At 2:15 PM -0500 11/10/02, K4BEV@aol.com wrote:
>...Amidon - W2FMI 4:1 Balun....Does anyone on the list know what
>types of torids are used in these?
I counted the turns and measured my Amidon W2FMI 1:1 balun, then
matched it against Fair-Rite's spec sheets. Most likely your 4:1
balun uses two toroids of the same type as the one in my 1:1 balun.
IMO the ferrite is Type 61, which has a permeability ratio (mu/mu0)
equal to 125. It's a good, relatively low-loss material for HF
applications. Its Q peaks at over 300 at about 1 MHz, and has
dropped to about 100 at 10 MHz.
73 de Chuck W1HIS
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