QSX 10W HF Linear PA kit
It has been mentioned on this group a number of times in this discussion group so I am posting details here.
I have now made available the QRP Labs 10W HF Linear PA kit, providing 26dB of gain with +/-1dB gain flatness from 2-30MHz, 10W output all the way up to 10m band from 12V supply. This amplifier uses two BS170 in push-pull as the driver and two IRF510 in push-pull as the final stage. This kit shows that two IRF510 MOSFETs can produce excellent results in a high performance yet low cost ($26) linear amplifier kit.
See http://qrp-labs.com/linear for details.
I am not suggesting that this amplifier will solve all problems and without wishing to be offensive, the "garbage in, garbage out" rule always applies - in particular, if you feed it a signal containing spurs, harmonics, or other problems... then you will get the same thing at the other end, just amplified 26dB. It also still applies that all stages leading up to the final amplifier must have flat gain. If the pre-drivers cannot provide a big enough signal then you won't get full power output.
But, it could be useful or interesting, in the BITX context, to look at the details of this amplifier kit and see the short lead lengths, symmetric PCB and extensively "stitched" groundplanes.
I am very grateful to Allison KB1GMX for very valuable advice during the design and development of this amplifier, beta-testing prototypes, measurements and moral support.
73 Hans G0UPL