Uniden UM415 Oceanus D Radio

[capav8r]

Hello all. I received my new Uniden UM415 VHF radio today. I took it out of the box and headed for my bench. I connected it to a 12VDC power supply, wanting to make sure it works. Unfortunately, it does not seem to. It is getting power, but there is no display. The speaker is actually acting like a PA. Sound from the mic is very faintly being reproduced on the speaker, without the push to talk being pressed. I do not have an antenna connected and am wondering if the radio has some sort of internal protection that prevents it from powering up without an antenna connected. I highly doubt that this is the problem, but thought I would throw the question out here before sending it back. I did try placing a 50 ohm resistor across the antenna output. I was also very careful not to press the push to talk button without an antenna connected. My boat is an hour away in a storage building that I do not have ready access to, so I cannot get to my antenna. I am just wondering if anyone has a definitive answer on this through past experience.

Thanks!!

[seapuppy]

I would say that there is definitely a protection circuit built in...if the antenna isn't attached..then it probably won't do anything...but...I'm no RF expert...but if your not even getting a face plate activated..then I'd say there's something wrong....but that's just me..


keep us informed...

SP

[iceman]

Cap -

It doesn't sounds like the radio completely powered itself down, since you heard the audio from the mic. That was probably a small amount of internal cross-coupling between transmitter and receiver, normally un-noticable. Anyway you terminated the antenna with 50 ohms, which would look like a normal antenna load to the radio. You were right to not key the mic, though.

If the display didn't come on, the digital circuits weren't happy. Are you sure your power supply was beefy enough? Can you measure the DC voltage when you try and power on the radio? If it drops below 11 volts or so, it probably wouldn't work right and behavior would be a bit erratic (some things working and others not).

[capav8r]

Thanks for the info Ice. I was actually using one of the batteries from the boat. It was showing 13.79 volts with the radio turned on and 13.81 with it off. That tells me that the radio is drawing some power. There is not even back lighting for any of the buttons turning on. The only indication that the radio is receiving power is the faint sound from the speaker and the slight drop in battery voltage when turning the radio on. I did actually meter the resistor this morning and it is showing 60 ohms, not 50 as the bands indicate. Which leads me back to my original thought-does the radio prevent powering up without an antenna/true 50 ohms? My next step is to find a resistor that is truly 50 ohms. At this point, I am 90% thinking I have a bad radio. Of course, Uniden tech support is closed until Monday.

[capav8r]

I made a trip to the boat yesterday so I could try it with an actual antenna connected to it. No change. It is dead.