Problem with UHF transmission

[Frenchie]

Hi All,

I have a Uniden UH-013 with a ground independent antenna mounted on the bull bar (sorry can't remember the brand but it was a well reviewed one at the time). I seem to be able to receive okay but have always had issues with transmission. If I have someone standing 50m away with a hand held I can hear them but they get nothing when I transmit, and all I get is a loud screech.

Any ideas?

Alternatively does anyone know of a good specialist in Hobart where I can take it for a diagnosis?

Thanks Tony

[AK83]

I suppose the obvious question is;
what's the condition of the coax to/from back of Uniden to antenna looking like?
Any kinks? Does it pass through any unprotected access holes where it may have rubbed through and torn/worn the sheath?

[rovers4]

Time to check that the shield braid in the antenna lead is in good nick. Ensure there are no gouges where water can get in. It needs to be insulated from the inner, but well connected back to the radio. And it must connect to the outer part of the actual antenna.
Make sure all connectors are clean and done up at least as hand tight. No need for a heavy hand on the multi-grips though.

While checking connections, look for any sus power connections in both the positive and negative lines.They should be clean and firm. Make sure the size of wire is adequate.

If no fault found, try another radio in your car , and also try your radio in another car. See whether the problem stays with your car, or goes with the radio.

[AK83]

could also be something as simple as a dead/dying microphone too.
if you still have access to that handheld, can you induce feedback by holding the handheld close to the mic on your Uniden?

Handheld set to the same channel as your radio, handheld close to the mic of your radio and using your radio to transmit, just press the PTT button. You should hear feedback from the system.
If not, probably a microphone issue.
To be sure, doing the same thing with the radios, transmit with the handheld and it should induce feedback.

[Graeme]

Something else to check - if you can't hear the handheld when it's several hundred metres away but have line of sight then that's a fair indication that your antenna or cable is faulty. However nothing better than checking for continuity of the signal and shield and lack of short circuit between them using an ohm meter.

[AllTerr]

Quite possibly the mic. I have the same unit and had the same problem and that's what it was.

[Frenchie]

Thanks for all the suggestions, it certainly gives me somewhere to start. [smilebigeye]

I'll let you know what I find.

[Redback]

Thanks for all the suggestions, it certainly gives me somewhere to start. [smilebigeye]

I'll let you know what I find.

It's only a simple thing but have you looked at the connection of the mic to the radio and made sure it's screwed in tight, I've made that mistake[bigwhistle]

[I Love My Landy!]

I had a similar problem with my GME. It would receive fine but would not transmit any meaningful distance. I replaced the amplifier (or 'RF module' to be specific) and now it transmits fine. It was a $25 part ordered off the net, and it wasn't too difficult soldering it in place.

Edward:)