I've use a 300a for my AM station. I'm the second owner. I have a acquaintance with 300a RF deck only. He unfortunately misplaced the power supply during a move many years ago. The amp for trade is the white Chrome Top Model just as mine is. Nomad did answer a post and explained that it would be devastating to use another power supply on a 300a if the power supply wasn't the compatible. There were a few differences between the Palomar 300 a RF decks (I think) I don't think it's the power...
PALOMAR 300A AND POWER SUPPLY SWAP
PALOMAR 300A AND POWER SUPPLY SWAP