![]() ![]() These concerns are mainly associated with the very low values of core permeability and the subsequently low value of shunt impedance presented across the windings. ![]() I have serious concerns about the use of 4:1 voltage (Ruthroff) baluns on the output of atus, especially those constructed on iron powder cores (see separate notes. Some folks insist upon using a 4:1 voltage transformer on the output of the atu to provide a pseudo balanced feed, others say use a 1:1 current balun on the output, and yet more say put a 1:1 current balun on the input. Now Im aware of the arguments regarding where the common mode choke should be provided. This of course relies upon providing sufficient common mode choking impedance, even with a worst case output load imbalance. I had been using an auto-atu (CG-3000) with a string of ferrite chokes on the input side of the atu in order to float the whole unit above ground so that the output appears to be balanced. Ive recently been looking at the problem of providing a balanced feed from an un-balanced atu. ![]()
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