NBDs from all around North America, LW BC stations and Navy VLF RTTY stations from around the world are easily received.Output is to a set of Western Electric 509W earphones as recommended in the manual.
The receiver and preselector panels are beautiful machine-textured aluminum with a matte-chromium finish.
The receiver case is copper-plated steel under the gray wrinkle finish and uses "shock-mount" feet that were screwed to the operating table, (the pre-selector and power supply were normally screwed directly to the operating table.) The Navy contract is dated December 2, 1941 - just five days before the attack on Pearl Harbor.
Tube line up is the same for both sets with four 6D6 tubes and two type 41 tubes (earlier versions of the RAK and RAL used earlier version tubes.) Both receivers use a dual dial readout (0/00 to 10/00) that must be correlated to a graph in the manual for tuned frequency.
Each receiver has its own separate power supply, the CRV[CND]-20131, which provides power through a ten foot long cable that connects to a terminal strip inside the receiver.
The power supply uses a 5Z3 rectifier, an 874 regulator tube and an optional 876 ballast tube that was supposed to be used when the AC line voltage was subject to fluctuations (supposedly that would cause instability in the RAL receiver at higher frequencies.) The AC supplied on ships is any but stable and fluctuations occur with just about any switched load on the line.
Meters on each receiver monitor the tube heater voltage (right) and the audio output (left.) The RAK receivers were intended for CW or MCW reception only as a low pass filter is permanently connected in the circuit to limit the upper audio response to about 1200 hz.
Use of [ND] in Navy designation indicates Andrea manufacture and [RV] indicates RCA-Victor.
(See our "Vintage Longwave Receivers" webpage for an in depth article about these receivers.) Considered by many military radio collectors to be the ultimate in WWII receiver design, the RBA, RBB and RBC receivers were "cost-no-object" in design and construction.
The RAZ-1 equipment shown are all assigned identical serial numbers - SN:65.
Performance of this operational RAZ-1 is incredible with an ability to extract weak signals out of the noise that is impressive.
The RAK and RAL were used in various shipboard applications (also submarine) up through WWII.