The Astron power supplies use a reference supply for the main regulator circuit.  If the filter cap fails on the reference supply it will have a large amount of hum on the reference voltage which will be duplicated on the output of the main regulator.

Stuart

"Make each leg about 32 feet and 10 inches long if you want 14.250 to be the approximate center frequency."

That would be the overall length for 20 meters. What you need is about 16 feet 5 inches per leg.  32 feet and 10 inches per leg would be darn close to what is needed for a 40 meter dipole.  

Be sure to cut the wire about 12 to 18 inches longer than the design length, that way you can fold back the excess length until resonance is reached.  It's a lot easier to remove wire than add it.

Stuart  
WB6RXG