[GarySP]

The 80 and 5Z3 are both full-wave rectifiers, and interchangable. The difference is the current draw and output. The 5Z3 is the 80 on steroids, but at a price. The 80 draws 2.0 amps to the heater, and the 5Z3 draws 3.0 amps. Considering that the transformer is already dealing with the higher line voltages today from when built do you really want to push the issue by using a 5Z3? If the schematics say 80, I, like Vinser above, would use the 80. Take care and BE HEALTHY! Gary