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Those two diets you were talking about are not normal diodes they are transient voltage suppressors. They won’t conduct until the voltage gets around 10 V. Be very careful with that PA bias. You can

be certain that you have correctly identified the PA bias potentiometer. It would be very odd if turning that too far didn’t destroy the MOSFETs when you press push to talk the voltage on L 80 and

In my board I have additional diodes D8 and D9 connected between the gates of Q16 qnd Q17 and the ground. It seems that the voltage delivered by the bias circuit is limited by the those diodes to 270

JJ, I agree with Gordon's suggestions.? IRF520 would be a more robust part, and the TVS protection is a good idea as the driver circuit can deliver higher than the gate voltage if driven to full

I have one interesting finding. It seems that changing the PA_BIAS1 setting does not modify the current consumed by sBitx. After pressing PTT It increases from 0.31A to 0.77A, and does not depend on

one of the ports is for power, I don't think it provides data. [email protected]> wrote:

Unknown. I heated the end closer to the back of the PCB, and the cap fell right off the board, with a end still on the PCB. A check of the cap shows it is open, not surprising with the end

If C202 (47pf) SHORTED, you would expect potentially what is being seen. If the 80 meter filter were invoked, and your frequency is above that, the input of the filter might act like a short. If D15

Interesting why it cracked/failed... due to mechanical stress, like bent of PCB... temperature shock...? or was it already bad since new...

I hope so, you guys have been absolutely great! Stay tuned. 73, Richard AG5M On Friday, February 28, 2025 at 02:19:21 PM PST, tomekdm sp7etd via groups.io <tomekdm@...> wrote:

good to hear, radio will be fixed. 73

C30 removed. The end closest to the display came off when desoldering. PCB looks OK. With C30 removed, voltages on Q30 are: E = 1.74, B= 2.41, C=7.76 Pretty much as you mentioned. C30 will be

The RPi Zero 2 W has two USB 2.0 ports, I guess you could use an interposer board and include a USB-C connector, but it would only work at USB-2.0 speeds and increase the size of the radio.

The micro USB is the pi , in the future if they decide to use USBC, hopefully in the same footprint we will just need to make the hole a little bigger

JJ, that’s hard to say. I had huge Zener’s in mine, and I still lost a MOSFET with no obvious reason. I cannot guarantee it at that instant, but I had not seen any oscillations ever in my unit

I think some folks misunderstood what I was asking for. The sBitx V2 has IRFZ24N MOSFETs. We want to continue to use them for the finals. What mods have to be performed to prevent oscillations and

It's all good. Your information was useful for those who want to fully convert their V2 board to V3. Thank you. > > >

Good point Evan! But I can’t figure out is how disconnecting a Lowpass filter would result in a lower voltage. It should result in a higher voltage. I tried to look for what things might be

Sorry, my bad. It is 0.82 kOhm, not 0.82 as reported. Thanks for catching that. Base of Q30 is in fact 50.8 ohms. i rechecked. OK, C30 will get removed and voltages checked on Q30. 73, Richard

The USB ports are the actual USB ports on the Raspberry Pi Zero 2, so HFSignals didn't have much say in it. Joel N6ALT