You may want to rethink the Astron 50M. I have had one for 20+ years and it has been a solid trouble free power supply. Except for one issue....it has an annoying acoustic hum when it is on. It is loud enough to be irritating in a quiet room but you can't hear it above the din of radio noise in a shack.
It seems to be a common problem with the analog Astrons, sometimes a chunk of rubber or even wood between the case and transformer top will stop it.