RIM232-173 VHF Radio Modem

Select Frequency


The RIM232-173 Radio Modem provides a reliable wireless communications link between two serial devices. The RIM232-173 can be used in a variety of data communications applications that require a simple to use invisible data link.

Repeater mode enables the Radio Modem to extend the effective operating range of a point-to-point link by forwarding data packets over 1 repeater hop.

The Radio Modem uses unit & site addressed data packets with error checking and packet acknowledgements to achieve a well managed highly reliable wireless link.

Configure the RIM232-173 for point-to-multipoint broadcast mode and combine with any number of intelligent host computers/controllers to implement very large networks.

The RIM232-173 Radio Modem supports a range of built-in diagnostic functions that can be used for network interrogation, network problem finding and radio site & range testing.


  • Addressable Point-to-Point, Point-to-Multipoint  and Broadcast Multidrop
  • Licence exempt operation on 173.225MHz & 173.250MHz
  • Serial protocol. 8 data/1 stop/ no parity
  • DTE Speed selectable 300-57600bps
  • Air data speed selectable  300-2400bps
  • DTE flow control - hardware/software/none
  • 96 byte serial receive/transmit buffer
  • On-air data encryption and 100% code balancing
  • Range up to 4km outdoors
  • Simple built-in command line configuration
  • Built-in RF link diagnostics
  • Remote over-air unit configuration
  • Front panel modem status indicators
  • Low operating current. Auto standby mode
  • Low profile enclosure with integrated PP3 battery.
  • DIN rail mounting option.
  • Uses 9V PP3 battery or 7-15V DC power supply.


  • Operating voltage of 7 to 15VDC
  • Average current of 36mA (data streaming).
  • Standby current of 15mA.
  • Shutdown current of 440uA, for long-term battery operation (DTR activated).
  • Physical: Width 62mm, Depth 24mm, Height 103mm. (excludes antenna)
  • Operating temperature of 0 to 55 degrees C


  • Radio approval EN 300 220-3,
    EN 300-489-3, AS4268.2 
  • 173.250 MHz centre frequency
  • Transmit power: 10mW standard
  • Transmit power: 100mW /SH
  • Receiver sensitivity -116dB for 1ppm BER
  • Standard aerial: SMA female connector


The following table outlines the nominal operating range of the RIM232-173 Radio Modem. Please note that the ranges listed will vary depending on the level of surrounding RF interference, obstacles near or in the line of sight and other environmental factors.

Model and Antenna


Outdoor (1)

RM232-173/S - Half wave dipole


2 km

RM232-173P/S - Half wave dipole


4 km

1. Outdoor range testing performed in a rural environment using a ground independent half wave dipole antenna.
2. In ideal conditions a functional range double those quoted have been achieved. Antenna A mounted 12m with line-of-sight to antenna B at 4m.

Product Features