This is a drawing of the voltage & current sensing board. If you look further down on my site, this is the board on top of the rf-deck with red wires going through blue hall-effects elements. There is some more stuff on this board, and this is the VDD FET switches, but these are not in detail in the drawing.
Last night, during light burn-in tests, the amplifier suddenly dropped gain.
No alarms, no nothing, but one of the MOSFETS was drawing a lot less current compared to the other, it was also operating in class C. It turns out that for some reason the gate2 on the failing MOSFET has broken down. DAMN!!!!!!!!
Digging in to the RF-deck
Failed MOSFET
Gate2 to source breakdown. 70 ohm dc-path between source and gate2 do not make any sense.
Some more SSPA development stuff.
Sorry for the low word count.
But then again, here are some videos 🙂
Have been working on my 144 MHz SSPA project since 04:00z this morning.
Now the time is 22:30z and I am tired. Continue tomorrow morning.
Here are some pictures of project status.
Starting point this moring
PT-100 Temperature sensor
Left/Front
Rear/Left
Rear/Left
Inside
More inside
73 All
ItaLab MD 2000 AR 144 BX module for 2m SSPA project.