Today a went to a friend that has a lab PS and as expected it showed a short cutting in regulated 0,5A, obvious too much for the bias line, even with the predriver taking from TX13.5V. All was tested very provisionally. Short voltage was 3V, similar as measured in RF Unit Q01 when connected there. And consistent with 20 Ohm measured in PA TX13.5V line.
Next step is to work comfortably. I guess I have to cut the mod that gives volts to PA predriver, then cut regulators, and in the end start destroying tantalum capacitors on 13,5V. Job for Freddy Krueger, cut and test, cut and test.
I hope in some moment the intensity goes to normal. Some mA for bias and maybe 200mA for predriver.
I am not testing 13.5V line to drivers. I have seen a repair with blasted tantalum in TX13.5V. The one in the 13.5V (drivers collector) was changed too. Leaving the ones in 8V and 0.7V. In case the problem are the capacitors, I think I will change the one at 8V between both regulators 13.5>8>0.7V to vias.
73 EA1FC
