From the schematic on Nostalgia Air, this radio looks very similar if not identical to the 41-81. I just finished restoring one electrically, and I made a battery for it based on two "D" cells in parallel for the A supply and seven nine volt batteries in series for the B supply.
In this thread,
http://philcoradio.com/phorum/showthread.php?tid=1778 a forum member nicknamed "Batterymaker" included pictures of how he did it. A very neat job. Mine is similar, only slightly cruder, since I used seven 9 volt battery connectors from Radio Shack instead of making a nice connector board like he did, and I used the connector and cardboard box from an original battery that came with my radio. I don't know how to make my own as he does. I used two D cells instead of C cells as Batterymaker did. I'm not sure how much difference it would make, but I figured the D cells would last longer, and they fit just fine.
The box (mine is 1/4 inch plywood) containing the modern batteries slides into the cardboard box and looks completely authentic.
I'm pretty sure Batterymaker builds and sells these very authentic-looking batteries to order. If you contact him via PM he might be able to sell you one.
Of course, you wouldn't need to get fancy. You could just tape the modern batteries together and put them in the battery compartment. You could solder the connections to the connector on the radio and insulate with shrink wrap if you couldn't figure out how to make a female connector. With the back on, no one would know what it looks like.
You could make an AC adapter from any of several designs that are available on line. One such design, for the B supply only, is at this site:
http://www.antiqueradio.org/bsupply.htm . You'd have to use 1-1/2 volt batteries for the A supply unless you can find plans for an A/B adapter. You'd also need to put a hole in the cabinet somewhere to bring out the AC cord. There may be antenna holes on the lower right side of the cabinet that you could use or adapt for this purpose.
There is also a bench style AC adapter for A, B, and C supplies available as a kit from Antique Electronic Supply if you just want to operate the DC radio on the bench. It looks crude, but you could put it in a kit box. Maybe you could even shrink it from the assembled kit shown, but I doubt if you could make it fit in the battery compartment of the radio. (But maybe you could with careful layout on perf board or something.) Here is the AES web site.
http://www.tubesandmore.com/ Click on "Kits" and then on "Power Supplies". You'd still need to figure out how to make a connector.
Do replace all of the paper capacitors, the electrolytic capacitor, out of spec resistors, and crumbling rubber-insulated wire before putting power to your radio. In my radio, much of the rubber insulation was soft and very supple, so I just left most of it. On a few of the wires the insulation was hard, cracking or crumbling, so I replaced or sleeved all of those.
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