100 Watta Spectra Power drop off

[KitN1MCC]

one of my customers has a 100 watt a9 spectra in is plow truck. radio will work fine then after a while of using the radio the Power drops off to nothing checked fuses looks ok i am gonna put the SWR on the antenna if the antenna is good any ideas could it be a cap issue

[Will]

It could be a problem with the PA overheating and getting cut back by the power control circuit. Excess SWR can cause the same cut back.

Leaking or allready leaked caps can do this too.

[KitN1MCC]

Antenna checked out fine i am gonna have to pull the draw out. it was not warm to the touch

[35echo]

One possibility is a cap on the command board. It is labeled 10uF 50v in the left rear area. It is the larger of the four electrolytic caps in this area. If it leaks it can cause trace and intra-board passthrough damage. The power control circuitry runs through this area also. Another possible cause is a stressed driver amp on the pa deck.

Regards

[Jim202]

I would try measuring the +12 volts going to the PA section. In trucks where dampness is a factor, poor
install practice often proves to be a downfall. Splices get wet and cause the crimp connections to go bad.
Under no load, the 12 volts looks good. Pull some current and it goes away or drops way off. Before
you pull the radio, try a voltmeter and see just what is going on. Poor connections at the battery will do the same.

You may still have to bench the radio, but you at least will know if the heavy 12 volt feed is any good.

Jim

[KitN1MCC]

yeah i am gonna check the power leads again. put a meter on test at transmit