CDM1550 LS+ Not transmitting but very brief second

[Marine_Michael]

I have a couple CDM1550 LS+ in UHF and have programmed them with GMRS frequencies. Channels 1-22

It receives without any issue on the channels.

When I try and transmit I can get a brief (very very brief) transmission out before I get a tone back from the radio and all further transmissions are stopped. It will break squelch of the other test radios on the correct channels but will not transmit out once that tone comes back.

At one point someone helping me suggested it was an LS trunking error as if the radio wasn't authorized on the net that was programmed for and would stop transmitting. I am not trying to use trunking nor would I want to use trunking.

I just want basic GMRS capability on a few conventional channels. Could I get some feedback on possible areas or settings to review?

 

[R8000]

assuming your programming is correct.....

1. Power supply issue - check connections, voltage and current capability
2. Antenna issue - try a dummy load see if it goes away
3. RFI getting back into the radio - relocate antenna away from radio/power supply
4. Internal error/ Failure of the radio (doubtful)

 

[methusaleh]

assuming your programming is correct.....

2. Antenna issue - try a dummy load see if it goes away

That was my first thought; bad SWR and/or the coax not quite making a good connection.

 

[SteveC0625]

I have a couple CDM1550 LS+ in UHF and have programmed them with GMRS frequencies. Channels 1-22

It receives without any issue on the channels.

When I try and transmit I can get a brief (very very brief) transmission out before I get a tone back from the radio and all further transmissions are stopped. It will break squelch of the other test radios on the correct channels but will not transmit out once that tone comes back.

At one point someone helping me suggested it was an LS trunking error as if the radio wasn't authorized on the net that was programmed for and would stop transmitting. I am not trying to use trunking nor would I want to use trunking.

I just want basic GMRS capability on a few conventional channels. Could I get some feedback on possible areas or settings to review?

If you search around the net, you will find that inadequate power supply is the #1 cause of the symptom you describe. The radio draws more power on transmit than it does on receive. With an inadequate power supply, it will receive just fine, but when you key it up, it wants more current. When it senses that added current is not there, it beeps and stops transmitting.

For this radio, if it is the 25 watt rf model, your power supply should be capable of supplying at least 10 amps continuous. If you have the high power model (40 watts of rf), the power supply must be at least 15 amps.

 

[Marine_Michael]

You guys nailed it. I didn't have enough current going to the radio and once I turned that up then I was able to resolve the problem. Thank you all for your help. I was chasing a rabbit but you all provided a fresh prospective and solve my issue.

 

[N4GIX]

You guys nailed it. I didn't have enough current going to the radio and once I turned that up then I was able to resolve the problem. Thank you all for your help. I was chasing a rabbit but you all provided a fresh prospective and solve my issue.

I have a pair of the CDM1550 LS radios for a portable repeater. I've installed a 30amp switching supply to run both radios, and also provide enough capacity to keep the gel-cell batteries charged.