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Texas star dx 350 staying hot when off?
- Thread starter rflegacy
- Start date
Well, nomad is right, if the amplifier heat sink is getting / staying hot, then that means the heat is being generated by the RF power transistors.
It would be prudent to check the transistors bias resistance first, then do a quick check of the transistors bias voltage.
It would be prudent to check the transistors bias resistance first, then do a quick check of the transistors bias voltage.
It's never oscillation. It's always a broken bias circuit or bad pills
Disconnect the bias choke going to the bases. See what happens. Does it have bias? Have you checked?
He mentioned that the meter light goes out when it's unkeyed. Being as the light gets voltage from the same switched source as the bias supply, I doubt the bias supply is staying on.
But something is.
Simply lifting the base lead of all four transistors from the foil pad should stop the renegade current drain.
If it doesn't, there's one or more failed transistors.
If this DOES shut down the renegade receive current, next measurement to make is the voltage to ground at each of the foil pads where a transistor base lead was lifted away. Should be zero. If not, it's coming from somewhere.
Troubleshooting any kind of short circuit consists of taking things loose until the fault current is interrupted.
73
Why not simply determine what is heating when off? What component(s) are HOT to the touch or thermometer?
Shadetree Mechanic
Delaware Base Station 808
Seems to me he said the heat sink gets hot. Only the RF power transistors will raise the temperature of the heat sink.
73