No documentation was sent about any changes to the v2.
What happened was that the devices sent in April 2023 did not come with any information sheet, so on May 3rd, several messages came, which can be found on the sbitx.net page, how to set the performance and some similar information. The hardware modification was discussed on the forum and no information was released about the change.
So whoever modified it did it according to their own thoughts.
My own experience with the v2, which uses IRFZ24N FETs in the output stage:
1. I checked the electrical and mechanical connections of the device and repaired them as necessary. (FET clamper broke / D27 diode was faulty, so I replaced the power/swr diodes together / Bias adjustment was difficult, so I modified the circuit (see F5NPV website) / I replaced the mica insulator with Aluminum Nitride for better heat conduction / I cool the power stage heatsink with an external 92x92x25mm silent fan / I cool the RPi4 from the back with a 50x50x10mm fan fixed on an intermediate board / I use the PTT control of the power stage based on the designs of KX4Z Gordon Furthermore
2. I use the device with a current limit of 12.5V and 6.5 A, because it was not in use yet and I powered it from a battery, with a dummy load instead of an antenna, then one of the FETs of the power stage became shorted. The replaced and selected FETs have been working fine ever since!
Currently more than 8800 QSOs and these FETs have 168/150 dxcc/lotw since November 16, 2023.
3. I use a single antenna on 3 bands. This is a vertical delta loop antenna installed obliquely. There are two ferrite rings at the feed point (about 10 meters high).
One is for 100/50 Ohm and the other is for symmetrical/asymmetrical impedance matching.
I sized the 42.8 meter wire to 7 MHz, which can also be used at 14 and 21 MHz without an antenna tuner.
4. I consider myself a returning amateur radio operator because of sbitx, because I previously dismantled my antennas (2 el 5 band QQ, 20.8m high vertical) and I made this antenna only for sbitx, so that I could use it.
5. Most importantly, if it weren't for the amateurs who brought the development to the current level, I probably wouldn't be a device owner.
So a huge thank you to them for their continuous efforts to fix the bugs they find.
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That's all for my v2 story.
HA3HZ