[arm-allstar] Success with Remote Base Channel Steering (Motorola CDM1250/RB USB-RIM-Lite)

[Les Bradshaw]

👍


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On Sunday, April 8, 2018, 4:48 PM, Lloyd Duck via arm-allstar <arm-allstar at hamvoip.org> wrote:

Randy, 

Glad you had the same success I did. Scott has made great hardware and Doug did a great job on the software! 


On Apr 8, 2018, at 4:02 PM, Randy Neals via arm-allstar <arm-allstar at hamvoip.org> wrote:

A quick note to report good success with Remote Base Channel Steering.
I have used a Motorola CDM1250 VHF radio, appropriately programmed with 3
channel selection lines on the 20 pin option connector.

The Channel Steering how-to-note on the HamVOIP page was super helpful, and
I now have a VHF remote base with 7 steerable channels. (1-7 on the radio)

The key to making this easy was the Repeater Builder USB-RIM Lite "Maxtrac"
edition and the Motorola CDM series radio. Plug and play.
http://www.repeater-builder.com/products/usb-rim-lite.html

The USB-RIM Lite (Maxtrac) has GPIO 5,6,7,8 connected via buffer
transistors to pins 6, 8, 14 and 12 on the 20 pin option connector on the
CDM1250.  (16 pins on a maxtrac)
I'm using one line for COS, and 3 lines for radio channel steering.

The CDM1250 uses BCD (binary code decimal) control lines for channel
steering.
The AllAtar channel steering script translates DTMF input to specific bit
pattern on the GPIO and radio control lines.

Following the example, I've configured the function stanza using 83x
So if I want channel 1, I send DTMF *831, channel 7 is *837 etc.

If you have ever considered a remote base on your repeater, or even an
Internet remote base - This is a slick and easy way to implement.

Why am I using a CDM1250 instead of a Maxtrac?
The CDM series radios have a varactor tune receiver front end. As you
change frequencies, the selective front-end retunes its narrow passband for
the frequency you are operating on. The Maxtrac series have a fixed tuned
wide front end nominally 24 MHz wide. I've found the CDM series to be a
more selective receiver, less susceptible to interference.

73
Randy
W3RWN
Seattle
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