BOS radio
DH4PY

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  SEM 27-820 GWL

was built by Standard Elektrik Lorenz.
It is a BOS radio in the 4m- band for mobile or fix station use.

240 channels, 120 each in the upper- and lower band are used.

A 10-watt-amplifier for loudspeaker announcments is built in.

All operational elements and the loudspeaker are situated on the front panel; connectors for battery and announcment- speaker are on the right side.


The circuit:

The radio is an excellent example of using several generations of active elements in one radio:

  • Tube in Noval Technique (QQE 03/12)
  • Tubes in pencil technique (EF 732.....)
  • Ge-transistors in glass housing (OC...-types)
  • Ge-transistors in metal housing (AF...-types)
  • Si-transistors in metal housing (2N....-types) "

    Frequeny range:
    Lower band 75.275 .. 77.655 MHz (channels 400U to 519U)
    Upper band 85.075 .. 87.455 MHz (channels 400O to 519O)

     


    Technical data:
    Channels:
    240
    Channel spacing:
    20 kHz
    Changing of bands:
    By the switch Oberband / Unterband
    HF- output:
    10 W
    HF- impedance:
    60 Ohm unsymmetrical
    Mode:
    F3 (FM)
    Call tones:
    1750 and 2135 Hz
    Squelch:
    Can be switched off
    NF- frequency:
    300 ... 3000 Hz @ +1 ... -3 dB
    Receiver sensitivity:
    0.5 µV @ 20 dB
    NF- output:
    Loudspeaker built in 0.8 W / 5 Ohm
    Announcment loudspeaker 10 W / 15 Ohm
    Powered by:
    Version I: 6 or 12 V, switchable
    Version II: 12 or 24 V, switchable
    Power consumption @ 12 V:
    Receiving 1.2 A; transmitting 5.3 A
    Active elements:
    50 Transistors, (35 Germanium)
    35 Diodes
    3 Zenerdiodes
    5 Tubes
    22 Crystals
    Measurements and weight:
    H 90 x B 290 x T 470 mm; 12 kg