I guess when you have as many Fisher tube units as I do, there is bound to be a few that get misplaced. This is an early 500-B I picked up some time ago and gave it a quick internal recap. I had also ordered a H.H. can capacitor kit for it, but this receiver was put to the side unfinished as other projects took over. I came across it the other day and decided I would replace all the cans, all 5 of them! By far the hardest re-can job I have ever done, and I have an 800-B waiting for the same treatment. All that's left is to power it up to see how it turned out, always a bit nerve racking after doing so much work, should be fine though if I use my DBT first. I thought since this is the early version with the tubes in front of the OPT's, it deserved some show off time, these are beautiful looking receivers and you don't see many early units. It's interesting how they created a heat shield that clamps to the phase inverter tubes, I wonder if that was added after production started.