I come up empty on this one in the ads, but my gut feeling is that it is an unengraved version of the Broadcaster (21J). The only Broadcasters we have ID'ed are engraved with a full numbered dial. The subject watch dial differs, but that could be the dial matched to unengraved Broadcasters. We see that distinction in other models from this time period.
Case with swivel lugs is pretty distinct and appears to be pretty unique.
I think we see the same situation with this one and this one - another swivel lug model produced at the same time. These appear to be a Kenneth but are engraved with a full number dial and identical band, while ads show unengraved with an alternating number/stick dial and different band. Two in the database as unknown. Subject watch seems to verify that Engraved swivel lugs equals full numbered dial and unengraved equals alternating dial. Both Broadcaster and Kenneth only appear for a couple years and are gone. Scant advertising of one variant of two before production and marketing ceased? In each case, the "fancier" model had a better case design, dial and band?
Just my thoughts.
Broadcaster