Thank you for the reply Adam.
I don't have a CS-series transceiver working on 20M (or higher) yet. I'm still building.
Now I do already have a 10W amplifier for 40M, 30M, and 20M which I use with very low power CW rigs and thought it might be nice to be able use it with the CS-20 and a SLA battery (~12.5 vDC). The 10W amplifier is limited to 1W input power as built.
I think I'll just build myself a step attenuator box similar to this one:
---In CHINA_QRP@..., <rongxh@...> wrote :
It is not a good idea to reduce power by reducing IRF510's bias because it will make it work in poor situation.
How much power can you get so far? If you can get 5 watt or more, adding a power amplifier of 10 watt seems not very justified. If you really need higher power, you can consider raising the power supply voltage a little bit to somewhere at 14 volt.