The BTA-5F used three-phase power and a full-wave rectifier with 6-each 8008
mercury-vapor rectifier tubes. Don't remember the size of the filter
capacitors, but they weren't extraordinary as I recall. The filter choke was
about as big as a full-sized microwave oven. Full-wave rectified, three-phase
power isn't hard to filter.


Some RCA 5Ks and 10Ks were designed as two-phase, and, consequently, have four
rectumfier (sic) tubes.

This might be called a "four phase" rectifier in the same way as a three-phase,
full-wave rectifier is called a "six phase" rectifier.

Oh, these 5Ks and 5Ks actually run on three-phase feeders, as the primaries are
connected in a Scott-T, while the secondaries are connected as two-phase.

Buffalo and Philadelphia (including Camden, and undoubtedly RCA's plant as
well) were the last hold-outs of two-phase power in the U.S.