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The RZB receiver is a small self-contained receiver with an external
battery pack in a similar housing, that could be carried on the chest
in a canvas case with two pockets. It was built in the USA around 1943
and was used for the reception of instructions and BBC broadcasts.
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It was originally developed the the US Navy and was probably intended
for the reception of instructions during beach landings. As such,
both the receiver and the battery case are water tight and all
accessories are carried out in rubber.
The initial models had a frequency range of 2 - 5.8 MHz, but the unit
was later modified for an extended frequency range of 5 - 13 MHz AM.
The extended units were dropped over occupied European territory
during WWII and were subsequently used by resistance groups.
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As such it resembles the British war-time MCR-1,
the Sweetheart
and the post war Mk-301 receivers.
The RZB receiver was manufactured by the Emerson Radio and
Phonograph Corporation in New York (USA) around 1943.
The headset is connected to the battery case with a fixed rubber lead
and consists of two flat speakers in a canvas skull cap, so that it
could be worn under a standard helmet.
Unfortunately, the skull cap is missing from the item shown here.
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The receiver is beautifully built and operates around 5 valves:
RF pre-amplifier (1T4),
local oscillator/mixer (1R5), IF amplifier (1T4), detector (1S5)
and the AF amplifier (1L4). For frequency adjustment it uses
coil tuning (permeability tuning). The sensitivity of the receiver
is 1 to 4 µV at 1mW audio output (into 600 ohm headphones).
The unit is powered by two voltages: 1.5V/250mA (LT) and
67.5V/4mA (HT). The rightmost picture below, shows the original
batteries inside the battery compartment.
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In Naval use, the soldier's metal helmet would be used as the antenna.
A short piece of fixed wire (approx. 70 cm) and a screw-on terminal
is used to connect the receiver to the helmet.
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Below is the circuit diagram of the RBZ receiver
[1]
taken from page 55
of the instruction booklet. Click the image to download the entire page
in full resolution. Please note that the valves are drawn sideways, with
the cathode on the left and the anode on the right.
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© Copyright 2009-2011, Paul Reuvers & Marc Simons. Last changed: Tue,12 Apr 2011.22:37:58
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