kc0mlt wrote: > > > > Hello all, > > I am looking for some information on getting the maratrac to key up and > the audio connections into the radio wjen using it as a repeater > transmiter. I am powering it with a partial control cable and no control > head. I would like to be able to use the partial contorl cable for all > of the needed connections but I am willing to use the RJ45 programming > port inside the radio if need be. Any help with the connections would be > very appreciated! (what pin /wires, how to actually get the radio to > transmit -gnd the PTT???) things like that. >
I use a Maratrac as my UHF repeater TX. Interfacing is easy, with a couple of gotchas. First, the audio and PTT connections are easy. The RJ45 programming connector at the front edge of the radio uses the same pinout as most Radius mobiles. Pinout is here : http://www.batlabs.com/images/maxrad.gif Second, programming tips. The best way I have found is to program your unit for clamshell control head, and delete all modes (channels) except Mode 1, which is programmed to your TX frequency in both TX and RX. The gotcha is this: If you have an A7 (advanced) control head, DO NOT hook it up after you program the unit for clamshell. You will BRICK your radio, and I'm not sure if Motorola depot repair will take these radios any more. Instructions on powering the radio without a control head are here: http://www.batlabs.com/maratrac.html about a third of the way down the page. Basically, pins 17 and 13 to negative, and pins 19 and 4 to +12V. Make sure your power supply can handle the current draw at your power level. Speaking of power levels... TURN THE UNIT DOWN to about 60 watts (assuming you have a 100w drawer) and put a fan on it. This radio is not designed for continuous duty. Give it all the help you can. Don't go below 60w, as the radio will overheat due to inefficiencies in the PA. I've found that dialing back the power and using fans works well in a light-to-medium traffic machine. Oh, one more thing. The Maratrac uses a mechanical relay for TX/RX switching. The relay will last for a while, but it will eventually fail. I solved this by removing the T/R relay and running coax directly from the PA output out thru the hole left by the SO-239 connector, terminated in an inline SO-239. Of course, the antenna will no longer be connected to the RX, but hey... we're using this as a dedicated TX anyway, right? :) There you go. That should get you on the way to using your Maratrac as a dedicated TX. I hope anyone with additional info will chime in as well. 73's and good luck, Brian, N4BWP
