[Amps] input/output transformer switching

[Jim Brown]

On Thu, 13 Dec 2007 17:21:30 +0000, kg7hf at comcast.net wrote:

>I'm currently using the semi-rigid coax transformers with the 
type
>61 core material.   According to the app note, using type 43 
>material would pretty much get me to where I need to be,

I've missed the original question in this thread, BUT, perhaps I 
can cast some light on the topic. 

#61 material is a LOW LOSS material at HF, and IS suitable for use 
in transformers. So is #67.  #43 is a HIGH loss material at VHF, 
and is generally NOT suitable for transformers that must handle 
power. It may be fine for small signal transformers, and it is a 
very good material for RFI suppression (chokes). 

There's a lot of material in my RFI tutorial that lays the 
conceptual basis for this discussion, and lists other references.  

http://audiosystemsgroup.com/RFI-Ham.pdf

These materials are made by Fair-Rite, a very good US company 
based in upstate NY. Their website lists distributors and has an 
EXCELLENT pdf catalog. The vast majority of ferrite materials sold 
in the ham market are actually made by Fair-Rite, and are sold at 
obscene mark-ups by vendors like Amidon and Palomar. 

73,

Jim Brown K9YC