E.F. Johnson built a wide range of amateur radio transmitters (among other things), starting in the 1920s. They hit their stride with the postwar ham radio boom and continued through the early days of SSB. Every last one of the postwar rigs was a "Viking" something-or-other, which I suppose isn't a huge surprise for a company based in Waseca MN, up there where the descendants of Vikings farmed the land. The first two, delightful behemoths, were the Viking I and Viking II, but after that, there were Adventurers, Rangers, Navigators, Invaders(!) and the Challenger:
It's a CW/AM rig, the latter provided by screen-modulating a couple of TV sweep tubes (6DQ6) with a miniature beam tetrode audio tube (6AQ5). One does not expect high fidelity from this kind of arrangement but given a decent load, it should be adequate.
The knobs for bandswitch, "excitation" (grid drive) and mode switch are notably missing pointers to tell you where they're set. The originals were sort of subtle, white plastic pieces glued in at the bottom of the knobs, and I'll have to work out a replacement.
Does it work? The seller claimed it did -- it's got Johnson's poorly-documented "push to talk" modification (no schematic, just a step-by-step and partial pictorial) and a connections-unknown mic socket, so I'll want to trace all that out first, clean it up and then, perhaps, power it up via The Gadget.
What's The Gadget? That's a post for another time!