getting rid of the smell first, it worked in that situation.

Sounds like you're shielding the inductor rather than the power traffo but, with toriods, you need to make sure the shielding can doesn't create a shorted turn or you'll not be happy!