[Milsurplus] Berry 148A power supply ?

[Hubert Miller]

I found in my treasure chest a nice little blue carry box with hinged lid, closure latches, and carry handle:
Berry Electronics 148A. Says 48 volt supply. I hoped it was not a switcher, so I was pleased to see when
I opened it, a nice sized power transformer and no filter capacitor over 100 volts. The output however
is around 55 - 60 volts. I see it uses an LM723 regulator chip. plus some other  semis. The reason I am 
pleased to see it's a linear supply is that I thought it would be nice to use with small vac-tube receivers.
This was scrounged from excess telephony industry stock. I was unable to find anything on it on the 
'net, so I suppose if I want to see the schematic, I'll have to draw it myself. 
But - anyone know what this was used for? I don't see that It could supply more safely than 100 -
200 mA. 
thanks-
Hue