LF: Re: Re: Torroids

["mal hamilton" <g3kevmal@talktalk.net>]

On a recent trip to GI3/N Ireland I got several nice LOPT transformers complete with coils, ideal for the Dreamers band.

These transformers rewound for 137 and 500 work well and run COLD up to a few hundred watts.

There were millions of these around some years ago and found in old tube TV'S. The more recent ones in transistor TV'S are no good for Dreamers but the cores would probably be suitable with the old coils stripped off and rewound for 136 and 500 but they are not as sturdy as the old ones, maybe alright for qrp.

de mal/gekev

 

 

----- Original Message -----

From: GROUPS M0

To: rsgb_lf_group@blacksheep.org

Sent: Friday, July 16, 2010 11:03 AM

Subject: LF: Re: Torroids

Hi Chris,

 

The references 3C85 and 3C90 specify only the material grade but no the shape and size of the toroid.

 

We are more familiar with Amidon based references such as FT-50-43 that specifies a ferrite toroidal ring core, grade 43 and 0.5?x0.281?x0.181? in size.

 

 

The 3C90 grade comes from Ferroxcube; it is a Manganese-zinc (MnZn) ferrite for applications below 100 KHz appropriate for high-level drive transformers.

 

73s.

 

Juan, M0WWA

 

----- Original Message -----

From: Chris

To: RSGB LF Group

Sent: Thursday, July 15, 2010 4:47 PM

Subject: LF: Torroids

Hi again Juan,

Sadly after an exchange of e-mails, that website you gave me cannot supply the correct type of torroids. They say I need type 78 (for 3C85 or 3C90 equivalent) and they don't do them.

I wish they'd all stick to the same format for identification of the various types.

Thanks for trying!

Chris, G4AYT.