OEP Screening Can?

Just a question for those that have used the OEP screening can.

On a PCB
mounted transformer why would you need to use the bottom piece of mu-metal,
not not just the can?

The reason I ask is that I left if off on my 1176 and
just put the can on top of the OEP sans the other piece of metal.

My main reason is that the holes didn't
line up with the pins very well and since it is conductive I was worried I
might short the trano if 2 or 3 pins touched that piece of metal, which was happening

Do I NEED to have it under the transformer, or can it be omitted like I did.

Thanks

Matt

You should use it for increased shielding since the PCB won´t give you magnetic shielding. But depending on the magnetic surrounding in your G1176 (toroidal main-trx?) and your studio (lots of wallwarts?) it might not be necessary.

Thanks Jensen,

From what I have read on Mnats site and here it really isn't a problem on
the 1176 on the output, and others have shared the same, my torrid is a way
away from the board.

I am going to use the screen on my FETboy's I'm building.

It seem that you don't get much of a problem when using it on line level
outs, after gain staging.

I guess it is more susceptible when using it as an input transformer, since
you have then got say 30 - 70db gain AFTER the trano, which would make me
think any HF present will be amplified?

Does that sound rational?

Cheers

Matt

If you don't use the bottom plate, the screening can won't be grounded (unless you solder-in a wire).

Best regards,

Mikkel C. Simonsen

Hi Mikkel,

How would it be grounded if you solder on the bottom plate?

Thanks

Matt

There's a ground pin on the transformer. That pin is also soldered to the bottom plate, grounding the can.

Best regards,

Mikkel C. Simonsen

FWIW / If still needed, there were one or a few more OEP-soldering threads.

Thanks,

Where did you read this? I'd like to know because my screen had no instructions, or is it just common knowledge to ground the ground pin to the screening can?

Thanks

Matt

[quote author="matta"]Where did you read this?[/quote]
I didn't read it (danes don't read instructions) - just a bit of logical thinking :grin:

Best regards,

Mikkel C. Simonsen

Thanks for the heads up Clint.

I couldn?t use the search yesterday so I posted. For anyone else you might
be interested here is a post I found on the can and soldering it:

http://www.groupdiy.com/index.php?topic=1778

And this one: http://www.groupdiy.com/index.php?topic=8656

I am still confused on an issue though. I assume ONLY the ground pin is
soldered to the base of the screening can, if you solder the other pins
surely this would short out the transformer?

Thanks

Matt

I am still confused on an issue though. I assume ONLY the ground pin is
soldered to the base of the screening can, if you solder the other pins
surely this would short out the transformer?

Click to expand...

Yes, that´s it. Soldering the can to ground gives you electric shield, the closed Mumetal can gives you magnetic shield
:sam:

[quote author="matta"]Thanks for the heads up Clint.

I couldn?t use the search yesterday so I posted. [/quote]

Hi Matt,

All fine, it was just posted in a friendly vein, so as a suggestion,
and not as a UTFSE (Use The F#*&ing Search Engine) kind of thing :thumb:

Bye,

Peter

Hah hah!

Yeah, I think I have been around long enough to know that. I may still be a DIY noobie, but not to the Forum.

I also cross referenced the other posts incase some ever needs to search for this again ;-)

Thanks

Matt

Somewhere there is also another thread about soldering the cans with my original comments. In a nutshell, I used plumbing flux and a torch to tin up the edge of the cans before the xformer was placed in it. I then allowed the cans to cool. The tinned cans were then easilly soldered with a 35W iron after the xformer was placed inside.

-Chris

I have had no problems soldering mine with my normal 50W soldering iron and normal solder. I may have upped the temperature a bit - can't remember.

Best regards,

Mikkel C. Simonsen

Wow, I need to get a bigger iron for doing jobs like this. Alas, I've only got a fixed 30 or 35 watter (I can't remember which). I bet CJ's big-bertha iron could weld the can shut without solder. :grin:

Before soldering these cans, I use a bit of sand paper or a needle file & sand off the outer coating of the metal where I want to solder until I can see some shiny metal underneath - just takes a few strokes. This makes soldering 10 x easier.

Peter