Got a Ranger RCI-69 (1st edition) on the desk today.
Reason for being on my desk:
Blowing finals not long after being replaced.
Evaluation:
The last final (RT1) shorted and next to last final (RT1) weakened, then popped.
I've replaced these mosfets once before about 2 months ago, then the user stated he had an issue with the input of his amp and it took out those new finals. I just replaced those mosfets again, keyed up for a brief second and pow, it blew the last final in the chain again. Each time I replace finals, I always reset the bias before testing it, as I did this time also. The bias sets great, but once you reattach the bias jumpers and key up, pow it blows a final, as if it sees an immediate high SWR, but my external meter shows a perfect SWR from my dummy load. When it blows a final, the radio immediately shuts off and the power supply won't come back on unless you unhook the DC supply feeding the main board.
Any advice guys/gals?
Reason for being on my desk:
Blowing finals not long after being replaced.
Evaluation:
The last final (RT1) shorted and next to last final (RT1) weakened, then popped.
I've replaced these mosfets once before about 2 months ago, then the user stated he had an issue with the input of his amp and it took out those new finals. I just replaced those mosfets again, keyed up for a brief second and pow, it blew the last final in the chain again. Each time I replace finals, I always reset the bias before testing it, as I did this time also. The bias sets great, but once you reattach the bias jumpers and key up, pow it blows a final, as if it sees an immediate high SWR, but my external meter shows a perfect SWR from my dummy load. When it blows a final, the radio immediately shuts off and the power supply won't come back on unless you unhook the DC supply feeding the main board.
Any advice guys/gals?