[Amps] What to buy? - ferrites and powdered iron

[Jim Brown]

On 2/4/2011 12:50 PM, John Lyles wrote:
> Fair Rite, Amidon don't offer
> any product for this use, but Philips/Ferroxcube and a few others do.

I plead ignorance to the use of any specific core materials for power 
amps, but I do know a bit about ferrites.  My comments as to the 
applicability of materials is based entirely upon their LOSS 
characterstics -- that is, Fair-Rite #61 and #67 have sufficiently low 
loss that they may be suitable for relatively high power in the MF and 
lower HF spectrum, and are widely used as transformers in antenna tuners 
and matching applications. Whether inductors wound on these materials 
are suitable in tube power amps is another issue, and since I don't 
design power amps, I haven't gone through the analysis to figure that out.

Let's make something clear -- Amidon does not MAKE anything, they are a 
retail distributor/reseller of materials made by others, like Fair-Rite, 
Phillips/Ferroxcube, and Micrometals. If you want to LEARN REAL FACTS 
about any of those materials, study the data sheets produced by those 
actual manufacturers, not the salesmen who change the part numbers to 
disguise the fact that they're selling at obscene 4X-5X markups. The 
Fair-Rite catalog gets a gold star for providing the most data, and in 
the most useful form, by far.  They also have a network of industrial 
distributors, listed on their website, who sell at FAR better prices.

73, Jim Brown K9YC