Another trip to the races.
The first SOT223 transistor I tried vindicated the switch to this package by being very robust. However, the gain was low and there was lots of distortion.
The second SOT223 transistor I tried was very robust with over 10dB of gain. I left it running at 10W for several minutes with no ill effects. And I pushed it to 20W without blowing anything. An encouraging development.
Now, if the gain was 10dB then the 1W driver amplifier board should not have a lot of distortion. However, it was distorted making me suspect the input to the 10W amplifier was not close to 50 ohms. While the results would only be ballpark and more of a pass/fail measurement I went to measure the input impedance to the 10W amplifier board with my nanoVNA.
Unfortunately the shed PC was dead with what appears to be a power supply fault. Most annoying. Now I know where the magic smoke I smelled a few days ago when i powered up the shed equipment came from.
It is a distraction but I think I will buy a refurbished desktop PC to replace the now defunct XP machine. It was my programming workhorse but I have learned over the last couple of years that I can get all my software running on Windows 10. So rather than persevere with it now seems a good time to switch.
I will progress this as time permits and given the milder autumn weather now I'm looking forward to tackling this soon.
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