Short wave adaptor. Came with 4 sets of coils for 15-100m (3MHz to 20MHz)
1930 Johns Catalogue
General Construction Notes for Wellmade Ltd:
Radios made for Johns in the 30's were often available in AC, DC or Battery. The inclusion of DC power options was because large tracts of Auckland (where Johns and Wellmade were situated) were supplied by DC power generation.