[Arran]

It's only logical that a 25 cycle set would have more filtering, instead of a 120 cycle ripple you would have a 50 cycle ripple. In Canada 25 cycle power grids were quite common, including in the area I reside now, with most manufacturers they had 60 cycle and 25 cycle versions, except for Rogers which seems to have used 25 cycle capable chassis in everything, unless the set had a clock or had motorized tuning. That was typically what they did, they either added larger, or extra filter caps, or added extra filter chokes, I guess Rogers dispensed with that to reduce parts inventories and worked via economies of scale since they knew that 25 cycle radios would work fine on 60 anyhow. There is one advantage to having a 25 cycle transformer, they have larger cores, and more iron, so they run cool even on 120 volts.
Regards
Arran