Public Broadcasting Financing Act - Establishes a Public Broadcasting Fund in the Treasury and authorizes to be appropriated to such Fund for each of the fiscal years 1976 through 1980 an amount equal to forty percent of the total amount of non-Federal financial support received by public broadcasting entities during the fiscal year second preceding each such fiscal year, up to specified limits. Provides for specified portions of the Public Broadcasting Fund to be distributed among the licensees and permittees of noncommercial educational broadcast stations.