RCA Maritime HF Receiver question
 

I have acquired an RCA HF receiver that, among other uses, was included
with the radio installation on Liberty and Victory ships. The receiver
in question is the RCA 8506A, 110AC/DC set. I worked on one of these
that was installed in the RCA 4U equipment suite on the Liberty Ship
John Brown, in Baltimore and, at the time, was fortunately able to copy
all the books. However, unlike the 8506's in the 4U setup, this
particular receiver came with a heavy-duty, shielded case and a front
panel drilled for a typical Signal Corps (et al) nomenclature plate. The
plate is smaller that the commercial RCA plate as seen on the 4U
maritime equipment. I've been told that there is a Signal Corps
designation for this receiver, R-xxx, and it may have been used on Corps
of Engineers sea-going assets? If anyone any the info, I'd appreciate
it. This receiver is a bit on the rare side, it would appear.

de K3HVG