Radius GR500 / R1225 question...

[EindhovenOne]

Hey, all. I have never really been into the amateur radio scene (I don't even have a HAM license or anything of the sort), but I told my friend I would help him get his little station setup at his place when everything he ordered arrived. I am very deep into the programming and service of the newer Moto portable radios and am in charge of such for two municipalities, but when it comes to these older radios I am at a bit of a loss. Here is my issue:

My friend ordered a used but fully working GR500 setup with the R1225 inside instead of the usual two-stacked Radius units. I programmed everything without issue and it seems like he got a good deal (and here comes a question I feel very stupid asking) but there are two coax cables coming out of the R1225 itself, one from the front and one from the back, and on the other ends of them is a much larger threaded connector like it is supposed to hookup to something that isn't there (I'm guessing that there used to be a duplexer in there but I cannot see where it would have fit) The third coax cable is the main one coming into the unit, also with the larger threaded end. My question is, if he has no need for a duplexer, what is supposed to get hooked to the main antenna line coming in and how to do so seeing as though I have three threaded male ends?

Thank you all for your time.

-E

[KB2ZTX]

Yuor correct the duplexer is missing and is needed for it to function effectively. You could use dual antenna but normally doesn't work well unless you have good seperation. Anyway the cable coming from the back of the radio is the transmitt antenna jack. the cable coming from the front of the radio by the ribbon cables is the receive antenna jack. all cables probably have N-Male connectors on them. I have a dozen or so of these in service. Work of caution the PA sucks on them. If its a 45 watt unit power it to 25 if its a 25 power it to as low as it will go

[Will]

If its a 45 watt unit power it to 25 if its a 25 power it to as low as it will go

Not really, the PA still dissipates LOTS of heat. Better to run no less than 35 watts, actual, and make sure the fan is working. On the 25 watt version, no less than 18 watts actual. Anything less the PA becomes very in efficient and gets just as hot or hotter.

The fan should have a thermistor lead make sure that is fixed on the PA heatsink. A little Artic Silver heatsink compound to make a good thermal connection to the thermistor.