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For
medium wave reception.
Wooden casing, painted black. The sides are covered with
black book muslin. This muslin also covers the frame
antenna wrapped around the sides. The top and the knobs
of the radio are made of bakelite. The radio can be opened by turning the screw in
the middle of the front panel. The price was 210 Kč in 1935.
The
circuit of the Weekend is based on an invention by E.H.
Armstrong from 1922: the super-regenerative
receiver. This principle can be used to make a
sensitive receiver with a minimal amount of
components. A detector with feedback (in this case a
A441N, set-up as Negadyne) oscillates in a normal way,
but this oscillation is periodically interrupted by
a much lower frequency,
the quench frequency. This frequency must be just
above the audible frequency. As a result, impulse modulation in
the anode circuit of the valve is created, in the
rhythm of the modulation of the transmitter
received.
Advantages are high
sensibility and a simple circuit. Disadvantage is
the whimsicality of the circuit, specially in low
frequencies like medium and long wave.
The extra coil with
the 1500 cm capacitor (see circuit) were added to
make the circuit oscillate in the quench frequency. (With
many thanks to John Hupse)
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