In US shipboard receivers, the RAL was the only HF receiver to use regenerative circuit.

Someone probably has a better memory and can recall the names or callsigns, but I remember at least one stalwart of the boatanchor list(s) from years ago who used the RAL as a primary CW receiver and said he'd put it up against any other.   I always admired that!  Anyone who has played with even a simple 1-tube regen knows how sensitive they can be, and with the RAL-type construction,  TRF front-end gain and selectivity, plus the audio filter I never doubted those claims.    Once you look inside an RAL it's hard to think of anything that could be done make it more rugged or stable, at least from a mechanical standpoint.

The RBB is a favorite of mine ever since one showed up in my driveway after a hamfest.   A local guy evidently figured that since he couldn't talk me into hauling it home, I'd at least adopt it if it turned up like a stray.    Something about cranking that tuning knob...

73, Bob W9RAN