From the Service Manual:

Part Number Breakdown
The following is a breakdown of the part number used to identify this transceiver. Some
combinations are not available.
242-51FK-ABC-xxD
Model Breakdown

F Frequency Band


  • 2 - 380-470 MHz UHF-Low
  • 7 - 700-800 MHz
  • 8 - 800 MHz


K Keypad/IS


  • A - No Display, No Keypad (Model I)
  • B - Non-DTMF Keypad (Model II)
  • C - DTMF Keypad (Model III)
  • D - I/S No Display, No Keypad (Model I)
  • E - I/S Non-DTMF Keypad (Model II)
  • F - I/S DTMF Keypad (Model III)


A (Antenna)


  • 0 - No Antenna
  • 4 - UHF - 403-520 MHz
  • 8 - 800 MHz, 1/2 Wavelength
  • 9 - 800 MHz, 1/4 Wavelength


B (Battery)
  • 0 - No Battery Pack
  • 1 - Ultra High Capacity - NiMH
  • 2 - Alkaline Battery Clamshell
  • 3 - Ultra High Capacity - NiMH - Submersible
  • 6 - I/S Ultra High Capacity - NiMH
  • 7 - I/S Ultra High Capacity - NiMH - Submersible


C (Front Housing Color)
  • 0 - Black
  • 1 - Yellow
  • 2 - Orange
  • 3 - Black, Ruggedized Submersible
  • 4 - Yellow, Ruggedized Submersible
  • 5 - Orange, Ruggedized Submersible


D - 6 = 5100 ES Model, SEM/No SEM