| Author |
Message |
    
Straycat
| | Posted on Saturday, June 21, 2003 - 12:33 pm: | 
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I recently acquired a Uniden PX122XL. Talks great and swings good too. When I went to change the mic and try a new one I noticed that the back of the radio where the final is was VERY hot. I let it cool down and opened it up. All looks good so I backed the dead key to 4 watts and it now swings to about 13. It modulates even better ( it was set to key 7 abd swung to 13 before). It still gets hot though. What's the deal ? Is there something to look for that a tech might have done to cause this ? |
Kc0gxz
| | Posted on Sunday, June 22, 2003 - 7:21 pm: |
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Straycat
Check the Bias on the driver and final. If the Bias is set too high, the finals WILL overheat. Some people think that the Bias controls are just another pot to turn up to get more power from the radio. They are not limiters. They are there to control current to the finals only.
The PC-122 does not have a micgain on it. Try turning your mic down a bit so you are not driving the radio so hard.
73s
Jeff, kc0gxz |
Straycat
| | Posted on Sunday, June 22, 2003 - 9:49 pm: |
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Thanks Jeff, I'll try adjusting the final bias. The radio has a stock mic so I can't turn that down. |
Bigbob
| | Posted on Sunday, June 22, 2003 - 10:16 pm: |
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Good point.I've got a pc122 and it get's hot and the radio was realigned by a competent tech it just don't have the heat sink area of bigger radios.The whole back is aluminum and there's a folded aluminum heat sink inside above the final,I placed the heat-sink on the outside using heat sinkgrease,used a hole saw on the case to add cooling air to inside of radio and covered holes with fiber glass screen cloth,warm not hot,its been running 12 years,never replaced anything. |
Kc0gxz
| | Posted on Monday, June 23, 2003 - 10:39 pm: |
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Bigbob
You must really love that old radio to go to all of that bother. And I hope your old PC-122 appreciates you for bringing its blood pressure down to a comfortable level.
73s
Jeff, kc0gxz. |
Bigbob
| | Posted on Wednesday, June 25, 2003 - 10:08 pm: |
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Oh,it does,it does,yep yep yep. |
Bigbob
| | Posted on Wednesday, June 25, 2003 - 10:12 pm: |
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I put a small fan on my dx2517 power trans. heat sink to,cool as a cucumber. |
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