1. #ubitxv6-help
  2. V6.1 Blown output transistors and pcb trace

Re: V6.1 Blown output transistors and pcb trace #v6 #ubitxv6-help

Raj vu2zap
 

Stan,

Start with bias presets RV2 and RV3 at fully clockwise.. which is Zero in the uBitxs layout.

Key PTT and measure current consumed. Advance one preset to get 100mA more and the
second another 100mA more after first one.

Limit power supply to 1-2A, if current jumps then replace that preset.

Raj

At 16/11/2021, you wrote:
Thanks for that info, Raj. Very helpful! You’ve given me a great place to start and PA bias needs to be set regardless after replacing the IRF510s.

The primary reason I bought the uBitX was to have an open source platform with which to learn and experiment, so I’m going to read the ARRL Handbook sections on MOSFET characteristics and RF amplifier design before starting with the board.

A previous commenter, Evan AC9TU, mentioned a file of transistor measurements from a V4 board you posted and speculated that the RF readings should be the same on the V6 board. I’ll check that out also.

Stan K3PW
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