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VHF CDM1250 no power output but RX is fine, Help??

Posted: Fri Nov 03, 2006 4:13 pm
by firecomm
I have a CDM1250 that doesn't have any power out on TX, but RX's just fine.

The radio was working fine, but now all of a sudden it doesn't even put out enough power to hit the portable 10 ft away.

The radio was NOT TX'd without an antenna so I don't know what the heck is going on. Was there an issue with certain CDM's just losing the PA??

I'm guessing that is the problem, anyone? the serial is 103TDLRxxx, if that helps.

Posted: Fri Nov 03, 2006 5:56 pm
by HLA
even if it was used with no antennae it would take some time for it to go out. and even with no antennae it should still go over 10 feet. put a meter across the ground and center pin of the antennae connector and see if it's been grounding out. if that serial number is right that radio is from June 2003 and it's just out of warranty, that sucks.

Posted: Fri Nov 03, 2006 8:04 pm
by ve3nsv
I had a CDM1550LS+ that had low TX power that I was able to bring back to life by doing the Auto Adjust PA Bias voltage in Global tuner under Transmit Alignment.

Posted: Sat Nov 04, 2006 6:11 am
by jackhackett
All we can tell from the serial number is when it was made, the model number would be more helpful, that would tell us what power level so we know what PA we're dealing with.

When HLA says put a meter acrossed the antenna connector to check if it's shorted he means the connector on the cable, not the one on the radio, just thought I'd clarify that.

With no power out the likely causes would be a bad final, or bad solder joints on the final. A bad antenna could cause either.

There is also a set of contacts on the circuit board that are connected by a rubber piece with a carbon contact in the cover, I believe that cuts of the PA when you have the cover off the radio, perhaps reseating the cover might help, although it's probably a long shot.

Posted: Sat Nov 04, 2006 2:05 pm
by firecomm
The model # is AAM25KKD9AA2AN, 45 watts correct?

This is the weird thing too, when I read the radio, the Tx Power settings were 20W Low, 53W High.

Would the high power setting have contributed to the radio possibly blowing?