TNC Pi and Motorola Maxtrac

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W3AWF

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Has anybody ever interfaced a TNC Pi with a Motorola Maxtrac? I'm trying to set up a transmit only radio for my weather station to be interfaced with our county weather station system. Also looking to use one as my primary Digi.


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petnrdx

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I have not used, nor have I any knowledge of the TNC Pi, but I have interfaced dozens of Maxtracs to many different TNC's and sound card interfaces.
It should be pretty simple and work with pretty much any TNC.
 
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Transmit only, you can interface through RJ-45. A TNC-Pi uses the same pinout as a KPC-3 on the radio side. However, best practices would encourage the TNC being able to check for channel activity prior to transmitting. All you could ever want to know about the Maxtrac can be found on the Repeater-Builder site.
 

petnrdx

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As mentioned, you should at least have the radio "hold off" transmit while there is activity on the channel.
Maybe you planned that, but if not, most of us I believe are going to recommend that.
As for Maxtrac connections, yeah, all you could ever want to know is on Repeater-Builder or Batlabs.
To save hunting:
KPC-3 function Maxtrac MIC Maxtrac logic board J8 if 16 pin logic board
1 Tx aud 5 12 2
3 PTT 6 11 3
5 RX aud 8(fixed level) 4 11
6 gnd 4 10 7
6 hang up button 3 13 not available
COR if needed 8

Note that many Motorola products number the mic pins backwards. The above list for the Maxtrac mic numbering is looking at the FRONT of the radio, the release notch is to the right, contact pins to the left, number 1 is at the top, 8 at the bottom.

And as usual, check these for yourself prior to hooking up, I am not responsible for errors, just trying to help.

I like using the logic board J8 connections as I can solder direct to the pins ( one less connector to buy and possibly go bad. And those connections work with the old (cheaper) 5 pin logic board radios.
 

petnrdx

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Crap.
That didn't work well.
The website removed all the spaces.
If you extrapolate the lines and accept that each number should move to the right to line up under the "labels" in the line starting KPC 3 you should be able to figure it out.
 
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