The R 400 is a single and double sideband radiotelephone
receiver for telephony communication in the 1.6-4 MHz
coastal telephony band and the 4-27.5 MHz maritime
high-frequency telephony bands. The receiver is crystal
controlled and has a total of 78 channel facilities
distributed as follows: 30 channels in the coastal telephony
band and 8 channels in each high-frequency band except the 6
and 25 MHz bands each of which has 4 channels.
.The receiver is designed for reception of type A3, A3H and
upper-sideband A3A and A3J signals. It is fully
transistorized, and widespread use is made of integrated
circuits. These features in connection with the fact that no
crystal ovens are used cause the receiver to be ready for
operation immediately after having been switched on.
The receiver incorporates a monitoring loudspeaker, but an
external loudspeaker may be connected if desired.
Depending on the power pack installed in it, the receiver
can be powered from a 12V or 24V battery or from AC voltages
normally occurring in practice.
Adding new channels to the receiver is very simple. The only
adjustment required is adjustment of the crystal frequency.
The crystals become accessible after removal of the top
cover plate of the receiver. Crystal trimmer capacitors
permit making correction for the natural ageing of the
crystals which might otherwise within a few years bring the
frequencies outside the specification limits.