UBC 780 Help needed

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Newage

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May 21, 2008
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Stanford in the vale, oxon
Hi All
I'v just picked up a UBC 780, and to tell the truth it great but I do have a small problem.
After the unit has been on for 2-3 hours the sound quality seems to get degaraded.

When the unit is first on the sound is crisp and clear, but ends up sounding like ATC are talking in to a "bucket", but the signal strength is still showing max.

The scanner is linked to a disk cone mounted on the roof, this feed is split so I get a feed to my SBS1 box, I also have a pre amp in the main line.

I'm thinking this may be a heat issue, any thought would be welcome.

Cheers Mike
 

KE5MC

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Dec 19, 2002
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Lewisville, TX
Sounds like “no pun intended” something in the audio output stage and heat related. An IC or capacitor is shifting characteristic with temperature. Freeze-mist is often used to cool individual components to find the offender. Use it sparingling to avoid cooling more than one component or you end up replacing the wrong device.

There is an audio mod that increased the output by reducing the value of a particular resistor. I have never heard of problems with the increased output, but Uniden’s design limited the audio for a reason. My 780’s stock output has plenty of output for the environment I use it in. Maybe yours was modified and the audio output stage is overheating. I don’t know any of the details of the mod, but they can be found on the Internet.

mike
 
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