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
Little documentation on the operation and programming seems to exist on
the internet at this time. This FAQ is an attempt to rectify that
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:
Group -- 0 through 9
System -- A, C, and 1 through 8
Additionally, there are two toggle switches:
Mon -- Off and On. If listening in conventional mode, turns off the
requirement for PL receive. If listening in trunked mode, ??
Scan -- Off and On. This does the expected thing with one
exception: if scan is on, TRANSMIT will be on the last frequency
heard! This can be disconcerting.
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:
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).
- Room Service
- Bell Hop
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:
- PC running DOS or Windows and a working serial port
Your Bendix/King LPX2101 radio
Software. This is available on the net. You want Mobilnv.exe, which is
sometimes distributed as a package called 800_edit.exe.
A Bendix/King programming cable
These instructions. If you find better instructions, please share them!
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:
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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.
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.
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.
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
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.
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
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