[Arran]

That was probably the smart move, in my opinion, I've seen a few attempts where someone tried to convert a battery operated tube set into an AC set, with AC tubes, and they never seemed to produce a functional set afterward, they seem to get just so far, and then loose the handle. On the other hand I have seen a number of sets where someone retained the original battery tubes, and circuits, and constructed either an outboard power supply/battery eliminator to operate it from the AC power line, or built an inboard power supply in an empty area of the chassis, and almost all of those were successful. The nice thing about battery sets is that whilst the voltages and currents required are different from lets say a transistor radio, you can throw together a very good power supply using inexpensive off the shelf or salvaged parts.
Regards
Arran