Hi Steve
There are 2 voltages 2.81V and 8V mentioned on circuit diagram. The 2.81V appears as a voltage divider and feeds gate through a resistor and the 8V appears at drain through a couple of resistors.
Is it possible to measure these while pressing on board to see if they change during fault condition.?
As for question re tab of the driver device, it is not mentioned in data sheet if connected nor in picture. With the radio off you could try doing an ohms measurement between the tab and the 3 pins to see if any are connected. Try applying the pressure during this check as well if possible.
Are you able to take a closeup photo of this area of the board to show us please.
Hope this is of some help.
73
Neil
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On 26 Nov 2024, at 9:12?PM, Steve G4ALG <steve@...> wrote:
?
Neil ZL3ADC: Thank you.? I'll do the fan modification once the rig is working again.
To All:
Regarding the pre-driver device Q102, RD01MUS1.? ?This device seems to be most sensitive to tweaks of the PCB, but I have been unable to positively isolate the fault to Q102 with it still being soldered to the PCB.?
It would be helpful to know whether the device's Source connection is internally bonded to the Tab connection.? ?Both get soldered to ground on the PA Unit board.? ? I have found a data sheet at:
But it is not clear to me how to use the data sheet to ascertain whether the Source is internally connected to the Tab.? ?I would appreciate some help on this point.? Of course, if you have a RD01MUS1 on hand, I'd appreciate your observations with a test meter!
73
Steve G4ALG
