WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
I have tested a transformer as a choke and a toriod autoformer
as a choke in a choke input power supply. I Iloaded them to ~80% of there ac current rating with darn good results.
I think my results were about 5% different than calculated using
Duncan's power suply designer. Now this may not work in all cases but in the 2 cases I tried it sure did.