[600MRG] Ferrite cores

[jrusgrove at comcast.net]

Rudy

<2 cents>

When working on the Class-D kW decks I found 78 material the best choice on 137 kHz and 79 the best 
for 500 kHz ... although 78 was an acceptable substitute and is readily available.

http://www.w1vd.com/137-500-KWTX.htm

</2 cents>

Jay W1VD  WD2XNS  WE2XGR/2  WG2XGR/2


----- Original Message ----- 
From: "Rudy Severns" <n6lf at epud.net>
To: "600MRG" <600mrg at w7ekb.com>
Sent: Monday, February 24, 2014 2:41 PM
Subject: [600MRG] Ferrite cores


> Following up on my earlier comments on ferrite cores for 600m.  I went to
> the www.mouser.com web page and checked out the availability of cores.  I
> also went back through the Fair-Rite catalog reading the material
> descriptions to jog this old memory.
>
> A few comments:
>
> 1) The type 31 material is MnZn but it's primarily for EMI suppression.
> The range of core sizes is limited and I wouldn't recommend it for transformers and
> inductors anyway.
>
> 2) I looked over the Fair-Rite MnZn materials and it appears to me that the
> 77 material is really the most appropriate for 600m.  Fortunately Mouser (and
> I'm sure other suppliers) has a great selection of toroids in stock.  One is 4" in
> diameter by an 1" thick!  Of course those are $40 a pop.  The smaller ones
> are much cheaper.
>
> 3) Fair-Rite also has EE, EI, EER, etc cores in 78 material as well as some new material, 95 and 
> 98, which I haven't had a chance to evaluate.
>
> 4) For an inductor with a ferrite core you will need to use an air gap.  The EE, EI, UU, etc cores 
> make this easy and Fair-Rite has applications information on AL and gap lengths.
>
> 5) The ARRL used to sell a very nice book by Doug DeMaw "Ferromagnetic-Core Design & Application 
> Handbook".  I don't think it's for sale anymore but if you can get your hands a copy grab it!  If 
> I put together a monograph for 600m magnetics I would shamelessly plagiarize DeMaw!
>
> 6) Besides Fair-Rite, TDK also has a large line of ferrite cores although I haven't looked at the 
> material characteristics for years so no recommendations.  Mouser sells some TDK cores.
>
> What this discussion has done is to prompt me dredge up things I haven't thought about for years 
> which is kind of fun.  I'll have to give some thought to some guidelines at least.
>
> GL and 73, Rudy
>
>
> _______________________________________________
> 600MRG mailing list
> 600MRG at w7ekb.com
> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com