The RBH was the Navy designation for the NC-156 receiver, a 10 tube superheterodyne that covered 300kc to 1200kc and 1700kc to 17mc in five bands utilizing National's famous moving coil-catacomb band switching system. The receiver also features single preselection, two IF amplifiers, crystal filter, S-meter, BFO and tone control. The dial uses the articulated pointer that indicates band in use by its alignment with the proper tuning scale on the illuminated dial.
National began supplying the U.S. Navy with their NC-100A direct dial readout, coil catacomb band switching receiver by 1939. Before WWII began, the Navy wanted minimal radiation from the receiver's Local Oscillator on the antenna. This was primarily to allow the receiver to be used in the presence of other shipboard radio equipment without interference. The first RBH receivers date from around 1940, however the receiver required some modifications for use at sea during WWII and a series of RBH receivers followed. All of the RBH series with number suffixes, e.g. RBH-1, RBH-2, etc., have an additional stage of preselection added with a bolt-in chassis and cabinet to house the additional catacomb section for the coils and an additional tuning condenser for tuning the stage.
Minimized RF radiation by a moveable coil catacomb, instead an intricate set of gears that simultaneously actuated two large ceramic band switches.
The RBH receiver was used as a general-purpose receiver working well to receive voice (AM) as well as Morse code (CW). It covered 300 KC - 1.2 MC, and 1.7 MC - 16 MC in five bands. It could be tuned with a calibrated dial. It was used on-board all types US Navy vessels during World War II, frequently located in the radio room or in the officer’s wardroom.