Make repeater from CM300?

[sbennett1298]

I have a pair of Motorola CM300s. (VHF) I would like to join them together to make a repeater.
Where do I start? I have a duplex repeater cable, programming software and programming cable.
Not sure what programming I need to do to make this work.
Not sure duplex is the right cable.
I want to receive on one channel and transmit on another. Not visa versa.
Not sure what "Duplex" means in this context.
I just ordered this particular cable because it said "Repeater Cable" and works with CM300.
Does it matter if it is "Duplex"?

Thanks,
-s

 

[davidzimmerman]

have to ask what are you going to use the repeater for?

 

[sbennett1298]

To boost the range of EX500 handheld walkie talkies.

 

[davidzimmerman]

what frequency are you using now?

 

[jim202]

Building a repeater is not a simple task. The radios you use need to be well shielded, have good filtering and the transmitter needs a good heat sink and maybe a fan on the heat sink to keep it cool. The duty cycle of the transmitter duration is a major concern.

Most radios are not designed to transmit more than 5 percent of the time. In repeater service, this can at times go as high as 80 to 100 percent.

Another area to not skimp on is the coax cable used between the radios and the duplexor. This wants to be double shielded. No is the big word for using the low cost RG-58 cable that is so readily available. Then there is the antenna. Not all antennas are a good match for repeater service. Some antennas can kill the repeater to hear well. They actually can cause intermod issues. Then don't forget the feedline going to the antenna.

Some might say to use LMR type coax cable. This is also not a good choice due to the dis similar material used for shielding. There is an aluminum foil over the center insulator. Then right against the foil is the copper braid. Over time moisture will seep inside the cable and start causing you all sorts of noise when the repeater transmitter keys up. This problem is well documented in many places on the internet.

The next issue is the legality of using a REPEATER in the different classes of service. This comes back to the question what you were asked as to what frequency your planning to put this lash up on.

Step slow and careful on your plans for a repeater here. Not trying to put down what your looking to do, but just provide some guidance in the direction your trying to go.

 

[sbennett1298]

CM300 repeater

OK here is a little back ground about what I'm doing.
The short answer is "playing with a box of radios I got for cheap".
I have a crap load of EX500 hand held and CM300 mobiles I found at a flea market.
I have always thought HAM radio would be an interesting hobby so now that these radios
have fallen into my lap I have decided to get my HAM license and play around with them.
I have no plans to set up a repeater for community use so duty cycles or heat sinks are not a concern.
What I *might* do is build a repeater to put in my truck so I can extend the range of my hand held
while hiking....etc. So very minimal traffic. Just me and a friend or two perhaps.

I read something about desensing and duplexer so I gather that has to do with the TX radio interfering with the RX radio, Is the duplexer expensive and where do I find one?

Back to my original question....What is involved as far as programming the radios?
I know one radio will be programmed to TX on frequency A and the other to RX on frequency B
but are there special setting that specifically configure the radios to use the repeater cable connected between them? Do I need a cable that can control an antenna duplexer?
I gather that an antenna duplexer allows both radios to share one antenna to avoid interference?

P.S. This is not something I plan to do today or tomorrow. I'm in no rush. I plan to get my HAM license first so I will understand the legal issues before I get around to building anything. At this point I am just gathering info to get a general understanding. I have not picked a frequency yet but the radios are VHF.
-s

 

[davidzimmerman]

OK here is a little back ground about what I'm doing.
The short answer is "playing with a box of radios I got for cheap".
I have a crap load of EX500 hand held and CM300 mobiles I found at a flea market.
I have always thought HAM radio would be an interesting hobby so now that these radios
have fallen into my lap I have decided to get my HAM license and play around with them.
I have no plans to set up a repeater for community use so duty cycles or heat sinks are not a concern.
What I *might* do is build a repeater to put in my truck so I can extend the range of my hand held
while hiking....etc. So very minimal traffic. Just me and a friend or two perhaps.

I read something about desensing and duplexer so I gather that has to do with the TX radio interfering with the RX radio, Is the duplexer expensive and where do I find one?

Back to my original question....What is involved as far as programming the radios?
I know one radio will be programmed to TX on frequency A and the other to RX on frequency B
but are there special setting that specifically configure the radios to use the repeater cable connected between them? Do I need a cable that can control an antenna duplexer?
I gather that an antenna duplexer allows both radios to share one antenna to avoid interference?

P.S. This is not something I plan to do today or tomorrow. I'm in no rush. I plan to get my HAM license first so I will understand the legal issues before I get around to building anything. At this point I am just gathering info to get a general understanding. I have not picked a frequency yet but the radios are VHF.
-s

you still can't just pick a few VHF Frequency's to play around with that's WHY i asked what frequency?
i would Google How to make a Repeater do lots of reading you will need Programming Cables,Programming Software from Motorola Ect.

 

[sbennett1298]

ok will do.

 

[davidzimmerman]

I can extend the range of my hand held
while hiking....etc. So very minimal traffic. Just me and a friend or two perhaps.i would think just going hiking you would NOT be that far apart from your friends also i would check on what frequency's are in these radios. This is why i asked what frequency you never gave me a answer.

 

[davidzimmerman]

No MURS transmitter shall, under any condition of modulation, transmit more than 2 watts transmitter power output.There are five MURS channels and the channels are either 11.25 kHz or 20.00 kHz each. The channel frequencies and (bandwidth) are:NOT sure if your looking to use these MUR Frequencys?

151.820 MHz (11.25 kHz)
151.880 MHz (11.25 kHz)
151.940 MHz (11.25 kHz)
154.570 MHz (20.00 kHz)
154.600 MHz (20.00 kHz)

 

[nd5y]

Repeater operation isn't allowed on MURS even if the radios meet all the other rule requirements. See https://www.ecfr.gov/cgi-bin/retrie...sp47.5.95.j&r=SUBPART&ty=HTML#se47.5.95_12733

If you want to learn about building repeaters I would suggest The Repeater Builder's Technical Information Page™ as a good place to start.

 

[davidzimmerman]

Repeater operation isn't allowed on MURS even if the radios meet all the other rule requirements. See https://www.ecfr.gov/cgi-bin/retrie...sp47.5.95.j&r=SUBPART&ty=HTML#se47.5.95_12733

If you want to learn about building repeaters I would suggest The Repeater Builder's Technical Information Page™ as a good place to start.

i'm trying to help him and he will not say what 2 frequency's he's wanting to use.

 

[sbennett1298]

If you want to learn about building repeaters I would suggest The Repeater Builder's Technical Information Page™ as a good place to start.

Thanks for the link Tom.
For those who may have the same question I just found these links.

http://www.repeater-builder.com/motorola/manuals/rick-manual.pdf

HLN3333B R.I.C.K.

-Steve

 

[MTS2000des]

Aside from the other points made, these radios are NOT (as most mobiles) designed for the duty cycle a repeater operation places on them. Additional cooling WILL be required and even then, be mindful of duty cycle. These particular radios lack the physical heat sink for anything other than the rated 5-5-90 duty cycle.

 

[sbennett1298]

Aside from the other points made, these radios are NOT (as most mobiles) designed for the duty cycle a repeater operation ....

Good point! I was not aware of the duty cycle limitation when I first started looking into this.
It makes sense to me now why people kept talking about heat sinks and fans.

-Steve