[turretslug]

It's a near-certainty that "SC" is a Signal Corps (i.e. US) designation- a query on one of the American vintage websites might be fruitful, I wouldn't be surprised of lots of these were made for field "morale" purposes and then dumped NOS on the market post-war.

In a sympathy-for-the-underdog sort of way, I quite like the loktal valve series- like the rimlock series, the presentation may have been misconceived, but the valves per se do a perfecrly good job for the most part. The main short-coming is short pins, leading to contact dependability problems. Quite a bit of the more "peripheral" US military kit seemed to use them- could it be that the earlier but tough and proven metal octal types were favoured for front-line kit and loktals, appearing in quantity for civilian use just pre-war, were used for less critical kit to ease possible production bottle-necks?

Maybe the original mains transformer was a 110V-only type, or just a commercial quality item that expired at some point.? I'd say this set ought to be a good performer, but the elephant in the room is the declining AM transmitter scene! Shame about the lack of LW, but hardly surprising in a US-originated set.

The B9a valve-socket on the LHS suggests something like a 7Y4-to-EZ80 adaptation?