SEM25 VHF Vehicle Radiotelephone
The transmitter/receiver set SEM25 has a range of approximately 30km. It operates in the 26
to 70MHz frequency band and provides 880 channels at 550kHz spacing. Any ten preset channels
can be selected by means of a switch.
The transmitter output is switchable to 1 or 15 watts. Transmitter and receiver use frequency
modulation (F3) and operate on the same frequency. The operation mode is simplex.
The set is designed for installation in motor vehicles and is powered from the 24-volt radio or
vehicle battery. In conjunction with another SEM25 or SEM35 set it can be used for relay operation.
By the use of additional devices the application can be extended to include interphone communication,
internal-external communication, and local to remote-control.
The set, which is a plug-in modular construction, is contained in a sturdy watertight light-metal casing,
and arranged on a shock-absorbing mounting. The mounting also carries the power supply modules and the relay insert.
The transmitter/receiver is controlled from a seperate control unit for detached installation which carries all the required control elements.
The possibility of locating the control unit as much as 10 metres from the transmitter/receiver allows the radio
set to be mounted at any convenient place in the vehicle. The control unit, which is considerably smaller, is mounted
within the reach of the operator who is thus able to recognise at a glance the state of the equipment.
The antenna tuning unit provides optimum matching of the antenna to the transmitter/receiver for the
adjusted frequency. Connection is established via a multi-conductor cable.
The SEM25 can be complimented by the additional receiver EM25 on a separate mounting.
The features and technical data of the additional receiver are the same as those of the
SEM25 receiver part, except that the case is smaller. For controlling the EM25 the same
control unit isused as for the SEM25.
Developed in the early 1960s under a Federal German Government contract and entered service
in 1964 with the Federal German army. Still in production but scheduled for replacement by SEM80/90.
Frequency range: 26-69.95MHz
Channel spacing: 50kHz
Number of rf channels: 880
Transmitter rf output low/high: 1/15W
Frequency deviation: +/-10.5kHz
Receiver sensitivity for (s+n)/n: 10.5microV for 20dB into 50 ohms
Af otput: 50mW
Power supply: 21-29V
Manufacturer: Standard Elektrik Loranz AG, Stuttgart (this info from a sales brochure on the SEM25)