Besides the QRP-Labs 10w kit, which I see was discussed on another group as an option, (and qrpbuilder.com is using one on 6m, reportedly), there are options from 60dbm.com. Not the cheapest, but ready to go RD16HHF1 based 10, 20 and 50w boards, and even a cased version for 10w:
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Also, Mini-Kits down under has a 16w kit:
Their tests go up to 100 mhz...seems it'd be workable on 6m with the right cap value for C17.
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-Nate?
N8BTR