Narrow band transmitter 70TX-LM

The 70TX-LM is a low-cost 10 mW FM narrow band multi-channel radio data transmitter according to EN 300220. The module is realized as a synthesizer and allows operation in the European ISM band from 433,100 to 434,700 MHz on a total of 8 channels without a fixed raster. The transmitter reaches its full power already at 2.3V.

The internal microcontroller generates from the information of 3 solder bridges (3 bit data word) a serial data protocol which sets the desired channel with the help of a synthesizer. There is no need for a complicate programming. On customer request we can program the module with 8 arbitrary frequencies. The 70TX-LM(E) transmitter basically covers the frequency range from 430 to 440 MHz.

If the frequency should be changed during operation, the variant 70TX-LME is suitable. With this module the 3 data bits can be changed externally via the extended pin header (7-pin instead of 4-pin) by means of a DIL switch or a uC. Short switching times predestine the module even for frequent frequency changes (see further details under multi-channel transmitters).

In contrast to other transmitter modules in our program, the modulation is exclusively tuned to digital data. For transmission of analog data, please use the more universal 10mW transmitter modules 70TX-M1 (single channel) or 70TX-S (multi-channel).

In combination with the 70RX-M2 or 70RX-S2 receiver modules, long-range radio systems can be set up for simplex or half-duplex operation. Together with our remote switching module FSM24, the free field range is about 1400 m.


  • Narrow band single channel transmitter
  • 1 of 8 preprogrammed channels (fix)
  • 10mW output power
  • Typical range 1400m
  • Super small size
  • Less current consumption
  • Data rate 100 - 4800 Bd
  • Suitable for digital data only
  • No licence required
  • Compliance to RED (2014/53/EU), EN 300220


  • Remote control systems
  • Industrial applications
  • Telemetry systems
  • Alarms
  • Security systems


Communication Simplex
Frequency range 433,100 - 434,700 MHz    (8 channels)
  optional 430 - 440 MHz
Number of channels Single channel (fix)
Output power 10 mW / 10 dBm at 50 Ω
Modulation FM narrow band    (digital data only)
Data input level 5 VPP (TTL)   
Deviation ± 2.4 kHz  (± 50 Hz)
Data rate 100 - 4800 Bd
Temperature range -25°C . . . +75°C (TCXO)
Supply Voltage 2.3 - 5.2 V    (max. 2.2 - 5.5 V)
Supply Current 24mA (± 1 mA)
Dimensions 22.0 x 13.8 x 6.0 mm 
Weight 5 g
Material stainless steel
Antenna connector pin header
Approvals RED (EN 300220)  for  Europe (433,100 - 434,700 MHz)

Data sheet 70TX-LM (10mW, single channel)

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