The Bendix/King LPX2101 is an 800 MHz, LTR-capable handheld radio. Although there are many newer radios on the market which are lighter and more compact, the B/K radios can be obtained very inexpensively on the used market.

Little documentation on the operation and programming seems to exist on the internet at this time. This FAQ is an attempt to rectify that problem.

A good deal of information is available on LTR trunking. I do not attempt to cover the concept here.

This information is my first effort at compiling what little I've learned. Use with caution: my observations may not be correct. I welcome corrections! Please drop me e-mail with additions, comments, and/or corrections. Thanks!

Using the LPX2101

The radio has 3 knobs:

Additionally, there are two toggle switches:

Systems: A, C, and 1 through 8. These are systems of repeaters. Evidently Bendix/King thought that LTR systems would be quite prolific and wanted this radio to be useable on many different systems in the same area. LTR systems are few and far between; I doubt that any user would ever belong to more than 2 in the same metro area. But, this radio can belong to 8.

Groups: 0 through 9. On any system, you may belong to up to 10 groups. Think of these as different channels in the same area, or perhaps different PL (i.e. CTCSS) tones on the same frequency. If you're running a hotel system, you might have the following groups:

  1. Maintenance
  2. Security
  3. Grounds
  4. Room Service
  5. Bell Hop
  6. Transportation
  7. Conventions
  8. Ballrooms
Quite simply, if you want to talk with a Security staffer, you switch to Group 2. All members of the Security staff would hear you, but none of the Grounds staff would.

  • A: Stands for talkAround. If the radio is programmed with "conventional" frequencies (no LTR), talkaround switches the transmit frequency to be the same as the receive frequency (assuming that they're different).

  • C: Stands for Conventional. If the radio is programmed with "conventional" frequencies (no LTR), the radio transmits and receives with the programmed frequency and PL/DPL. No trunking occurs in this mode.
  • Programming the LPX2101

    To program this radio, you will need the following:

    Hints: OK, so I'm not an expert at programming this radio yet. So I'll share the hints you need to start your own learning:

    1. Make sure that the serial port is available to talk with the radio. Remember to turn off your Palm Pilot HotSync Manager and other applications that grab the serial port.
    2. The MOBILNV program does not work under newer WinOS (Win2000, WinXP), so you'll need to go back to a Win9X or DOS machine. Symptom of a non-compatible PC: The serial interface would not get set to the correct speed. There was no other indication anything was wrong except it did not program the radio.
    3. The radio's System knob must be in position 9. Yes, I know that's not a numbered position. You will need an allen key to allow the knob to be lifted over the stop pin.
    4. In the software, frequency information is not directly entered in MHz, but instead uses Motorola "channel numbers." The frequencies are in "FCC #" which is not the ones in the latest part 90. Channel 601 is 866.0125 add 25KHz for each step making it 40 steps/MHz so 641 is 867.0125.
    5. Conventional Analog is under system # 9 in the programming screen. Be sure to hit the ^R to go to the next screen and the CTCSS tones can be programmed there.
    6. With a CTCSS tone programmed in the RX requires the tone. To bypass the RX tone, flip the "MON" switch. It will then be squelch activated.
    7. When you want to read the radio, initiate the read in the software. It will ask if the radio is ready. Answer yes. Then, momentarily key the transmit button. The radio will then begin to transmit data to the PC & program.

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    Updated on 27-Apr-2004