I'm reading through W2FMI's book on Baluns and Ununs, looking to replace
the 4:1 transformer used to feed my inverted-L (originally used with a
short, top-loaded vertical) with one for 1:1.78 (50:28.13) or 1:2.25 (50:22
ohms) ratio (BTW, there seems to be some disagreement about what the
impedance of a practical inverted-L is. Some sources show 28-ohms, some show
22-ohms).
Most of his Ununs are wound on 1.5-inch ferrite toroids with permeability
of 250. Problem is, Amidon doesn't sell such a core, the closest being
their "K" material with permeability 290 (which he specifies in some other
of his Ununs).
So, what to do? Should I use the Amidon "K" material in exchange for the
core specified? My use is strictly on 160M (I don't need it to have
bandwidth to cover 1-30 MHZ), and I want to have it "comfortably" rated for
2.5KW+ to provide some safety margin.
73,
Jeff Maass (jmaass@freenet.columbus.oh.us) Amateur Radio K8ND
USPSA/IPSC # L-1192 NROI/CRO NW of Columbus Ohio
25000 Members in 2000!
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