[GreenKeys] PS/loop supply question

[Kevin H. Phillips]

Question:  Is 200vdc too much to use for a loop supply?

I acquired  Lambda Electronics Model 28 regulated power supply from a 
local ham.  Lettering on the case indicates it can be regulated from 
200-325v at 0-100mA.  I have not yet tried to fire it up,  it needs at 
least two tubes replaced, but I was wondering if this could be used for 
a loop supply.

Also, does anyone happen to have schematics for this unit or know where 
I might find any?

Thanks,
Kevin