Re: #u3s Relocating R5 #u3s


Well I’ve built a second u3s and used an RD-whatsit as a replacement for the BS170, and feeding it just 5V with a tiny bit of bias current (about 30mA measured on my Chinese budged volt and ammeter) giving about an 110mA total idle current, I’m measuring around 200mW RF output into the dummy load, across the 10M to 30M band and those in between.  

At around 180mA total idle current, it seems to go into self oscillation on certain frequencies with no measurable output but a lot of heat and around 450mA drain, which only ceases when the power feed is disconnected. 

Is this the same kind of problem you encountered in the 5W PA, if so I’ll try the same resistor mod that you recommended for that kit.

200 mW is fine, as I’ll use it to drive the 5W PA.

As I said, it’s only been connected to a dummy load so far, but I have used a radio and WSJT-X to validate the transmissions. 

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